@types/chai/index.d.ts

declare namespace Chai {
    type Message = string | (() => string);
    type ObjectProperty = string | symbol | number;

    interface PathInfo {
        parent: object;
        name: string;
        value?: any;
        exists: boolean;
    }

    interface ErrorConstructor {
        new(...args: any[]): Error;
    }

    interface ChaiUtils {
        addChainableMethod(
            // object to define the method on, e.g. chai.Assertion.prototype
            ctx: object,
            // method name
            name: string,
            // method itself; any arguments
            method: (...args: any[]) => void,
            // called when property is accessed
            chainingBehavior?: () => void,
        ): void;
        overwriteChainableMethod(
            ctx: object,
            name: string,
            method: (...args: any[]) => void,
            chainingBehavior?: () => void,
        ): void;
        addLengthGuard(
            fn: Function,
            assertionName: string,
            isChainable: boolean,
        ): void;
        addMethod(ctx: object, name: string, method: Function): void;
        addProperty(ctx: object, name: string, getter: () => any): void;
        overwriteMethod(ctx: object, name: string, method: Function): void;
        overwriteProperty(ctx: object, name: string, getter: (this: AssertionStatic, _super: any) => any): void;
        compareByInspect(a: object, b: object): -1 | 1;
        expectTypes(obj: object, types: string[]): void;
        flag(obj: object, key: string, value?: any): any;
        getActual(obj: object, args: AssertionArgs): any;
        getProperties(obj: object): string[];
        getEnumerableProperties(obj: object): string[];
        getOwnEnumerablePropertySymbols(obj: object): symbol[];
        getOwnEnumerableProperties(obj: object): Array<string | symbol>;
        getMessage(errorLike: Error | string): string;
        getMessage(obj: any, args: AssertionArgs): string;
        inspect(obj: any, showHidden?: boolean, depth?: number, colors?: boolean): string;
        isProxyEnabled(): boolean;
        objDisplay(obj: object): void;
        proxify(obj: object, nonChainableMethodName: string): object;
        test(obj: object, args: AssertionArgs): boolean;
        transferFlags(assertion: Assertion, obj: object, includeAll?: boolean): void;
        compatibleInstance(thrown: Error, errorLike: Error | ErrorConstructor): boolean;
        compatibleConstructor(thrown: Error, errorLike: Error | ErrorConstructor): boolean;
        compatibleMessage(thrown: Error, errMatcher: string | RegExp): boolean;
        getConstructorName(constructorFn: Function): string;
        getFuncName(constructorFn: Function): string | null;

        // Reexports from pathval:
        hasProperty(obj: object | undefined | null, name: ObjectProperty): boolean;
        getPathInfo(obj: object, path: string): PathInfo;
        getPathValue(obj: object, path: string): object | undefined;
    }

    type ChaiPlugin = (chai: ChaiStatic, utils: ChaiUtils) => void;

    interface ChaiStatic {
        expect: ExpectStatic;
        should(): Should;
        /**
         * Provides a way to extend the internals of Chai
         */
        use(fn: ChaiPlugin): ChaiStatic;
        util: ChaiUtils;
        assert: AssertStatic;
        config: Config;
        Assertion: AssertionStatic;
        AssertionError: typeof AssertionError;
        version: string;
    }

    export interface ExpectStatic {
        (val: any, message?: string): Assertion;
        fail(message?: string): never;
        fail(actual: any, expected: any, message?: string, operator?: Operator): never;
    }

    export interface AssertStatic extends Assert {
    }

    // chai.Assertion.prototype.assert arguments
    type AssertionArgs = [
        // 'expression to be tested'
        // This parameter is unused and the docs list its type as
        // 'Philosophical', which is mentioned nowhere else in the source. Do
        // with that what you will!
        any,
        Message, // message if value fails
        Message, // message if negated value fails
        any, // expected value
        any?, // actual value
        boolean?, // showDiff
    ];

    export interface AssertionPrototype {
        assert(...args: AssertionArgs): void;
        _obj: any;
    }

    export interface AssertionStatic extends AssertionPrototype {
        prototype: AssertionPrototype;

        new(target: any, message?: string, ssfi?: Function, lockSsfi?: boolean): Assertion;

        // Deprecated properties:
        includeStack: boolean;
        showDiff: boolean;

        // Partials of functions on ChaiUtils:
        addProperty(name: string, getter: (this: AssertionStatic) => any): void;
        addMethod(name: string, method: (this: AssertionStatic, ...args: any[]) => any): void;
        addChainableMethod(
            name: string,
            method: (this: AssertionStatic, ...args: any[]) => void,
            chainingBehavior?: () => void,
        ): void;
        overwriteProperty(name: string, getter: (this: AssertionStatic, _super: any) => any): void;
        overwriteMethod(name: string, method: (this: AssertionStatic, ...args: any[]) => any): void;
        overwriteChainableMethod(
            name: string,
            method: (this: AssertionStatic, ...args: any[]) => void,
            chainingBehavior?: () => void,
        ): void;
    }

    export type Operator = string; // "==" | "===" | ">" | ">=" | "<" | "<=" | "!=" | "!==";

    export type OperatorComparable = boolean | null | number | string | undefined | Date;

    interface ShouldAssertion {
        equal(value1: any, value2: any, message?: string): void;
        Throw: ShouldThrow;
        throw: ShouldThrow;
        exist(value: any, message?: string): void;
    }

    interface Should extends ShouldAssertion {
        not: ShouldAssertion;
        fail(message?: string): never;
        fail(actual: any, expected: any, message?: string, operator?: Operator): never;
    }

    interface ShouldThrow {
        (actual: Function, expected?: string | RegExp, message?: string): void;
        (actual: Function, constructor: Error | Function, expected?: string | RegExp, message?: string): void;
    }

