[MI-3827]: RTL base setup + downgrade to react 17

.gitignore

@@ -12,3 +12,4 @@ bin/
 
 node_modules
 
+coverage

webapp/babel.config.js

@@ -0,0 +1,44 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+const config = {
+    presets: [
+        ['@babel/preset-env', {
+            targets: {
+                chrome: 66,
+                firefox: 60,
+                edge: 42,
+                safari: 12,
+            },
+            modules: false,
+            corejs: 3,
+            debug: false,
+            useBuiltIns: 'usage',
+            shippedProposals: true,
+        }],
+        ['@babel/preset-react', {
+            useBuiltIns: true,
+        }],
+        ['@babel/typescript', {
+            allExtensions: true,
+            isTSX: true,
+        }],
+    ],
+    plugins: [
+        '@babel/plugin-proposal-class-properties',
+        '@babel/plugin-syntax-dynamic-import',
+        '@babel/plugin-proposal-optional-chaining',
+        'babel-plugin-typescript-to-proptypes',
+    ],
+};
+
+// Jest needs module transformation
+config.env = {
+    test: {
+        presets: config.presets,
+        plugins: config.plugins,
+    },
+};
+config.env.test.presets[0][1].modules = 'auto';
+
+module.exports = config;

webapp/jest.config.ts

@@ -0,0 +1,227 @@
+/**
+ * For a detailed explanation regarding each configuration property, visit:
+ * https://jestjs.io/docs/configuration
+ */
+
+import type {Config} from 'jest';
+
+const config: Config = {
+
+    // All imported modules in your tests should be mocked automatically
+    // automock: false,
+
+    // Stop running tests after `n` failures
+    // bail: 0,
+
+    // The directory where Jest should store its cached dependency information
+    // cacheDirectory: "/tmp/jest_rs",
+
+    // Automatically clear mock calls, instances, contexts and results before every test
+    clearMocks: true,
+
+    // Indicates whether the coverage information should be collected while executing the test
+    collectCoverage: true,
+
+    // An array of glob patterns indicating a set of files for which coverage information should be collected
+    collectCoverageFrom: [
+        'src/components/**/*.{jsx,tsx}',
+        'src/reducers/**/*.{js,jsx,ts,tsx}',
+        'src/containers/**/*.{js,jsx,ts,tsx}',
+    ],
+
+    // The directory where Jest should output its coverage files
+    coverageDirectory: 'coverage',
+
+    // An array of regexp pattern strings used to skip coverage collection
+    // coveragePathIgnorePatterns: [
+    //   "/node_modules/"
+    // ],
+
+    // Indicates which provider should be used to instrument code for coverage
+    // coverageProvider: "babel",
+
+    // A list of reporter names that Jest uses when writing coverage reports
+    // coverageReporters: [
+    //   "json",
+    //   "text",
+    //   "lcov",
+    //   "clover"
+    // ],
+
+    // An object that configures minimum threshold enforcement for coverage results
+    // coverageThreshold: undefined,
+
+    // A path to a custom dependency extractor
+    // dependencyExtractor: undefined,
+
+    // Make calling deprecated APIs throw helpful error messages
+    // errorOnDeprecated: false,
+
+    // The default configuration for fake timers
+    // fakeTimers: {
+    //   "enableGlobally": false
+    // },
+
+    // Force coverage collection from ignored files using an array of glob patterns
+    // forceCoverageMatch: [],
+
+    // A path to a module which exports an async function that is triggered once before all test suites
+    // globalSetup: undefined,
+
+    // A path to a module which exports an async function that is triggered once after all test suites
+    // globalTeardown: undefined,
+
+    // A set of global variables that need to be available in all test environments
+    // globals: {},
+
+    // The maximum amount of workers used to run your tests. Can be specified as % or a number. E.g. maxWorkers: 10% will use 10% of your CPU amount + 1 as the maximum worker number. maxWorkers: 2 will use a maximum of 2 workers.
+    // maxWorkers: "50%",
+
+    // An array of directory names to be searched recursively up from the requiring module's location
+    moduleDirectories: [
+        'node_modules',
+    ],
+
+    // An array of file extensions your modules use
+    // moduleFileExtensions: [
+    //   "js",
+    //   "mjs",
+    //   "cjs",
+    //   "jsx",
+    //   "ts",
+    //   "tsx",
+    //   "json",
+    //   "node"
+    // ],
+    moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx'],
+
+    // A map from regular expressions to module names or to arrays of module names that allow to stub out resources with a single module
+    moduleNameMapper: {
