feat: support subpath imports

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 
+- `[jest-resolve]` Support subpath imports ([#13705](https://github.com/facebook/jest/pull/13705))
 - `[jest-runtime]` Add `jest.isolateModulesAsync` for scoped module initialization of asynchronous functions ([#13680](https://github.com/facebook/jest/pull/13680))
 - `[jest-test-result]` Added `skipped` and `focused` status to `FormattedTestResult` ([#13700](https://github.com/facebook/jest/pull/13700))
 

e2e/__tests__/__snapshots__/moduleNameMapper.test.ts.snap

@@ -41,7 +41,7 @@ exports[`moduleNameMapper wrong array configuration 1`] = `
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:758:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:760:17)
       at Object.require (index.js:10:1)
       at Object.require (__tests__/index.js:10:20)"
 `;
@@ -71,7 +71,7 @@ exports[`moduleNameMapper wrong configuration 1`] = `
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:758:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:760:17)
       at Object.require (index.js:10:1)
       at Object.require (__tests__/index.js:10:20)"
 `;

e2e/__tests__/__snapshots__/requireMissingExt.test.ts.snap

@@ -26,7 +26,7 @@ exports[`shows a proper error from deep requires 1`] = `
       12 | test('dummy', () => {
       13 |   expect(1).toBe(1);
 
-      at Resolver._throwModNotFoundError (../../packages/jest-resolve/build/resolver.js:425:11)
+      at Resolver._throwModNotFoundError (../../packages/jest-resolve/build/resolver.js:427:11)
       at Object.<anonymous> (node_modules/discord.js/src/index.js:21:12)
       at Object.require (__tests__/test.js:10:1)"
 `;

e2e/__tests__/__snapshots__/resolveNoFileExtensions.test.ts.snap

@@ -37,7 +37,7 @@ exports[`show error message with matching files 1`] = `
         |                  ^
       9 |
 
-      at Resolver._throwModNotFoundError (../../packages/jest-resolve/build/resolver.js:425:11)
+      at Resolver._throwModNotFoundError (../../packages/jest-resolve/build/resolver.js:427:11)
       at Object.require (index.js:8:18)
       at Object.require (__tests__/test.js:8:11)"
 `;

packages/jest-resolve/package.json

@@ -17,6 +17,7 @@
     "./package.json": "./package.json"
   },
   "dependencies": {
+    "@okikio/resolve.imports": "^1.0.0",
     "chalk": "^4.0.0",
     "graceful-fs": "^4.2.9",
     "jest-haste-map": "workspace:^",

packages/jest-resolve/src/__mocks__/imports/foo-import/package.json

@@ -0,0 +1,9 @@
+{
+  "name": "foo-import",
+  "imports": {
+    "#nested": {
+      "require": "./internal.cjs",
+      "default": "external-foo"
+    }
+  }
+}

packages/jest-resolve/src/__mocks__/imports/package.json

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

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

@@ -316,6 +316,44 @@ describe('findNodeModule', () => {
       expect(result).toBeNull();
     });
   });
+
+  describe('imports', () => {
+    const importsRoot = path.resolve(__dirname, '../__mocks__/imports');
+
+    test('supports internal reference', () => {
+      const result = Resolver.findNodeModule('#nested', {
+        basedir: path.resolve(importsRoot, './foo-import/index.cjs'),
+        conditions: ['require'],
+      });
+
+      expect(result).toEqual(
+        path.resolve(importsRoot, './foo-import/internal.cjs'),
+      );
+    });
+
+    test('supports external reference', () => {
+      const result = Resolver.findNodeModule('#nested', {
+        basedir: path.resolve(importsRoot, './foo-import/index.js'),
+        conditions: [],
+      });
+
+      expect(result).toEqual(
+        path.resolve(
+          importsRoot,
+          './foo-import/node_modules/external-foo/main.js',
+        ),
+      );
+    });
+
+    test('fails for non-existent mapping', () => {
+      expect(() => {
+        Resolver.findNodeModule('#something-else', {
+          basedir: path.resolve(importsRoot, './foo-import/index.js'),
+          conditions: [],
+        });
+      }).toThrow('Missing "#something-else" import in "foo-import" package');
+    });
+  });
 });
 