    interface Assertion extends LanguageChains, NumericComparison, TypeComparison {
        not: Assertion;
        deep: Deep;
        ordered: Ordered;
        nested: Nested;
        own: Own;
        any: KeyFilter;
        all: KeyFilter;
        a: Assertion;
        an: Assertion;
        include: Include;
        includes: Include;
        contain: Include;
        contains: Include;
        ok: Assertion;
        true: Assertion;
        false: Assertion;
        null: Assertion;
        undefined: Assertion;
        NaN: Assertion;
        exist: Assertion;
        empty: Assertion;
        arguments: Assertion;
        Arguments: Assertion;
        finite: Assertion;
        equal: Equal;
        equals: Equal;
        eq: Equal;
        eql: Equal;
        eqls: Equal;
        property: Property;
        ownProperty: Property;
        haveOwnProperty: Property;
        ownPropertyDescriptor: OwnPropertyDescriptor;
        haveOwnPropertyDescriptor: OwnPropertyDescriptor;
        length: Length;
        lengthOf: Length;
        match: Match;
        matches: Match;
        string(string: string, message?: string): Assertion;
        keys: Keys;
        key(string: string): Assertion;
        throw: Throw;
        throws: Throw;
        Throw: Throw;
        respondTo: RespondTo;
        respondsTo: RespondTo;
        itself: Assertion;
        satisfy: Satisfy;
        satisfies: Satisfy;
        closeTo: CloseTo;
        approximately: CloseTo;
        members: Members;
        increase: PropertyChange;
        increases: PropertyChange;
        decrease: PropertyChange;
        decreases: PropertyChange;
        change: PropertyChange;
        changes: PropertyChange;
        extensible: Assertion;
        sealed: Assertion;
        frozen: Assertion;
        oneOf: OneOf;
    }

    interface LanguageChains {
        to: Assertion;
        be: Assertion;
        been: Assertion;
        is: Assertion;
        that: Assertion;
        which: Assertion;
        and: Assertion;
        has: Assertion;
        have: Assertion;
        with: Assertion;
        at: Assertion;
        of: Assertion;
        same: Assertion;
        but: Assertion;
        does: Assertion;
    }

    interface NumericComparison {
        above: NumberComparer;
        gt: NumberComparer;
        greaterThan: NumberComparer;
        least: NumberComparer;
        gte: NumberComparer;
        greaterThanOrEqual: NumberComparer;
        below: NumberComparer;
        lt: NumberComparer;
        lessThan: NumberComparer;
        most: NumberComparer;
        lte: NumberComparer;
        lessThanOrEqual: NumberComparer;
        within(start: number, finish: number, message?: string): Assertion;
        within(start: Date, finish: Date, message?: string): Assertion;
    }

    interface NumberComparer {
        (value: number | Date, message?: string): Assertion;
    }

    interface TypeComparison {
        (type: string, message?: string): Assertion;
        instanceof: InstanceOf;
        instanceOf: InstanceOf;
    }

    interface InstanceOf {
        (constructor: any, message?: string): Assertion;
    }

    interface CloseTo {
        (expected: number, delta: number, message?: string): Assertion;
    }

    interface Nested {
        include: Include;
        includes: Include;
        contain: Include;
        contains: Include;
        property: Property;
        members: Members;
    }

    interface Own {
        include: Include;
        includes: Include;
        contain: Include;
        contains: Include;
        property: Property;
    }

    interface Deep extends KeyFilter {
        be: Assertion;
        equal: Equal;
        equals: Equal;
        eq: Equal;
        include: Include;
        includes: Include;
        contain: Include;
        contains: Include;
        property: Property;
        ordered: Ordered;
        nested: Nested;
        oneOf: OneOf;
        own: Own;
    }

    interface Ordered {
        members: Members;
    }

    interface KeyFilter {
        keys: Keys;
        members: Members;
    }

    interface Equal {
        (value: any, message?: string): Assertion;
    }

    interface Property {
        (name: string | symbol, value: any, message?: string): Assertion;
        (name: string | symbol, message?: string): Assertion;
    }

    interface OwnPropertyDescriptor {
        (name: string | symbol, descriptor: PropertyDescriptor, message?: string): Assertion;
        (name: string | symbol, message?: string): Assertion;
    }

    interface Length extends LanguageChains, NumericComparison {
        (length: number, message?: string): Assertion;
    }

    interface Include {
        (value: any, message?: string): Assertion;
        keys: Keys;
        deep: Deep;
        ordered: Ordered;
        members: Members;
        any: KeyFilter;
        all: KeyFilter;
        oneOf: OneOf;
    }

    interface OneOf {
        (list: readonly unknown[], message?: string): Assertion;
    }

    interface Match {
        (regexp: RegExp, message?: string): Assertion;
    }

    interface Keys {
        (...keys: string[]): Assertion;
        (keys: readonly any[] | Object): Assertion;
    }

    interface Throw {
        (expected?: string | RegExp, message?: string): Assertion;
        (constructor: Error | Function, expected?: string | RegExp, message?: string): Assertion;
    }

    interface RespondTo {
        (method: string, message?: string): Assertion;
    }

    interface Satisfy {
        (matcher: Function, message?: string): Assertion;
    }

    interface Members {
        (set: readonly any[], message?: string): Assertion;
    }

    interface PropertyChange {
        (object: Object, property?: string, message?: string): DeltaAssertion;
    }

    interface DeltaAssertion extends Assertion {
        by(delta: number, msg?: string): Assertion;
    }

    export interface Assert {
        /**
         * @param expression    Expression to test for truthiness.
         * @param message    Message to display on error.
         */
        (expression: any, message?: string): asserts expression;

        /**
         * Throws a failure.
         *
         * @param message    Message to display on error.
         * @remarks Node.js assert module-compatible.
         */
        fail(message?: string): never;

        /**
         * Throws a failure.
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message    Message to display on error.
         * @param operator   Comparison operator, if not strict equality.
         * @remarks Node.js assert module-compatible.
         */
        fail<T>(actual: T, expected: T, message?: string, operator?: Operator): never;

        /**
         * Asserts that object is truthy.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param message    Message to display on error.
         */
        isOk<T>(value: T, message?: string): void;

        /**
         * Asserts that object is truthy.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param message    Message to display on error.
         */
        ok<T>(value: T, message?: string): void;

        /**
         * Asserts that object is falsy.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param message    Message to display on error.
         */
        isNotOk<T>(value: T, message?: string): void;

        /**
         * Asserts that object is falsy.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param message    Message to display on error.
         */
        notOk<T>(value: T, message?: string): void;

