@types/jest-image-snapshot/index.d.ts

// Type definitions for jest-image-snapshot 4.1
// Project: https://github.com/americanexpress/jest-image-snapshot#readme
// Definitions by: Janeene Beeforth <https://github.com/dawnmist>
//                 erbridge <https://github.com/erbridge>
//                 Piotr Błażejewicz <https://github.com/peterblazejewicz>
// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
// TypeScript Version: 3.1

/// <reference types="jest" />
import { PixelmatchOptions } from 'pixelmatch';
import { Options as SSIMOptions } from 'ssim.js';

export interface MatchImageSnapshotOptions {
    /**
     * If set to true, the build will not fail when the screenshots to compare have different sizes.
     * @default false
     */
    allowSizeMismatch?: boolean;
    /**
     * Custom config passed to 'pixelmatch' or 'ssim'
     */
    customDiffConfig?: PixelmatchOptions | SSIMOptions;
    /**
     * The method by which images are compared.
     * `pixelmatch` does a pixel by pixel comparison, whereas `ssim` does a structural similarity comparison.
     * @default 'pixelmatch'
     */
    comparisonMethod?: 'pixelmatch' | 'ssim';
    /**
     * Custom snapshots directory.
     * Absolute path of a directory to keep the snapshot in.
     */
    customSnapshotsDir?: string;
    /**
     * A custom absolute path of a directory to keep this diff in
     */
    customDiffDir?: string;
    /**
     * A custom name to give this snapshot. If not provided, one is computed automatically. When a function is provided
     * it is called with an object containing testPath, currentTestName, counter and defaultIdentifier as its first
     * argument. The function must return an identifier to use for the snapshot.
     */
    customSnapshotIdentifier?:
        | ((parameters: {
              testPath: string;
              currentTestName: string;
              counter: number;
              defaultIdentifier: string;
          }) => string)
        | string;
    /**
     * Changes diff image layout direction.
     * @default 'horizontal'
     */
    diffDirection?: 'horizontal' | 'vertical';
    /**
     * Will output base64 string of a diff image to console in case of failed tests (in addition to creating a diff image).
     * This string can be copy-pasted to a browser address string to preview the diff for a failed test.
     * @default false
     */
    dumpDiffToConsole?: boolean;
    /**
     * Removes coloring from the console output, useful if storing the results to a file.
     * @default false.
     */
    noColors?: boolean;
    /**
     * Sets the threshold that would trigger a test failure based on the failureThresholdType selected. This is different
     * to the customDiffConfig.threshold above - the customDiffConfig.threshold is the per pixel failure threshold, whereas
     * this is the failure threshold for the entire comparison.
     * @default 0.
     */
    failureThreshold?: number;
    /**
     * Sets the type of threshold that would trigger a failure.
     * @default 'pixel'.
     */
    failureThresholdType?: 'pixel' | 'percent';
    /**
     * Updates a snapshot even if it passed the threshold against the existing one.
     * @default false.
     */
    updatePassedSnapshot?: boolean;
    /**
     * Applies Gaussian Blur on compared images, accepts radius in pixels as value. Useful when you have noise after
     * scaling images per different resolutions on your target website, usually setting its value to 1-2 should be
     * enough to solve that problem.
     * @default 0.
     */
    blur?: number;
    /**
     * Runs the diff in process without spawning a child process.
     * @default false.
     */
    runInProcess?: boolean;
}

/**
 * Function to be passed to jest's expect.extend.
 * Example:
 *   import { toMatchImageSnapshot } from 'jest-image-snapshot';
 *   expect.extend({ toMatchImageSnapshot });
 */
export function toMatchImageSnapshot(options?: MatchImageSnapshotOptions): { message(): string; pass: boolean };

/**
 * Configurable function that can be passed to jest's expect.extend.
 * Example:
 *   import { configureToMatchImageSnapshot } from 'jest-image-snapshot';
 *   const toMatchImageSnapshot = configureToMatchImageSnapshot({ noColors: true });
 *   expect.extend({ toMatchImageSnapshot });
 */
export function configureToMatchImageSnapshot(
    options: MatchImageSnapshotOptions,
): () => { message(): string; pass: boolean };

/**
 * Mutates original state with new state
 */
export function updateSnapshotState<TObject, TPartial>(originalSnapshotState: TObject, partialSnapshotState: TPartial): TObject & TPartial;

declare global {
    namespace jest {
        interface Matchers<R, T> {
            toMatchImageSnapshot(options?: MatchImageSnapshotOptions): R;
        }
    }
}