fix(jest-resolve): don't confuse directories with files

CHANGELOG.md

@@ -10,6 +10,7 @@
 - `[jest-config]` Treat `setupFilesAfterEnv` like `setupFiles` when normalizing configs against presets ([#9495](https://github.com/facebook/jest/pull/9495))
 - `[jest-matcher-utils]` Fix diff highlight of symbol-keyed object. ([#9499](https://github.com/facebook/jest/pull/9499))
 - `[jest-resolve]` Fix module identity preservation with symlinks and browser field resolution ([#9511](https://github.com/facebook/jest/pull/9511))
+- `[jest-resolve]` Do not confuse directories with files ([#8912](https://github.com/facebook/jest/pull/8912))
 - `[jest-snapshot]` Downgrade semver to v6 to support node 8 ([#9451](https://github.com/facebook/jest/pull/9451))
 - `[jest-transform]` Correct sourcemap behavior for transformed and instrumented code ([#9460](https://github.com/facebook/jest/pull/9460))
 - `[pretty-format]` Export `OldPlugin` type ([#9491](https://github.com/facebook/jest/pull/9491))

packages/jest-resolve/package.json

@@ -15,7 +15,7 @@
     "chalk": "^3.0.0",
     "jest-pnp-resolver": "^1.2.1",
     "realpath-native": "^2.0.0",
-    "resolve": "^1.15.0"
+    "resolve": "^1.15.1"
   },
   "devDependencies": {
     "@types/browser-resolve": "^0.0.5",

packages/jest-resolve/src/__mocks__/foo/foo.js

@@ -0,0 +1,8 @@
+/**
+ * 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.
+ */
+
+module.exports = require.resolve('./');

packages/jest-resolve/src/__tests__/resolve.test.ts

@@ -156,6 +156,20 @@ describe('resolveModule', () => {
     });
     expect(resolved).toBe(require.resolve('../__mocks__/mockJsDependency.js'));
   });
+
+  it('does not confuse directories with files', () => {
+    const resolver = new Resolver(moduleMap, {
+      extensions: ['.js'],
+    } as ResolverConfig);
+    const mocksDirectory = path.resolve(__dirname, '../__mocks__');
+    const fooSlashFoo = path.join(mocksDirectory, 'foo/foo.js');
+    const fooSlashIndex = path.join(mocksDirectory, 'foo/index.js');
+
+    const resolvedWithSlash = resolver.resolveModule(fooSlashFoo, './');
+    const resolvedWithDot = resolver.resolveModule(fooSlashFoo, '.');
+    expect(resolvedWithSlash).toBe(fooSlashIndex);
+    expect(resolvedWithSlash).toBe(resolvedWithDot);
+  });
 });
 
 describe('getMockModule', () => {

yarn.lock

@@ -12567,10 +12567,10 @@ resolve@1.1.7:
   resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.1.7.tgz#203114d82ad2c5ed9e8e0411b3932875e889e97b"
   integrity sha1-IDEU2CrSxe2ejgQRs5ModeiJ6Xs=
 
-resolve@^1.1.6, resolve@^1.10.0, resolve@^1.12.0, resolve@^1.13.1, resolve@^1.14.2, resolve@^1.15.0, resolve@^1.3.2, resolve@^1.5.0, resolve@^1.8.1:
-  version "1.15.0"
-  resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.15.0.tgz#1b7ca96073ebb52e741ffd799f6b39ea462c67f5"
-  integrity sha512-+hTmAldEGE80U2wJJDC1lebb5jWqvTYAfm3YZ1ckk1gBr0MnCqUKlwK1e+anaFljIl+F5tR5IoZcm4ZDA1zMQw==
+resolve@^1.1.6, resolve@^1.10.0, resolve@^1.12.0, resolve@^1.13.1, resolve@^1.14.2, resolve@^1.15.0, resolve@^1.15.1, resolve@^1.3.2, resolve@^1.5.0, resolve@^1.8.1:
+  version "1.15.1"
+  resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.15.1.tgz#27bdcdeffeaf2d6244b95bb0f9f4b4653451f3e8"
+  integrity sha512-84oo6ZTtoTUpjgNEr5SJyzQhzL72gaRodsSfyxC/AXRvwu0Yse9H8eF9IpGo7b8YetZhlI6v7ZQ6bKBFV/6S7w==
   dependencies:
     path-parse "^1.0.6"