        /**
         * Asserts non-strict equality (==) of actual and expected.
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message   Message to display on error.
         */
        equal<T>(actual: T, expected: T, message?: string): void;

        /**
         * Asserts non-strict inequality (!=) of actual and expected.
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message   Message to display on error.
         */
        notEqual<T>(actual: T, expected: T, message?: string): void;

        /**
         * Asserts strict equality (===) of actual and expected.
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message   Message to display on error.
         */
        strictEqual<T>(actual: T, expected: T, message?: string): void;

        /**
         * Asserts strict inequality (!==) of actual and expected.
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message   Message to display on error.
         */
        notStrictEqual<T>(actual: T, expected: T, message?: string): void;

        /**
         * Asserts that actual is deeply equal to expected.
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message   Message to display on error.
         */
        deepEqual<T>(actual: T, expected: T, message?: string): void;

        /**
         * Asserts that actual is not deeply equal to expected.
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message   Message to display on error.
         */
        notDeepEqual<T>(actual: T, expected: T, message?: string): void;

        /**
         * Alias to deepEqual
         *
         * T   Type of the objects.
         * @param actual   Actual value.
         * @param expected   Potential expected value.
         * @param message   Message to display on error.
         */
        deepStrictEqual<T>(actual: T, expected: T, message?: string): void;

        /**
         * Asserts valueToCheck is strictly greater than (>) valueToBeAbove.
         *
         * @param valueToCheck   Actual value.
         * @param valueToBeAbove   Minimum Potential expected value.
         * @param message   Message to display on error.
         */
        isAbove(valueToCheck: number, valueToBeAbove: number, message?: string): void;

        /**
         * Asserts valueToCheck is greater than or equal to (>=) valueToBeAtLeast.
         *
         * @param valueToCheck   Actual value.
         * @param valueToBeAtLeast   Minimum Potential expected value.
         * @param message   Message to display on error.
         */
        isAtLeast(valueToCheck: number, valueToBeAtLeast: number, message?: string): void;

        /**
         * Asserts valueToCheck is strictly less than (<) valueToBeBelow.
         *
         * @param valueToCheck   Actual value.
         * @param valueToBeBelow   Minimum Potential expected value.
         * @param message   Message to display on error.
         */
        isBelow(valueToCheck: number, valueToBeBelow: number, message?: string): void;

        /**
         * Asserts valueToCheck is less than or equal to (<=) valueToBeAtMost.
         *
         * @param valueToCheck   Actual value.
         * @param valueToBeAtMost   Minimum Potential expected value.
         * @param message   Message to display on error.
         */
        isAtMost(valueToCheck: number, valueToBeAtMost: number, message?: string): void;

        /**
         * Asserts that value is true.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isTrue<T>(value: T, message?: string): void;

        /**
         * Asserts that value is false.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isFalse<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not true.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotTrue<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not false.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotFalse<T>(value: T, message?: string): void;

        /**
         * Asserts that value is null.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNull<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not null.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotNull<T>(value: T, message?: string): void;

        /**
         * Asserts that value is NaN.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNaN<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not NaN.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotNaN<T>(value: T, message?: string): void;

        /**
         * Asserts that the target is neither null nor undefined.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message    Message to display on error.
         */
        exists<T>(value: T, message?: string): void;

        /**
         * Asserts that the target is either null or undefined.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message    Message to display on error.
         */
        notExists<T>(value: T, message?: string): void;

        /**
         * Asserts that value is undefined.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isUndefined<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not undefined.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isDefined<T>(value: T, message?: string): void;

        /**
         * Asserts that value is a function.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isFunction<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not a function.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotFunction<T>(value: T, message?: string): void;

        /**
         * Asserts that value is an object of type 'Object'
         * (as revealed by Object.prototype.toString).
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         * @remarks The assertion does not match subclassed objects.
         */
        isObject<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not an object of type 'Object'
         * (as revealed by Object.prototype.toString).
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotObject<T>(value: T, message?: string): void;

        /**
         * Asserts that value is an array.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isArray<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not an array.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotArray<T>(value: T, message?: string): void;

        /**
         * Asserts that value is a string.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isString<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not a string.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotString<T>(value: T, message?: string): void;

        /**
         * Asserts that value is a number.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNumber<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not a number.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotNumber<T>(value: T, message?: string): void;

        /**
         * Asserts that value is a finite number.
         * Unlike `.isNumber`, this will fail for `NaN` and `Infinity`.
         *
         * T   Type of value
         * @param value    Actual value
         * @param message   Message to display on error.
         */
        isFinite<T>(value: T, message?: string): void;

        /**
         * Asserts that value is a boolean.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isBoolean<T>(value: T, message?: string): void;

        /**
         * Asserts that value is not a boolean.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param message   Message to display on error.
         */
        isNotBoolean<T>(value: T, message?: string): void;

        /**
         * Asserts that value's type is name, as determined by Object.prototype.toString.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param name   Potential expected type name of value.
         * @param message   Message to display on error.
         */
        typeOf<T>(value: T, name: string, message?: string): void;

        /**
         * Asserts that value's type is not name, as determined by Object.prototype.toString.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param name   Potential expected type name of value.
         * @param message   Message to display on error.
         */
        notTypeOf<T>(value: T, name: string, message?: string): void;

        /**
         * Asserts that value is an instance of constructor.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param constructor   Potential expected contructor of value.
         * @param message   Message to display on error.
         */
        instanceOf<T>(value: T, constructor: Function, message?: string): void;

        /**
         * Asserts that value is not an instance of constructor.
         *
         * T   Type of value.
         * @param value   Actual value.
         * @param constructor   Potential expected contructor of value.
         * @param message   Message to display on error.
         */
        notInstanceOf<T>(value: T, type: Function, message?: string): void;

        /**
         * Asserts that haystack includes needle.
         *
         * @param haystack   Container string.
         * @param needle   Potential substring of haystack.
         * @param message   Message to display on error.
         */
        include(haystack: string, needle: string, message?: string): void;

        /**
         * Asserts that haystack includes needle.
         *
         * T   Type of values in haystack.
         * @param haystack   Container array, set or map.
         * @param needle   Potential value contained in haystack.
         * @param message   Message to display on error.
         */
        include<T>(
            haystack: readonly T[] | ReadonlySet<T> | ReadonlyMap<any, T>,
            needle: T,
            message?: string,
        ): void;

