Migrate initial few packages to TypeScript (facebook#2110)

* Add initial test migration

* Fix failing integrity check

* Remove ts-nochecks

* Update test config

* Add babel typescript preset instead of rollup plugin

* Remove relative paths for unit tests

* Small requested changes

.eslintrc.js

@@ -56,6 +56,10 @@ module.exports = {
         sourceType: 'module',
       },
       plugins: ['react', '@typescript-eslint'],
+      rules: {
+        '@typescript-eslint/ban-ts-comment': OFF,
+        '@typescript-eslint/no-unused-vars': [ERROR, {args: 'none'}],
+      },
     },
   ],
 

.flowconfig

@@ -19,6 +19,7 @@ exact_by_default=true
 
 module.name_mapper='^lexical$' -> '<PROJECT_ROOT>/packages/lexical/flow/Lexical.js.flow'
 
+module.name_mapper='^@lexical/clipboard' -> '<PROJECT_ROOT>/packages/lexical-clipboard/flow/LexicalClipboard.js.flow'
 module.name_mapper='^@lexical/list' -> '<PROJECT_ROOT>/packages/lexical-list/flow/LexicalList.js.flow'
 module.name_mapper='^@lexical/table' -> '<PROJECT_ROOT>/packages/lexical-table/flow/LexicalTable.js.flow'
 module.name_mapper='^@lexical/file' -> '<PROJECT_ROOT>/packages/lexical-file/flow/LexicalFile.js.flow'

jest.config.js

@@ -17,17 +17,21 @@ module.exports = {
       ...common,
       displayName: 'unit',
       globals: {
+        IS_REACT_ACT_ENVIRONMENT: true,
         __DEV__: true,
+        'ts-jest': {
+          tsconfig: 'tsconfig.test.json',
+        },
       },
       moduleNameMapper: {
         '^./dist/(.+)': './src/$1',
         '^@lexical/clipboard$':
           '<rootDir>/packages/lexical-clipboard/src/index.js',
-        '^@lexical/code$': '<rootDir>/packages/lexical-code/src/index.js',
-        '^@lexical/dragon$': '<rootDir>/packages/lexical-dragon/src/index.js',
+        '^@lexical/code$': '<rootDir>/packages/lexical-code/src/index.ts',
+        '^@lexical/dragon$': '<rootDir>/packages/lexical-dragon/src/index.ts',
         '^@lexical/file$': '<rootDir>/packages/lexical-file/src/index.js',
         '^@lexical/hashtag$': '<rootDir>/packages/lexical-hashtag/src/index.js',
-        '^@lexical/history$': '<rootDir>/packages/lexical-history/src/index.js',
+        '^@lexical/history$': '<rootDir>/packages/lexical-history/src/index.ts',
         '^@lexical/link$': '<rootDir>/packages/lexical-link/src/index.js',
         '^@lexical/list$': '<rootDir>/packages/lexical-list/src/index.js',
         '^@lexical/mark$': '<rootDir>/packages/lexical-mark/src/index.js',
@@ -85,7 +89,13 @@ module.exports = {
         formatProdErrorMessage:
           '<rootDir>/scripts/error-codes/formatProdErrorMessage.js',
       },
-      testMatch: ['**/__tests__/unit/**/*.test.js'],
+      preset: 'ts-jest',
+      testEnvironment: 'jsdom',
+      testMatch: ['**/__tests__/unit/**/*.test{.ts,.js}'],
+      transform: {
+        '^.+\\.jsx?$': 'babel-jest',
+        '^.+\\.tsx$': 'ts-jest',
+      },
     },
     {
       ...common,