-- ROBLOX upstream: https://github.com/facebook/react/blob/v17.0.1/packages/react-devtools-shared/src/__tests__/events-test.js
-- /**
--  * Copyright (c) Facebook, Inc. and its affiliates.
--  *
--  * This source code is licensed under the MIT license found in the
--  *
--  * LICENSE file in the root directory of this source tree.
--  * @flow
--  */

local Packages = script.Parent.Parent.Parent
local Error = require(Packages.LuauPolyfill).Error
local JestGlobals = require(Packages.Dev.JestGlobals)
local describe = JestGlobals.describe
local it = JestGlobals.it
local beforeEach = JestGlobals.beforeEach
local jestExpect = JestGlobals.expect
local jest = JestGlobals.jest

describe("events", function()
	local dispatcher
	beforeEach(function()
		jest.resetModules()
		local EventEmitter = require(script.Parent.Parent.events)
		dispatcher = EventEmitter.new()
	end)

	it("can dispatch an event with no listeners", function()
		dispatcher:emit("event", 123)
	end)

	it("handles a listener being attached multiple times", function()
		local callback = jest.fn()
		dispatcher:addListener("event", callback)
		dispatcher:addListener("event", callback)
		dispatcher:emit("event", 123)
		jestExpect(callback).toHaveBeenCalledTimes(1)
		jestExpect(callback).toHaveBeenCalledWith(123)
	end)

	it("notifies all attached listeners of events", function()
		local callback1 = jest.fn()
		local callback2 = jest.fn()
		local callback3 = jest.fn()
		dispatcher:addListener("event", callback1)
		dispatcher:addListener("event", callback2)
		dispatcher:addListener("other-event", callback3)
		dispatcher:emit("event", 123)
		jestExpect(callback1).toHaveBeenCalledTimes(1)
		jestExpect(callback1).toHaveBeenCalledWith(123)
		jestExpect(callback2).toHaveBeenCalledTimes(1)
		jestExpect(callback2).toHaveBeenCalledWith(123)
		jestExpect(callback3).never.toHaveBeenCalled()
	end)

	it("calls later listeners before re-throwing if an earlier one throws", function()
		local callbackThatThrows = jest.fn(function()
			error(Error.new("expected"))
		end)
		local callback = jest.fn()
		dispatcher:addListener("event", callbackThatThrows)
		dispatcher:addListener("event", callback)
		jestExpect(function()
			dispatcher:emit("event", 123)
		end).toThrow("expected")
		jestExpect(callbackThatThrows).toHaveBeenCalledTimes(1)
		jestExpect(callbackThatThrows).toHaveBeenCalledWith(123)
		jestExpect(callback).toHaveBeenCalledTimes(1)
		jestExpect(callback).toHaveBeenCalledWith(123)
	end)

	it("removes attached listeners", function()
		local callback1 = jest.fn()
		local callback2 = jest.fn()
		dispatcher:addListener("event", callback1)
		dispatcher:addListener("other-event", callback2)
		dispatcher:removeListener("event", callback1)
		dispatcher:emit("event", 123)
		jestExpect(callback1).never.toHaveBeenCalled()
		dispatcher:emit("other-event", 123)
		jestExpect(callback2).toHaveBeenCalledTimes(1)
		jestExpect(callback2).toHaveBeenCalledWith(123)
	end)

	it("removes all listeners", function()
		local callback1 = jest.fn()
		local callback2 = jest.fn()
		local callback3 = jest.fn()
		dispatcher:addListener("event", callback1)
		dispatcher:addListener("event", callback2)
		dispatcher:addListener("other-event", callback3)
		dispatcher:removeAllListeners()
		dispatcher:emit("event", 123)
		dispatcher:emit("other-event", 123)
		jestExpect(callback1).never.toHaveBeenCalled()
		jestExpect(callback2).never.toHaveBeenCalled()
		jestExpect(callback3).never.toHaveBeenCalled()
	end)

	it(
		"should call the initial listeners even if others are added or removed during a dispatch",
		function()
			local callback2, callback3
			local callback1 = jest.fn(function()
				dispatcher:removeListener("event", callback2)
				dispatcher:addListener("event", callback3)
			end)
			callback2 = jest.fn()
			callback3 = jest.fn()
			dispatcher:addListener("event", callback1)
			dispatcher:addListener("event", callback2)
			dispatcher:emit("event", 123)
			jestExpect(callback1).toHaveBeenCalledTimes(1)
			jestExpect(callback1).toHaveBeenCalledWith(123)
			jestExpect(callback2).toHaveBeenCalledTimes(1)
			jestExpect(callback2).toHaveBeenCalledWith(123)
			jestExpect(callback3).never.toHaveBeenCalled()
			dispatcher:emit("event", 456)
			jestExpect(callback1).toHaveBeenCalledTimes(2)
			jestExpect(callback1).toHaveBeenCalledWith(456)
			jestExpect(callback2).toHaveBeenCalledTimes(1)
			jestExpect(callback3).toHaveBeenCalledTimes(1)
			jestExpect(callback3).toHaveBeenCalledWith(456)
		end
	)
end)