        /**
         * Asserts that haystack includes needle.
         *
         * T   Type of values in haystack.
         * @param haystack   WeakSet container.
         * @param needle   Potential value contained in haystack.
         * @param message   Message to display on error.
         */
        include<T extends object>(haystack: WeakSet<T>, needle: T, message?: string): void;

        /**
         * Asserts that haystack includes needle.
         *
         * T   Type of haystack.
         * @param haystack   Object.
         * @param needle   Potential subset of the haystack's properties.
         * @param message   Message to display on error.
         */
        include<T>(haystack: T, needle: Partial<T>, message?: string): void;

        /**
         * Asserts that haystack does not includes needle.
         *
         * @param haystack   Container string.
         * @param needle   Potential substring of haystack.
         * @param message   Message to display on error.
         */
        notInclude(haystack: string, needle: string, message?: string): void;

        /**
         * Asserts that haystack does not includes needle.
         *
         * T   Type of values in haystack.
         * @param haystack   Container array, set or map.
         * @param needle   Potential value contained in haystack.
         * @param message   Message to display on error.
         */
        notInclude<T>(
            haystack: readonly T[] | ReadonlySet<T> | ReadonlyMap<any, T>,
            needle: T,
            message?: string,
        ): void;

        /**
         * Asserts that haystack does not includes needle.
         *
         * T   Type of values in haystack.
         * @param haystack   WeakSet container.
         * @param needle   Potential value contained in haystack.
         * @param message   Message to display on error.
         */
        notInclude<T extends object>(haystack: WeakSet<T>, needle: T, message?: string): void;

        /**
         * Asserts that haystack does not includes needle.
         *
         * T   Type of haystack.
         * @param haystack   Object.
         * @param needle   Potential subset of the haystack's properties.
         * @param message   Message to display on error.
         */
        notInclude<T>(haystack: T, needle: Partial<T>, message?: string): void;

        /**
         * Asserts that haystack includes needle. Deep equality is used.
         *
         * @param haystack   Container string.
         * @param needle   Potential substring of haystack.
         * @param message   Message to display on error.
         *
         * @deprecated Does not have any effect on string. Use {@link Assert#include} instead.
         */
        deepInclude(haystack: string, needle: string, message?: string): void;

        /**
         * Asserts that haystack includes needle. Deep equality is used.
         *
         * T   Type of values in haystack.
         * @param haystack   Container array, set or map.
         * @param needle   Potential value contained in haystack.
         * @param message   Message to display on error.
         */
        deepInclude<T>(
            haystack: readonly T[] | ReadonlySet<T> | ReadonlyMap<any, T>,
            needle: T,
            message?: string,
        ): void;

        /**
         * Asserts that haystack does not includes needle.
         *
         * T   Type of haystack.
         * @param haystack   Object.
         * @param needle   Potential subset of the haystack's properties.
         * @param message   Message to display on error.
         */
        deepInclude<T>(haystack: T, needle: T extends WeakSet<any> ? never : Partial<T>, message?: string): void;

        /**
         * Asserts that haystack does not includes needle. Deep equality is used.
         *
         * @param haystack   Container string.
         * @param needle   Potential substring of haystack.
         * @param message   Message to display on error.
         *
         * @deprecated Does not have any effect on string. Use {@link Assert#notInclude} instead.
         */
        notDeepInclude(haystack: string, needle: string, message?: string): void;

        /**
         * Asserts that haystack does not includes needle. Deep equality is used.
         *
         * T   Type of values in haystack.
         * @param haystack   Container array, set or map.
         * @param needle   Potential value contained in haystack.
         * @param message   Message to display on error.
         */
        notDeepInclude<T>(
            haystack: readonly T[] | ReadonlySet<T> | ReadonlyMap<any, T>,
            needle: T,
            message?: string,
        ): void;

        /**
         * Asserts that haystack does not includes needle. Deep equality is used.
         *
         * T   Type of haystack.
         * @param haystack   Object.
         * @param needle   Potential subset of the haystack's properties.
         * @param message   Message to display on error.
         */
        notDeepInclude<T>(haystack: T, needle: T extends WeakSet<any> ? never : Partial<T>, message?: string): void;

        /**
         * Asserts that ‘haystack’ includes ‘needle’. Can be used to assert the inclusion of a subset of properties in an object.
         *
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.Asserts that ‘haystack’ includes ‘needle’.
         * Can be used to assert the inclusion of a subset of properties in an object.
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        nestedInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that ‘haystack’ does not include ‘needle’. Can be used to assert the absence of a subset of properties in an object.
         *
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.Asserts that ‘haystack’ includes ‘needle’.
         * Can be used to assert the inclusion of a subset of properties in an object.
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        notNestedInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that ‘haystack’ includes ‘needle’. Can be used to assert the inclusion of a subset of properties in an object while checking for deep equality
         *
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.Asserts that ‘haystack’ includes ‘needle’.
         * Can be used to assert the inclusion of a subset of properties in an object.
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        deepNestedInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that ‘haystack’ does not include ‘needle’. Can be used to assert the absence of a subset of properties in an object while checking for deep equality.
         *
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.Asserts that ‘haystack’ includes ‘needle’.
         * Can be used to assert the inclusion of a subset of properties in an object.
         * Enables the use of dot- and bracket-notation for referencing nested properties.
         * ‘[]’ and ‘.’ in property names can be escaped using double backslashes.
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        notDeepNestedInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that ‘haystack’ includes ‘needle’. Can be used to assert the inclusion of a subset of properties in an object while ignoring inherited properties.
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        ownInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that ‘haystack’ includes ‘needle’. Can be used to assert the absence of a subset of properties in an object while ignoring inherited properties.
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        notOwnInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that ‘haystack’ includes ‘needle’. Can be used to assert the inclusion of a subset of properties in an object while ignoring inherited properties and checking for deep
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        deepOwnInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that ‘haystack’ includes ‘needle’. Can be used to assert the absence of a subset of properties in an object while ignoring inherited properties and checking for deep equality.
         *
         * @param haystack
         * @param needle
         * @param message   Message to display on error.
         */
        notDeepOwnInclude(haystack: any, needle: any, message?: string): void;