+        '^.+\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$': 'identity-obj-proxy',
+        '^.+\\.(css|less|scss)$': 'identity-obj-proxy',
+        '^src/(.*)': '<rootDir>/src/$1',
+        '^components/(.*)': '<rootDir>/src/components/$1',
+        '^constants/(.*)': '<rootDir>/src/constants/$1',
+        '^components': '<rootDir>/src/components/$1',
+        '^utils': '<rootDir>/src/utils/$1',
+        '^selectors': '<rootDir>/src/selectors/$1',
+        '^hooks/(.*)': '<rootDir>/src/hooks/$1',
+        '^reducers/(.*)': '<rootDir>/src/reducers/$1',
+        '^services': '<rootDir>/src/services/$1',
+    },
+
+    // An array of regexp pattern strings, matched against all module paths before considered 'visible' to the module loader
+    // modulePathIgnorePatterns: [],
+
+    // Activates notifications for test results
+    // notify: false,
+
+    // An enum that specifies notification mode. Requires { notify: true }
+    // notifyMode: "failure-change",
+
+    // A preset that is used as a base for Jest's configuration
+    preset: 'ts-jest',
+
+    // Run tests from one or more projects
+    // projects: undefined,
+
+    // Use this configuration option to add custom reporters to Jest
+    // reporters: undefined,
+
+    // Automatically reset mock state before every test
+    // resetMocks: false,
+
+    // Reset the module registry before running each individual test
+    // resetModules: false,
+
+    // A path to a custom resolver
+    // resolver: undefined,
+
+    // Automatically restore mock state and implementation before every test
+    // restoreMocks: false,
+
+    // The root directory that Jest should scan for tests and modules within
+    // rootDir: undefined,
+
+    // A list of paths to directories that Jest should use to search for files in
+    // roots: [
+    //   "<rootDir>"
+    // ],
+    roots: ['<rootDir>/src/'],
+
+    // Allows you to use a custom runner instead of Jest's default test runner
+    // runner: "jest-runner",
+
+    // The paths to modules that run some code to configure or set up the testing environment before each test
+    // setupFiles: [],
+
+    // A list of paths to modules that run some code to configure or set up the testing framework before each test
+    // setupFilesAfterEnv: [],
+    setupFilesAfterEnv: [
+        '@testing-library/jest-dom',
+        '<rootDir>/src/tests/setup.ts',
+    ],
+
+    // The number of seconds after which a test is considered as slow and reported as such in the results.
+    // slowTestThreshold: 5,
+
+    // A list of paths to snapshot serializer modules Jest should use for snapshot testing
+    // snapshotSerializers: [],
+
+    // The test environment that will be used for testing
+    testEnvironment: 'jsdom',
+
+    // Options that will be passed to the testEnvironment
+    // testEnvironmentOptions: {},
+
+    // Adds a location field to test results
+    // testLocationInResults: false,
+
+    // The glob patterns Jest uses to detect test files
+    // testMatch: [
+    //   "**/__tests__/**/*.[jt]s?(x)",
+    //   "**/?(*.)+(spec|test).[tj]s?(x)"
+    // ],
+
+    // An array of regexp pattern strings that are matched against all test paths, matched tests are skipped
+    // testPathIgnorePatterns: [
+    //   "/node_modules/"
+    // ],
+
+    // The regexp pattern or array of patterns that Jest uses to detect test files
+    // testRegex: [],
+
+    // This option allows the use of a custom results processor
+    // testResultsProcessor: undefined,
+
+    // This option allows use of a custom test runner
+    // testRunner: "jest-circus/runner",
+
+    // A map from regular expressions to paths to transformers
+    transform: {
+        '\\.[jt]sx?$': 'babel-jest',
+    },
+
+    // An array of regexp pattern strings that are matched against all source file paths, matched files will skip transformation
+    // transformIgnorePatterns: [
+    //   "/node_modules/",
+    //   "\\.pnp\\.[^\\/]+$"
+    // ],
+    transformIgnorePatterns: [
+        'node_modules/(?!(react-native|react-router|@brightscout)/)',
+    ],
+
+    // An array of regexp pattern strings that are matched against all modules before the module loader will automatically return a mock for them
+    // unmockedModulePathPatterns: undefined,
+
+    // Indicates whether each individual test should be reported during the run
+    // verbose: undefined,
+
+    // An array of regexp patterns that are matched against all source file paths before re-running tests in watch mode
+    // watchPathIgnorePatterns: [],
+
+    // Whether to use watchman for file crawling
+    // watchman: true,
+};
+
+export default config;