 describe('findNodeModuleAsync', () => {

packages/jest-resolve/src/defaultResolver.ts

@@ -6,6 +6,7 @@
  */
 
 import {dirname, isAbsolute, resolve as pathResolve} from 'path';
+import {resolve as resolveImports} from '@okikio/resolve.imports';
 import pnpResolver from 'jest-pnp-resolver';
 import {SyncOpts as UpstreamResolveOptions, sync as resolveSync} from 'resolve';
 import {
@@ -83,7 +84,7 @@ export type ResolverOptions = {
 };
 
 type UpstreamResolveOptionsWithConditions = UpstreamResolveOptions &
-  Pick<ResolverOptions, 'basedir' | 'conditions'>;
+  ResolverOptions;
 
 export type SyncResolver = (path: string, options: ResolverOptions) => string;
 export type AsyncResolver = (
@@ -136,12 +137,42 @@ function getPathInModule(
     return path;
   }
 
+  if (path.startsWith('#')) {
+    const closestPackageJson = findClosestPackageJson(options.basedir);
+
+    if (!closestPackageJson) {
+      throw new Error(
+        `Jest: unable to locate closest package.json from ${options.basedir} when resolving import "${path}"`,
+      );
+    }
+
+    const pkg = readPackageCached(closestPackageJson);
+
+    const resolved = resolveImports(
+      pkg,
+      path,
+      createResolveOptions(options.conditions),
+    );
+
+    if (!resolved) {
+      throw new Error(
+        '`imports` exists, but no results - this is a bug in Jest. Please report an issue',
+      );
+    }
+
+    if (resolved.startsWith('.')) {
+      return pathResolve(dirname(closestPackageJson), resolved);
+    }
+
+    // this is an external module, re-resolve it
+    return defaultResolver(resolved, options);
+  }
+
   const segments = path.split('/');
 
   let moduleName = segments.shift();
 
   if (moduleName) {
-    // TODO: handle `#` here: https://github.com/facebook/jest/issues/12270
     if (moduleName.startsWith('@')) {
       moduleName = `${moduleName}/${segments.shift()}`;
     }
@@ -213,6 +244,6 @@ function createResolveOptions(
       {browser: false, require: true};
 }
 
-// if it's a relative import or an absolute path, exports are ignored
+// if it's a relative import or an absolute path, imports/exports are ignored
 const shouldIgnoreRequestForExports = (path: string) =>
   path.startsWith('.') || isAbsolute(path);

packages/jest-resolve/src/resolver.ts

@@ -131,7 +131,8 @@ export default class Resolver {
         rootDir: options.rootDir,
       });
     } catch (e) {
-      if (options.throwIfNotFound) {
+      // we always wanna throw if it's an internal import
+      if (options.throwIfNotFound || path.startsWith('#')) {
         throw e;
       }
     }
@@ -174,7 +175,8 @@ export default class Resolver {
       });
       return result;
     } catch (e: unknown) {
-      if (options.throwIfNotFound) {
+      // we always wanna throw if it's an internal import
+      if (options.throwIfNotFound || path.startsWith('#')) {
         throw e;
       }
     }

yarn.lock

@@ -3757,6 +3757,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@okikio/resolve.imports@npm:^1.0.0":
+  version: 1.0.0
+  resolution: "@okikio/resolve.imports@npm:1.0.0"
+  checksum: a06d347731b3c47e79125d346dd0172fda3cf20d138249f4ed23c5cc60b32f668f9bbab49698fc061ef5782d236622ff4cd0ce2b2520550273e863f55b687350
+  languageName: node
+  linkType: hard
+
 "@pkgr/utils@npm:^2.3.1":
   version: 2.3.1
   resolution: "@pkgr/utils@npm:2.3.1"
@@ -12918,6 +12925,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "jest-resolve@workspace:packages/jest-resolve"
   dependencies:
+    "@okikio/resolve.imports": ^1.0.0
     "@tsd/typescript": ^4.9.0
     "@types/graceful-fs": ^4.1.3
     "@types/pnpapi": ^0.0.2