        /**
         * Asserts that value matches the regular expression regexp.
         *
         * @param value   Actual value.
         * @param regexp   Potential match of value.
         * @param message   Message to display on error.
         */
        match(value: string, regexp: RegExp, message?: string): void;

        /**
         * Asserts that value does not match the regular expression regexp.
         *
         * @param value   Actual value.
         * @param regexp   Potential match of value.
         * @param message   Message to display on error.
         */
        notMatch(expected: any, regexp: RegExp, message?: string): void;

        /**
         * Asserts that object has a property named by property.
         *
         * T   Type of object.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param message   Message to display on error.
         */
        property<T>(object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that object has a property named by property.
         *
         * T   Type of object.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param message   Message to display on error.
         */
        notProperty<T>(object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that object has a property named by property, which can be a string
         * using dot- and bracket-notation for deep reference.
         *
         * T   Type of object.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param message   Message to display on error.
         */
        deepProperty<T>(object: T, property: string, message?: string): void;

        /**
         * Asserts that object does not have a property named by property, which can be a
         * string using dot- and bracket-notation for deep reference.
         *
         * T   Type of object.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param message   Message to display on error.
         */
        notDeepProperty<T>(object: T, property: string, message?: string): void;

        /**
         * Asserts that object has a property named by property with value given by value.
         *
         * T   Type of object.
         * V   Type of value.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param value   Potential expected property value.
         * @param message   Message to display on error.
         */
        propertyVal<T, V>(object: T, property: string, /* keyof T */ value: V, message?: string): void;

        /**
         * Asserts that object has a property named by property with value given by value.
         *
         * T   Type of object.
         * V   Type of value.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param value   Potential expected property value.
         * @param message   Message to display on error.
         */
        notPropertyVal<T, V>(object: T, property: string, /* keyof T */ value: V, message?: string): void;

        /**
         * Asserts that object has a property named by property, which can be a string
         * using dot- and bracket-notation for deep reference.
         *
         * T   Type of object.
         * V   Type of value.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param value   Potential expected property value.
         * @param message   Message to display on error.
         */
        deepPropertyVal<T, V>(object: T, property: string, value: V, message?: string): void;

        /**
         * Asserts that object does not have a property named by property, which can be a
         * string using dot- and bracket-notation for deep reference.
         *
         * T   Type of object.
         * V   Type of value.
         * @param object   Container object.
         * @param property   Potential contained property of object.
         * @param value   Potential expected property value.
         * @param message   Message to display on error.
         */
        notDeepPropertyVal<T, V>(object: T, property: string, value: V, message?: string): void;

        /**
         * Asserts that object has a length property with the expected value.
         *
         * T   Type of object.
         * @param object   Container object.
         * @param length   Potential expected length of object.
         * @param message   Message to display on error.
         */
        lengthOf<T extends { readonly length?: number | undefined } | { readonly size?: number | undefined }>(
            object: T,
            length: number,
            message?: string,
        ): void;

        /**
         * Asserts that fn will throw an error.
         *
         * @param fn   Function that may throw.
         * @param errMsgMatcher   Expected error message matcher.
         * @param ignored   Ignored parameter.
         * @param message   Message to display on error.
         */
        throw(fn: () => void, errMsgMatcher?: RegExp | string, ignored?: any, message?: string): void;

        /**
         * Asserts that fn will throw an error.
         *
         * @param fn   Function that may throw.
         * @param errorLike   Expected error constructor or error instance.
         * @param errMsgMatcher   Expected error message matcher.
         * @param message   Message to display on error.
         */
        throw(
            fn: () => void,
            errorLike?: ErrorConstructor | Error | null,
            errMsgMatcher?: RegExp | string | null,
            message?: string,
        ): void;

        /**
         * Asserts that fn will throw an error.
         *
         * @param fn   Function that may throw.
         * @param errMsgMatcher   Expected error message matcher.
         * @param ignored   Ignored parameter.
         * @param message   Message to display on error.
         */
        throws(fn: () => void, errMsgMatcher?: RegExp | string, ignored?: any, message?: string): void;

        /**
         * Asserts that fn will throw an error.
         *
         * @param fn   Function that may throw.
         * @param errorLike   Expected error constructor or error instance.
         * @param errMsgMatcher   Expected error message matcher.
         * @param message   Message to display on error.
         */
        throws(
            fn: () => void,
            errorLike?: ErrorConstructor | Error | null,
            errMsgMatcher?: RegExp | string | null,
            message?: string,
        ): void;

        /**
         * Asserts that fn will throw an error.
         *
         * @param fn   Function that may throw.
         * @param errMsgMatcher   Expected error message matcher.
         * @param ignored   Ignored parameter.
         * @param message   Message to display on error.
         */
        Throw(fn: () => void, errMsgMatcher?: RegExp | string, ignored?: any, message?: string): void;

        /**
         * Asserts that fn will throw an error.
         *
         * @param fn   Function that may throw.
         * @param errorLike   Expected error constructor or error instance.
         * @param errMsgMatcher   Expected error message matcher.
         * @param message   Message to display on error.
         */
        Throw(
            fn: () => void,
            errorLike?: ErrorConstructor | Error | null,
            errMsgMatcher?: RegExp | string | null,
            message?: string,
        ): void;

        /**
         * Asserts that fn will not throw an error.
         *
         * @param fn   Function that may throw.
         * @param errMsgMatcher   Expected error message matcher.
         * @param ignored   Ignored parameter.
         * @param message   Message to display on error.
         */
        doesNotThrow(fn: () => void, errMsgMatcher?: RegExp | string, ignored?: any, message?: string): void;

        /**
         * Asserts that fn will not throw an error.
         *
         * @param fn   Function that may throw.
         * @param errorLike   Expected error constructor or error instance.
         * @param errMsgMatcher   Expected error message matcher.
         * @param message   Message to display on error.
         */
        doesNotThrow(
            fn: () => void,
            errorLike?: ErrorConstructor | Error | null,
            errMsgMatcher?: RegExp | string | null,
            message?: string,
        ): void;

