fix(resolver): allow importing packages with non-index main script (#26692)

Regressed in https://github.com/microsoft/playwright/pull/23254.

Fixes #26650.

packages/playwright-test/src/util.ts

@@ -342,8 +342,13 @@ export function resolveImportSpecifierExtension(resolved: string): string | unde
     }
     break;  // Do not try '' when a more specific extesion like '.jsx' matched.
   }
-  // try directory imports last
+
   if (dirExists(resolved)) {
+    // If we import a package, let Node.js figure out the correct import based on package.json.
+    if (fileExists(path.join(resolved, 'package.json')))
+      return resolved;
+
+    // Otherwise, try to find a corresponding index file.
     const dirImport = path.join(resolved, 'index');
     return resolveImportSpecifierExtension(dirImport);
   }

tests/playwright-test/resolver.spec.ts

@@ -505,3 +505,40 @@ test('should support extends in tsconfig.json', async ({ runInlineTest }) => {
   expect(result.passed).toBe(1);
   expect(result.exitCode).toBe(0);
 });
+
+test('should import packages with non-index main script through path resolver', async ({ runInlineTest }) => {
+  const result = await runInlineTest({
+    'app/pkg/main.ts': `
+      export const foo = 42;
+    `,
+    'app/pkg/package.json': `
+      { "main": "main.ts" }
+    `,
+    'package.json': `
+      { "name": "example-project" }
+    `,
+    'playwright.config.ts': `
+      export default {};
+    `,
+    'tsconfig.json': `{
+      "compilerOptions": {
+        "baseUrl": ".",
+        "paths": {
+          "app/*": ["app/*"],
+        },
+      },
+    }`,
+    'example.spec.ts': `
+      import { foo } from 'app/pkg';
+      import { test, expect } from '@playwright/test';
+      test('test', ({}) => {
+        console.log('foo=' + foo);
+      });
+    `,
+  });
+
+  expect(result.exitCode).toBe(0);
+  expect(result.passed).toBe(1);
+  expect(result.output).not.toContain(`find module`);
+  expect(result.output).toContain(`foo=42`);
+});