chore: migrate jest-resolve to TypeScript

[SimenB]

Summary

As expected, had to tweak jest-haste-map's types a bit to match undefined | null stuff. Can revisit later and be more consistent across the board

Built diff:

diff --git c/packages/jest-resolve/build/defaultResolver.js w/packages/jest-resolve/build/defaultResolver.js
index fab1abcb1..60db7374c 100644
--- c/packages/jest-resolve/build/defaultResolver.js
+++ w/packages/jest-resolve/build/defaultResolver.js
@@ -5,30 +5,30 @@ Object.defineProperty(exports, '__esModule', {
 });
 exports.default = defaultResolver;
 
-function _browserResolve() {
-  const data = _interopRequireDefault(require('browser-resolve'));
+function _fs() {
+  const data = _interopRequireDefault(require('fs'));
 
-  _browserResolve = function _browserResolve() {
+  _fs = function _fs() {
     return data;
   };
 
   return data;
 }
 
-function _fs() {
-  const data = _interopRequireDefault(require('fs'));
+function _path() {
+  const data = _interopRequireDefault(require('path'));
 
-  _fs = function _fs() {
+  _path = function _path() {
     return data;
   };
 
   return data;
 }
 
-function _path() {
-  const data = _interopRequireDefault(require('path'));
+function _browserResolve() {
+  const data = _interopRequireDefault(require('browser-resolve'));
 
-  _path = function _path() {
+  _browserResolve = function _browserResolve() {
     return data;
   };
 
@@ -48,8 +48,6 @@ function _interopRequireDefault(obj) {
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- *
  */
 function defaultResolver(path, options) {
   const resolve = options.browser
diff --git c/packages/jest-resolve/build/index.js w/packages/jest-resolve/build/index.js
index a397e5f2b..af3a8dfdb 100644
--- c/packages/jest-resolve/build/index.js
+++ w/packages/jest-resolve/build/index.js
@@ -20,12 +20,6 @@ function _realpathNative() {
   return data;
 }
 
-var _nodeModulesPaths = _interopRequireDefault(require('./nodeModulesPaths'));
-
-var _isBuiltinModule = _interopRequireDefault(require('./isBuiltinModule'));
-
-var _defaultResolver = _interopRequireDefault(require('./defaultResolver'));
-
 function _chalk() {
   const data = _interopRequireDefault(require('chalk'));
 
@@ -36,6 +30,12 @@ function _chalk() {
   return data;
 }
 
+var _nodeModulesPaths = _interopRequireDefault(require('./nodeModulesPaths'));
+
+var _isBuiltinModule = _interopRequireDefault(require('./isBuiltinModule'));
+
+var _defaultResolver = _interopRequireDefault(require('./defaultResolver'));
+
 function _interopRequireDefault(obj) {
   return obj && obj.__esModule ? obj : {default: obj};
 }
@@ -45,8 +45,6 @@ function _interopRequireDefault(obj) {
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- *
  */
 const NATIVE_PLATFORM = 'native'; // We might be inside a symlink.
 
diff --git c/packages/jest-resolve/build/isBuiltinModule.js w/packages/jest-resolve/build/isBuiltinModule.js
index 9ae6e31ef..a4c9f5035 100644
--- c/packages/jest-resolve/build/isBuiltinModule.js
+++ w/packages/jest-resolve/build/isBuiltinModule.js
@@ -5,29 +5,30 @@ Object.defineProperty(exports, '__esModule', {
 });
 exports.default = isBuiltinModule;
 
-function _module() {
-  const data = require('module');
+function _module2() {
+  const data = _interopRequireDefault(require('module'));
 
-  _module = function _module() {
+  _module2 = function _module2() {
     return data;
   };
 
   return data;
 }
 
+function _interopRequireDefault(obj) {
+  return obj && obj.__esModule ? obj : {default: obj};
+}
+
 /**
  * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- *
  */
-// $FlowFixMe: Flow doesn't know about the `module` module
 const EXPERIMENTAL_MODULES = ['worker_threads'];
 const BUILTIN_MODULES = new Set(
-  _module().builtinModules
-    ? _module().builtinModules.concat(EXPERIMENTAL_MODULES)
+  _module2().default.builtinModules
+    ? _module2().default.builtinModules.concat(EXPERIMENTAL_MODULES)
     : Object.keys(process.binding('natives'))
         .filter(module => !/^internal\//.test(module))
         .concat(EXPERIMENTAL_MODULES)
diff --git c/packages/jest-resolve/build/nodeModulesPaths.js w/packages/jest-resolve/build/nodeModulesPaths.js
index c3bef18cd..8d9d10f0c 100644
--- c/packages/jest-resolve/build/nodeModulesPaths.js
+++ w/packages/jest-resolve/build/nodeModulesPaths.js
@@ -36,13 +36,11 @@ function _interopRequireDefault(obj) {
  * LICENSE file in the root directory of this source tree.
  *
  * Adapted from: https://github.com/substack/node-resolve
- *
- *
  */
 function nodeModulesPaths(basedir, options) {
   const modules =
     options && options.moduleDirectory
-      ? [].concat(options.moduleDirectory)
+      ? Array.from(options.moduleDirectory)
       : ['node_modules']; // ensure that `basedir` is an absolute path at this point,
   // resolving against the process' current working directory
 
diff --git c/packages/jest-resolve/build/types.js w/packages/jest-resolve/build/types.js
new file mode 100644
index 000000000..ad9a93a7c
--- /dev/null
+++ w/packages/jest-resolve/build/types.js
@@ -0,0 +1 @@
+'use strict';

Test plan

Green CI

[SimenB]

I think this makes the most sense - the constructor of jest-resolve takes ModuleMap from jest-haste-map. So both for types but also for usage, we need to ensure that the API is what we expect it to be

[codecov-io]

Codecov Report

Merging #7871 into master will decrease coverage by 0.27%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7871      +/-   ##
==========================================
- Coverage   58.41%   58.14%   -0.28%     
==========================================
  Files         178      174       -4     
  Lines        6630     6424     -206     
  Branches        5        6       +1     
==========================================
- Hits         3873     3735     -138     
+ Misses       2755     2687      -68     
  Partials        2        2

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[jeysal]

built haste-map index.d.ts:

import HasteFS from './HasteFS';
import HasteModuleMap, { SerializableModuleMap as HasteSerializableModuleMap } from './ModuleMap';
export declare type ModuleMap = HasteModuleMap;
export declare type SerializableModuleMap = HasteSerializableModuleMap;
export declare type FS = HasteFS;

totally missing the main export.
Working on how to fix this atm

[jeysal]

I'm not sure we can fix this without dropping the export types at the top of haste map. Basically, we want both export = HasteMap (because making it the default export like it should be would be breaking) and export type .... It would be fine for a normal property (can just put it on the class), but I don't know how we could possibly put types onto HasteMap

[SimenB]

Thanks for digging! I say we keep it as is then, and try to go for a real ESM run at some point in the future.

It's easier with modules like haste map anyways since it's mostly internal and not pluggable like other parts of Jest are

[jeysal]

Guess the ModuleMap and HasteFS types are more important anyway, they're the ones used in Context etc

[thymikee]

Awesome

[github-actions]

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