        /**
         * Compares two values using operator.
         *
         * @param val1   Left value during comparison.
         * @param operator   Comparison operator.
         * @param val2   Right value during comparison.
         * @param message   Message to display on error.
         */
        operator(val1: OperatorComparable, operator: Operator, val2: OperatorComparable, message?: string): void;

        /**
         * Asserts that the target is equal to expected, to within a +/- delta range.
         *
         * @param actual   Actual value
         * @param expected   Potential expected value.
         * @param delta   Maximum differenced between values.
         * @param message   Message to display on error.
         */
        closeTo(actual: number, expected: number, delta: number, message?: string): void;

        /**
         * Asserts that the target is equal to expected, to within a +/- delta range.
         *
         * @param actual   Actual value
         * @param expected   Potential expected value.
         * @param delta   Maximum differenced between values.
         * @param message   Message to display on error.
         */
        approximately(act: number, exp: number, delta: number, message?: string): void;

        /**
         * Asserts that set1 and set2 have the same members. Order is not take into account.
         *
         * T   Type of set values.
         * @param set1   Actual set of values.
         * @param set2   Potential expected set of values.
         * @param message   Message to display on error.
         */
        sameMembers<T>(set1: T[], set2: T[], message?: string): void;

        /**
         * Asserts that set1 and set2 have the same members using deep equality checking.
         * Order is not take into account.
         *
         * T   Type of set values.
         * @param set1   Actual set of values.
         * @param set2   Potential expected set of values.
         * @param message   Message to display on error.
         */
        sameDeepMembers<T>(set1: T[], set2: T[], message?: string): void;

        /**
         * Asserts that `set1` and `set2` don't have the same members in any order.
         * Uses a deep equality check.
         *
         *  T   Type of set values.
         * @param set1
         * @param set2
         * @param message
         */
        notSameDeepMembers<T>(set1: T[], set2: T[], message?: string): void;

        /**
         * Asserts that set1 and set2 have the same members in the same order.
         * Uses a strict equality check (===).
         *
         * T   Type of set values.
         * @param set1   Actual set of values.
         * @param set2   Potential expected set of values.
         * @param message   Message to display on error.
         */
        sameOrderedMembers<T>(set1: T[], set2: T[], message?: string): void;

        /**
         * Asserts that set1 and set2 don’t have the same members in the same order.
         * Uses a strict equality check (===).
         *
         * T   Type of set values.
         * @param set1   Actual set of values.
         * @param set2   Potential expected set of values.
         * @param message   Message to display on error.
         */
        notSameOrderedMembers<T>(set1: T[], set2: T[], message?: string): void;

        /**
         * Asserts that set1 and set2 have the same members in the same order.
         * Uses a deep equality check.
         *
         * T   Type of set values.
         * @param set1   Actual set of values.
         * @param set2   Potential expected set of values.
         * @param message   Message to display on error.
         */
        sameDeepOrderedMembers<T>(set1: T[], set2: T[], message?: string): void;

        /**
         * Asserts that set1 and set2 don’t have the same members in the same order.
         * Uses a deep equality check.
         *
         * T   Type of set values.
         * @param set1   Actual set of values.
         * @param set2   Potential expected set of values.
         * @param message   Message to display on error.
         */
        notSameDeepOrderedMembers<T>(set1: T[], set2: T[], message?: string): void;

        /**
         * Asserts that subset is included in superset in the same order beginning with the first element in superset.
         * Uses a strict equality check (===).
         *
         * T   Type of set values.
         * @param superset   Actual set of values.
         * @param subset   Potential contained set of values.
         * @param message   Message to display on error.
         */
        includeOrderedMembers<T>(superset: T[], subset: T[], message?: string): void;

        /**
         * Asserts that subset isn’t included in superset in the same order beginning with the first element in superset.
         * Uses a strict equality check (===).
         *
         * T   Type of set values.
         * @param superset   Actual set of values.
         * @param subset   Potential contained set of values.
         * @param message   Message to display on error.
         */
        notIncludeOrderedMembers<T>(superset: T[], subset: T[], message?: string): void;

        /**
         * Asserts that subset is included in superset in the same order beginning with the first element in superset.
         * Uses a deep equality check.
         *
         * T   Type of set values.
         * @param superset   Actual set of values.
         * @param subset   Potential contained set of values.
         * @param message   Message to display on error.
         */
        includeDeepOrderedMembers<T>(superset: T[], subset: T[], message?: string): void;

        /**
         * Asserts that subset isn’t included in superset in the same order beginning with the first element in superset.
         * Uses a deep equality check.
         *
         * T   Type of set values.
         * @param superset   Actual set of values.
         * @param subset   Potential contained set of values.
         * @param message   Message to display on error.
         */
        notIncludeDeepOrderedMembers<T>(superset: T[], subset: T[], message?: string): void;

        /**
         * Asserts that subset is included in superset. Order is not take into account.
         *
         * T   Type of set values.
         * @param superset   Actual set of values.
         * @param subset   Potential contained set of values.
         * @param message   Message to display on error.
         */
        includeMembers<T>(superset: T[], subset: T[], message?: string): void;

        /**
         * Asserts that subset isn’t included in superset in any order.
         * Uses a strict equality check (===). Duplicates are ignored.
         *
         * T   Type of set values.
         * @param superset   Actual set of values.
         * @param subset   Potential not contained set of values.
         * @param message   Message to display on error.
         */
        notIncludeMembers<T>(superset: T[], subset: T[], message?: string): void;

        /**
         * Asserts that subset is included in superset using deep equality checking.
         * Order is not take into account.
         *
         * T   Type of set values.
         * @param superset   Actual set of values.
         * @param subset   Potential contained set of values.
         * @param message   Message to display on error.
         */
        includeDeepMembers<T>(superset: T[], subset: T[], message?: string): void;

        /**
         * Asserts that non-object, non-array value inList appears in the flat array list.
         *
         * T   Type of list values.
         * @param inList   Value expected to be in the list.
         * @param list   List of values.
         * @param message   Message to display on error.
         */
        oneOf<T>(inList: T, list: T[], message?: string): void;

