feat(resolver): support package self-reference (#12682)

Author: SimenB

CHANGELOG.md

@@ -40,6 +40,7 @@
 - `[jest-reporters]` Add GitHub Actions reporter ([#11320](https://github.com/facebook/jest/pull/11320), [#12658](https://github.com/facebook/jest/pull/12658)
 - `[jest-reporters]` Pass `reporterContext` to custom reporter constructors as third argument ([#12657](https://github.com/facebook/jest/pull/12657))
 - `[jest-resolve]` [**BREAKING**] Add support for `package.json` `exports` ([#11961](https://github.com/facebook/jest/pull/11961), [#12373](https://github.com/facebook/jest/pull/12373))
+- `[jest-resolve]` Support package self-reference ([#12682](https://github.com/facebook/jest/pull/12682))
 - `[jest-resolve, jest-runtime]` Add support for `data:` URI import and mock ([#12392](https://github.com/facebook/jest/pull/12392))
 - `[jest-resolve, jest-runtime]` Add support for async resolver ([#11540](https://github.com/facebook/jest/pull/11540))
 - `[jest-runner]` Allow `setupFiles` module to export an async function ([#12042](https://github.com/facebook/jest/pull/12042))

packages/jest-resolve/src/__mocks__/self-ref/foo/file.js

@@ -0,0 +1,3 @@
+{
+  "name": "foo-no-exports"
+}

packages/jest-resolve/src/__mocks__/self-ref/foo/nested-with-no-exports/file.js

@@ -0,0 +1,4 @@
+{
+  "name": "foo-other-name",
+  "exports": "./file.js"
+}

packages/jest-resolve/src/__mocks__/self-ref/foo/nested-with-no-exports/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "foo",
+  "exports": "./file.js"
+}

packages/jest-resolve/src/__mocks__/self-ref/foo/nested-with-own-pkg/file.js

@@ -0,0 +1,3 @@
+{
+  "name": "self-ref"
+}

packages/jest-resolve/src/__mocks__/self-ref/foo/nested-with-own-pkg/package.json

@@ -37,6 +37,8 @@ beforeEach(() => {
   userResolver.mockClear();
   userResolverAsync.async.mockClear();
   mockResolveSync.mockClear();
+
+  Resolver.clearDefaultResolverCache();
 });
 
 describe('isCoreModule', () => {
@@ -251,6 +253,52 @@ describe('findNodeModule', () => {
       );
     });
   });
+
+  describe('self-reference', () => {
+    const selfRefRoot = path.resolve(__dirname, '../__mocks__/self-ref');
+
+    test('supports self-reference', () => {
+      const result = Resolver.findNodeModule('foo', {
+        basedir: path.resolve(selfRefRoot, './foo/index.js'),
+        conditions: [],
+      });
+
+      expect(result).toEqual(path.resolve(selfRefRoot, './foo/file.js'));
+    });
+
+    test('supports nested self-reference', () => {
+      const result = Resolver.findNodeModule('foo', {
+        basedir: path.resolve(selfRefRoot, './foo/nested/index.js'),
+        conditions: [],
+      });
+
+      expect(result).toEqual(path.resolve(selfRefRoot, './foo/file.js'));
+    });
+
+    test('fails if own pkg.json with different name', () => {
+      const result = Resolver.findNodeModule('foo', {
+        basedir: path.resolve(
+          selfRefRoot,
+          './foo/nested-with-own-pkg/index.js',
+        ),
+        conditions: [],
+      });
+
+      expect(result).toEqual(null);
+    });
+
+    test('fails if own pkg.json with no exports', () => {
+      const result = Resolver.findNodeModule('foo-no-exports', {
+        basedir: path.resolve(
+          selfRefRoot,
+          './foo/nested-with-no-exports/index.js',
+        ),
+        conditions: [],
+      });
+
+      expect(result).toEqual(null);
+    });
+  });
 });
 
 describe('findNodeModuleAsync', () => {

packages/jest-resolve/src/__mocks__/self-ref/foo/nested/file.js

@@ -14,6 +14,7 @@ import {
 } from 'resolve.exports';
 import {
   PkgJson,
+  findClosestPackageJson,
   isDirectory,
   isFile,
   readPackageCached,
@@ -36,7 +37,7 @@ interface ResolverOptions {
 }
 
 type UpstreamResolveOptionsWithConditions = UpstreamResolveOptions &
-  Pick<ResolverOptions, 'conditions'>;
+  Pick<ResolverOptions, 'basedir' | 'conditions'>;
 
 export type SyncResolver = (path: string, options: ResolverOptions) => string;
 export type AsyncResolver = (
@@ -112,6 +113,30 @@ function getPathInModule(
       moduleName = `${moduleName}/${segments.shift()}`;
     }
 
+    // self-reference
+    const closestPackageJson = findClosestPackageJson(options.basedir);
+    if (closestPackageJson) {
+      const pkg = readPackageCached(closestPackageJson);
+
+      if (pkg.name === moduleName && pkg.exports) {
+        const subpath = segments.join('/') || '.';
+
+        const resolved = resolveExports(
+          pkg,
+          subpath,
+          createResolveOptions(options.conditions),
+        );
+
+        if (!resolved) {
+          throw new Error(
+            '`exports` exists, but no results - this is a bug in Jest. Please report an issue',
+          );
+        }
+
+        return pathResolve(dirname(closestPackageJson), resolved);
+      }
+    }
+
     let packageJsonPath = '';
 
     try {
@@ -132,10 +157,13 @@ function getPathInModule(
           createResolveOptions(options.conditions),
         );
 
-        // TODO: should we throw if not?
-        if (resolved) {
-          return pathResolve(dirname(packageJsonPath), resolved);
+        if (!resolved) {
+          throw new Error(
+            '`exports` exists, but no results - this is a bug in Jest. Please report an issue',
+          );
         }
+
+        return pathResolve(dirname(packageJsonPath), resolved);
       }
     }
   }