starting to implement yarn 2 plug-n-play compatibility

.github/workflows/nodejs.yml

@@ -28,13 +28,18 @@ jobs:
         run: yarn deduplicate:check
 
   test:
-    name: Test on Node ${{ matrix.node }} and ${{ matrix.os }}
+    name: Test on Node ${{ matrix.node }} and ${{ matrix.os }}, yarn2?:${{ matrix.should_use_yarn2 }}
 
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         node: ['10.x', '12.x', '14.x']
         os: [ubuntu-latest, windows-latest, macOS-latest]
+        should_use_yarn2: [false]
+        include:
+          - node: '10.x'
+            os: ubuntu-latest
+            should_use_yarn2: true
 
     steps:
       - name: Checkout repo
@@ -47,5 +52,20 @@ jobs:
       - name: Install deps and build (with cache)
         uses: bahmutov/npm-install@v1
 
+      - name: Restore yarn2 cache
+        if: ${{ matrix.should_use_yarn2 }}
+        uses: actions/cache@v2
+        with:
+          path: |
+            test/yarn2/.yarn/cache
+            test/yarn2/yarn.lock
+          key: cache-key
+
+      - name: Setup for yarn2
+        if: ${{ matrix.should_use_yarn2 }}
+        run: |
+          echo 'yarnPath: .yarn/releases/yarn-sources.cjs' >> .yarnrc.yml && yarn && yarn node ./test/utils/prepare-for-yarn2.js && yarn && yarn --version
+
       - name: Test package
-        run: yarn test:post-build
+        run: |
+          yarn --version && yarn node -p 'process.versions.pnp' && yarn test:post-build

.gitignore

@@ -7,3 +7,10 @@ tester-react
 package-lock.json
 # Local Netlify folder
 .netlify
+
+# Files created when running tests under yarn2
+/.yarn
+!/.yarn/releases
+/.yarnrc.yml
+/.pnp.js
+

package.json

@@ -65,6 +65,7 @@
     "babel-plugin-transform-rename-import": "^2.3.0",
     "camelcase": "^6.0.0",
     "chalk": "^4.0.0",
+    "create-require": "^1.0.2",
     "enquirer": "^2.3.4",
     "eslint": "^6.1.0",
     "eslint-config-prettier": "^6.0.0",
@@ -77,7 +78,7 @@
     "eslint-plugin-react-hooks": "^2.2.0",
     "execa": "^4.0.3",
     "fs-extra": "^9.0.0",
-    "jest": "^25.3.0",
+    "jest": "^25.4.0",
     "jest-watch-typeahead": "^0.5.0",
     "jpjs": "^1.2.1",
     "lodash.merge": "^4.6.2",
@@ -94,11 +95,12 @@
     "semver": "^7.1.1",
     "shelljs": "^0.8.3",
     "tiny-glob": "^0.2.6",
-    "ts-jest": "^25.3.1",
+    "ts-jest": "^25.5.1",
     "tslib": "^1.9.3",
-    "typescript": "^3.7.3"
+    "typescript": "3.7.3"
   },
   "devDependencies": {
+    "@jest/types": "^25.4.0",
     "@types/eslint": "^6.1.2",
     "@types/fs-extra": "^9.0.1",
     "@types/lodash": "^4.14.161",
@@ -114,6 +116,7 @@
     "cssnano": "^4.1.10",
     "doctoc": "^1.4.0",
     "husky": "^4.2.2",
+    "lodash": "^4.17.20",
     "np": "^6.4.0",
     "pretty-quick": "^2.0.0",
     "react": "^16.8.6",
@@ -123,6 +126,7 @@
     "styled-components": "^5.0.1",
     "tiny-invariant": "^1.1.0",
     "tiny-warning": "^1.0.3",
+    "type-fest": "^0.13.1",
     "yarn-deduplicate": "^2.1.1"
   },
   "husky": {

src/createJestConfig.ts

@@ -1,15 +1,39 @@
 import { Config } from '@jest/types';
+import path from 'path';
+import createRequire from 'create-require';
 