        /**
         * Asserts that a function changes the value of a property.
         *
         * T   Type of object.
         * @param modifier   Function to run.
         * @param object   Container object.
         * @param property   Property of object expected to be modified.
         * @param message   Message to display on error.
         */
        changes<T>(modifier: Function, object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that a function changes the value of a property by an amount (delta).
         *
         * @param modifier function
         * @param object or getter function
         * @param property name _optional_
         * @param change amount (delta)
         * @param message _optional_
         */
        changesBy<T>(
            modifier: Function,
            object: T,
            property: string,
            /* keyof T */ change: number,
            message?: string,
        ): void;
        changesBy<T>(modifier: Function, object: T, change: number, message?: string): void;

        /**
         * Asserts that a function does not change the value of a property.
         *
         * T   Type of object.
         * @param modifier   Function to run.
         * @param object   Container object.
         * @param property   Property of object expected not to be modified.
         * @param message   Message to display on error.
         */
        doesNotChange<T>(modifier: Function, object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that a function increases an object property.
         *
         * T   Type of object.
         * @param modifier   Function to run.
         * @param object   Container object.
         * @param property   Property of object expected to be increased.
         * @param message   Message to display on error.
         */
        increases<T>(modifier: Function, object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that a function increases a numeric object property or a function's return value by an amount (delta).
         *
         * T   Type of object or function.
         * @param modifier function
         * @param object or getter function
         * @param property name _optional_
         * @param change amount (delta)
         * @param message _optional_
         */
        increasesBy<T>(
            modifier: Function,
            object: T,
            property: string,
            /* keyof T */ change: number,
            message?: string,
        ): void;
        increasesBy<T>(modifier: Function, object: T, change: number, message?: string): void;

        /**
         * Asserts that a function does not increase an object property.
         *
         * T   Type of object.
         * @param modifier   Function to run.
         * @param object   Container object.
         * @param property   Property of object expected not to be increased.
         * @param message   Message to display on error.
         */
        doesNotIncrease<T>(modifier: Function, object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that a function does not increase a numeric object property or function's return value by an amount (delta).
         *
         * T   Type of object or function.
         * @param modifier function
         * @param object or getter function
         * @param property name _optional_
         * @param change amount (delta)
         * @param message _optional_
         */

        increasesButNotBy<T>(
            modifier: Function,
            object: T,
            property: string,
            /* keyof T */ change: number,
            message?: string,
        ): void;
        increasesButNotBy<T>(modifier: Function, object: T, change: number, message?: string): void;

        /**
         * Asserts that a function decreases an object property.
         *
         * T   Type of object.
         * @param modifier   Function to run.
         * @param object   Container object.
         * @param property   Property of object expected to be decreased.
         * @param message   Message to display on error.
         */
        decreases<T>(modifier: Function, object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that a function decreases a numeric object property or a function's return value by an amount (delta)
         *
         * T   Type of object or function.
         * @param modifier function
         * @param object or getter function
         * @param property name _optional_
         * @param change amount (delta)
         * @param message _optional_
         */

        decreasesBy<T>(
            modifier: Function,
            object: T,
            property: string,
            /* keyof T */ change: number,
            message?: string,
        ): void;
        decreasesBy<T>(modifier: Function, object: T, change: number, message?: string): void;

        /**
         * Asserts that a function does not decrease an object property.
         *
         * T   Type of object.
         * @param modifier   Function to run.
         * @param object   Container object.
         * @param property   Property of object expected not to be decreased.
         * @param message   Message to display on error.
         */
        doesNotDecrease<T>(modifier: Function, object: T, property: string, /* keyof T */ message?: string): void;

        /**
         * Asserts that a function does not decreases a numeric object property or a function's return value by an amount (delta)
         *
         * T   Type of object or function.
         * @param modifier function
         * @param object or getter function
         * @param property name _optional_
         * @param change amount (delta)
         * @param message _optional_
         */

        doesNotDecreaseBy<T>(
            modifier: Function,
            object: T,
            property: string,
            /* keyof T */ change: number,
            message?: string,
        ): void;
        doesNotDecreaseBy<T>(modifier: Function, object: T, change: number, message?: string): void;

        /**
         * Asserts that a function does not decreases a numeric object property or a function's return value by an amount (delta)
         *
         * T   Type of object or function.
         * @param modifier function
         * @param object or getter function
         * @param property name _optional_
         * @param change amount (delta)
         * @param message _optional_
         */

        decreasesButNotBy<T>(
            modifier: Function,
            object: T,
            property: string,
            /* keyof T */ change: number,
            message?: string,
        ): void;
        decreasesButNotBy<T>(modifier: Function, object: T, change: number, message?: string): void;

        /**
         * Asserts if value is not a false value, and throws if it is a true value.
         *
         * T   Type of object.
         * @param object   Actual value.
         * @param message   Message to display on error.
         * @remarks This is added to allow for chai to be a drop-in replacement for
         *          Node’s assert class.
         */
        ifError<T>(object: T, message?: string): void;

        /**
         * Asserts that object is extensible (can have new properties added to it).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        isExtensible<T>(object: T, message?: string): void;

        /**
         * Asserts that object is extensible (can have new properties added to it).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        extensible<T>(object: T, message?: string): void;

        /**
         * Asserts that object is not extensible.
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        isNotExtensible<T>(object: T, message?: string): void;

        /**
         * Asserts that object is not extensible.
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        notExtensible<T>(object: T, message?: string): void;

        /**
         * Asserts that object is sealed (can have new properties added to it
         * and its existing properties cannot be removed).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        isSealed<T>(object: T, message?: string): void;

        /**
         * Asserts that object is sealed (can have new properties added to it
         * and its existing properties cannot be removed).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        sealed<T>(object: T, message?: string): void;

        /**
         * Asserts that object is not sealed.
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        isNotSealed<T>(object: T, message?: string): void;

        /**
         * Asserts that object is not sealed.
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        notSealed<T>(object: T, message?: string): void;

        /**
         * Asserts that object is frozen (cannot have new properties added to it
         * and its existing properties cannot be removed).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        isFrozen<T>(object: T, message?: string): void;

        /**
         * Asserts that object is frozen (cannot have new properties added to it
         * and its existing properties cannot be removed).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        frozen<T>(object: T, message?: string): void;

        /**
         * Asserts that object is not frozen (cannot have new properties added to it
         * and its existing properties cannot be removed).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        isNotFrozen<T>(object: T, message?: string): void;

        /**
         * Asserts that object is not frozen (cannot have new properties added to it
         * and its existing properties cannot be removed).
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        notFrozen<T>(object: T, message?: string): void;

        /**
         * Asserts that the target does not contain any values. For arrays and
         * strings, it checks the length property. For Map and Set instances, it
         * checks the size property. For non-function objects, it gets the count
         * of own enumerable string keys.
         *
         * T   Type of object
         * @param object   Actual value.
         * @param message   Message to display on error.
         */
        isEmpty<T>(object: T, message?: string): void;

        /**
         * Asserts that the target contains values. For arrays and strings, it checks
         * the length property. For Map and Set instances, it checks the size property.
         * For non-function objects, it gets the count of own enumerable string keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param message    Message to display on error.
         */
        isNotEmpty<T>(object: T, message?: string): void;

        /**
         * Asserts that `object` has at least one of the `keys` provided.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        hasAnyKeys<T>(object: T, keys: Array<Object | string> | { [key: string]: any }, message?: string): void;

        /**
         * Asserts that `object` has all and only all of the `keys` provided.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        hasAllKeys<T>(object: T, keys: Array<Object | string> | { [key: string]: any }, message?: string): void;

        /**
         * Asserts that `object` has all of the `keys` provided but may have more keys not listed.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        containsAllKeys<T>(object: T, keys: Array<Object | string> | { [key: string]: any }, message?: string): void;

        /**
         * Asserts that `object` has none of the `keys` provided.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        doesNotHaveAnyKeys<T>(object: T, keys: Array<Object | string> | { [key: string]: any }, message?: string): void;

        /**
         * Asserts that `object` does not have at least one of the `keys` provided.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        doesNotHaveAllKeys<T>(object: T, keys: Array<Object | string> | { [key: string]: any }, message?: string): void;

        /**
         * Asserts that `object` has at least one of the `keys` provided.
         * Since Sets and Maps can have objects as keys you can use this assertion to perform
         * a deep comparison.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        hasAnyDeepKeys<T>(object: T, keys: Array<Object | string> | { [key: string]: any }, message?: string): void;

        /**
         * Asserts that `object` has all and only all of the `keys` provided.
         * Since Sets and Maps can have objects as keys you can use this assertion to perform
         * a deep comparison.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        hasAllDeepKeys<T>(object: T, keys: Array<Object | string> | { [key: string]: any }, message?: string): void;

        /**
         * Asserts that `object` contains all of the `keys` provided.
         * Since Sets and Maps can have objects as keys you can use this assertion to perform
         * a deep comparison.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        containsAllDeepKeys<T>(
            object: T,
            keys: Array<Object | string> | { [key: string]: any },
            message?: string,
        ): void;

        /**
         * Asserts that `object` contains all of the `keys` provided.
         * Since Sets and Maps can have objects as keys you can use this assertion to perform
         * a deep comparison.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        doesNotHaveAnyDeepKeys<T>(
            object: T,
            keys: Array<Object | string> | { [key: string]: any },
            message?: string,
        ): void;

        /**
         * Asserts that `object` contains all of the `keys` provided.
         * Since Sets and Maps can have objects as keys you can use this assertion to perform
         * a deep comparison.
         * You can also provide a single object instead of a `keys` array and its keys
         * will be used as the expected set of keys.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param keys   Keys to check
         * @param message    Message to display on error.
         */
        doesNotHaveAllDeepKeys<T>(
            object: T,
            keys: Array<Object | string> | { [key: string]: any },
            message?: string,
        ): void;

        /**
         * Asserts that object has a direct or inherited property named by property,
         * which can be a string using dot- and bracket-notation for nested reference.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param property    Property to test.
         * @param message    Message to display on error.
         */
        nestedProperty<T>(object: T, property: string, message?: string): void;

        /**
         * Asserts that object does not have a property named by property,
         * which can be a string using dot- and bracket-notation for nested reference.
         * The property cannot exist on the object nor anywhere in its prototype chain.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param property    Property to test.
         * @param message    Message to display on error.
         */
        notNestedProperty<T>(object: T, property: string, message?: string): void;

        /**
         * Asserts that object has a property named by property with value given by value.
         * property can use dot- and bracket-notation for nested reference. Uses a strict equality check (===).
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param property    Property to test.
         * @param value    Value to test.
         * @param message    Message to display on error.
         */
        nestedPropertyVal<T>(object: T, property: string, value: any, message?: string): void;

        /**
         * Asserts that object does not have a property named by property with value given by value.
         * property can use dot- and bracket-notation for nested reference. Uses a strict equality check (===).
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param property    Property to test.
         * @param value    Value to test.
         * @param message    Message to display on error.
         */
        notNestedPropertyVal<T>(object: T, property: string, value: any, message?: string): void;

        /**
         * Asserts that object has a property named by property with a value given by value.
         * property can use dot- and bracket-notation for nested reference. Uses a deep equality check.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param property    Property to test.
         * @param value    Value to test.
         * @param message    Message to display on error.
         */
        deepNestedPropertyVal<T>(object: T, property: string, value: any, message?: string): void;

        /**
         * Asserts that object does not have a property named by property with value given by value.
         * property can use dot- and bracket-notation for nested reference. Uses a deep equality check.
         *
         * T   Type of object.
         * @param object   Object to test.
         * @param property    Property to test.
         * @param value    Value to test.
         * @param message    Message to display on error.
         */
        notDeepNestedPropertyVal<T>(object: T, property: string, value: any, message?: string): void;
    }

    export interface Config {
        /**
         * Default: false
         */
        includeStack: boolean;

        /**
         * Default: true
         */
        showDiff: boolean;

        /**
         * Default: 40
         */
        truncateThreshold: number;

        /**
         * Default: true
         */
        useProxy: boolean;

        /**
         * Default: ['then', 'catch', 'inspect', 'toJSON']
         */
        proxyExcludedKeys: string[];
    }

    export class AssertionError {
        constructor(message: string, _props?: any, ssf?: Function);
        name: string;
        message: string;
        showDiff: boolean;
        stack: string;
    }
}

declare const chai: Chai.ChaiStatic;

declare module "chai" {
    export = chai;
}

interface Object {
    should: Chai.Assertion;
}