 export type JestConfigOptions = Partial<Config.InitialOptions>;
 
 export function createJestConfig(
   _: (relativePath: string) => void,
   rootDir: string
 ): JestConfigOptions {
+  function resolveRelativeTo(file: string, moduleSpecifier: string) {
+    const req = createRequire(file);
+    try {
+      return req.resolve(moduleSpecifier);
+    } catch {
+      return null;
+    }
+  }
+  function resolveBabelJest() {
+    const jestLocation =
+      resolveRelativeTo(path.join(rootDir, 'file.js'), 'jest') ||
+      require.resolve('jest');
+    const jestCoreLocation = resolveRelativeTo(jestLocation, '@jest/core')!;
+    const jestConfigLocation = resolveRelativeTo(
+      jestCoreLocation,
+      'jest-config'
+    )!;
+    return (
+      resolveRelativeTo(path.join(rootDir, 'file.js'), 'babel-jest') ||
+      resolveRelativeTo(jestConfigLocation, 'babel-jest')!
+    );
+  }
   const config: JestConfigOptions = {
     transform: {
       '.(ts|tsx)$': require.resolve('ts-jest/dist'),
-      '.(js|jsx)$': require.resolve('babel-jest'), // jest's default
+      '.(js|jsx)$': resolveBabelJest(), // jest's default
     },
     transformIgnorePatterns: ['[/\\\\]node_modules[/\\\\].+\\.(js|jsx)$'],
     moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],

test/utils/fixture.ts

@@ -5,6 +5,10 @@ export const rootDir = process.cwd();
 
 shell.config.silent = true;
 
+export function isYarn2() {
+  return !!process.versions.pnp;
+}
+
 export function setupStageWithFixture(
   testDir: string,
   stageName: string,
@@ -15,11 +19,13 @@ export function setupStageWithFixture(
   shell.exec(
     `cp -a ${rootDir}/test/${testDir}/fixtures/${fixtureName}/. ${stagePath}/`
   );
-  shell.ln(
-    '-s',
-    path.join(rootDir, 'node_modules'),
-    path.join(stagePath, 'node_modules')
-  );
+  if (!isYarn2()) {
+    shell.ln(
+      '-s',
+      path.join(rootDir, 'node_modules'),
+      path.join(stagePath, 'node_modules')
+    );
+  }
   shell.cd(stagePath);
 }
 

test/utils/prepare-for-yarn2.js

@@ -0,0 +1,37 @@
+/*
+ * yarn 2 requires each package.json to declare the dependencies used by files within its subdirectory.
+ * tsdx tests are written to use the exact same set of dependencies as the root package.json.
+ *
+ * Before running tests under yarn2 PnP, we copy all dependencies and devDependencies from the root
+ * to each sub-package.json.  We also declare these subdirectories as workspaces so `yarn`
+ * recognizes and resolves them all.
+ */
+
+const fs = require('fs-extra');
+const shell = require('shelljs');
+
+shell.cd(__dirname);
+shell.cd('../..');
+const rootPkg = fs.readJSONSync('package.json');
+// Declare all stages as workspaces so that a single `yarn` invocation resolves them all.
+rootPkg.workspaces = {
+  workspaces: ['test/e2e/fixtures/*', 'test/integration/fixtures/*', 'stage-*'],
+};
+fs.writeJSONSync('package.json', rootPkg, { spaces: 2 });
+
+// Copy all root dependencies onto each test package.json
+for (const pkgPath of [
+  shell.ls('test/e2e/fixtures/*/package.json'),
+  shell.ls('test/integration/fixtures/*/package.json'),
+]
+  .join(',')
+  .split(',')) {
+  const pkg = fs.readJSONSync(`./${pkgPath}`);
+  pkg.dependencies = Object.assign({}, pkg.dependencies, rootPkg.dependencies);
+  pkg.devDependencies = Object.assign(
+    {},
+    pkg.devDependencies,
+    rootPkg.devDependencies
+  );
+  fs.writeJSONSync(pkgPath, pkg, { spaces: 2 });
+}