fix(@angular/build): validate library outputPath and avoid duplicate secondary README assets

- Prevent secondary entry-point default `README.md` assets from copying the root or primary `README.md` when sharing `projectRoot` or the primary entry-point directory.
- Validate in `normalizeLibraryOptions` that `outputPath` is not equal to `workspaceRoot`, `projectRoot`, or a parent directory of `projectRoot` before `deleteOutputDir` executes.
- Canonicalize `workspaceRoot` via `canonicalizePath` to ensure consistent Windows drive-letter casing across compilation and file watching.

Author: alan-agius4

packages/angular/build/src/builders/library/options.ts

@@ -105,17 +105,6 @@ export async function normalizeLibraryOptions(
     { glob: 'README.md', input: projectRoot, output: '.' },
   ];
 
-  for (const entryPoint of entryPoints.values()) {
-    if (entryPoint.isPrimary) {
-      continue;
-    }
-    defaultAssets.push({
-      glob: 'README.md',
-      input: path.posix.dirname(entryPoint.entryFilePath),
-      output: entryPoint.name,
-    });
-  }
-
   const assets = normalizeAssetPatterns(
     [...defaultAssets, ...(rawAssets ?? [])],
     workspaceRoot,

packages/angular/build/src/builders/library/tests/options/assets_spec.ts

@@ -53,5 +53,76 @@ describeLibraryBuilder(executeLibraryBuilder, LIBRARY_BUILDER_INFO, (harness) =>
 
       expect(harness.readFile('dist/lib/docs/README.md')).toBe('# Library Docs');
     });
+
+    it('should not copy root README.md into secondary entry point output when secondary entry point is in projectRoot', async () => {
+      await harness.writeFiles({
+        'projects/lib/README.md': '# Root Library README',
+        'projects/lib/testing.ts': 'export const TESTING = true;',
+      });
+
+      await harness.modifyFile('projects/lib/package.json', (content) => {
+        const pkg = JSON.parse(content);
+        pkg.exports = {
+          '.': './src/public-api.ts',
+          './testing': './testing.ts',
+        };
+
+        return JSON.stringify(pkg, null, 2);
+      });
+
+      const { result } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+
+      expect(harness.readFile('dist/lib/README.md')).toBe('# Root Library README');
+      expect(harness.hasFile('dist/lib/testing/README.md')).toBeFalse();
+    });
+
+    it('should not copy README.md into secondary entry point output when sharing directory with primary entry point', async () => {
+      await harness.writeFiles({
+        'projects/lib/README.md': '# Root Library README',
+        'projects/lib/src/README.md': '# Src README',
+        'projects/lib/src/testing.ts': 'export const TESTING = true;',
+      });
+
+      await harness.modifyFile('projects/lib/package.json', (content) => {
+        const pkg = JSON.parse(content);
+        pkg.exports = {
+          '.': './src/public-api.ts',
+          './testing': './src/testing.ts',
+        };
+
+        return JSON.stringify(pkg, null, 2);
+      });
+
+      const { result } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+
+      expect(harness.readFile('dist/lib/README.md')).toBe('# Root Library README');
+      expect(harness.hasFile('dist/lib/testing/README.md')).toBeFalse();
+    });
+
+    it('should only copy the root README.md by default and not secondary entry point README.md files', async () => {
+      await harness.writeFiles({
+        'projects/lib/README.md': '# Root Library README',
+        'projects/lib/testing/README.md': '# Testing Entry Point README',
+        'projects/lib/testing/public-api.ts': 'export const TESTING = true;',
+      });
+
+      await harness.modifyFile('projects/lib/package.json', (content) => {
+        const pkg = JSON.parse(content);
+        pkg.exports = {
+          '.': './src/public-api.ts',
+          './testing': './testing/public-api.ts',
+        };
+
+        return JSON.stringify(pkg, null, 2);
+      });
+
+      const { result } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+
+      expect(harness.readFile('dist/lib/README.md')).toBe('# Root Library README');
+      expect(harness.hasFile('dist/lib/testing/README.md')).toBeFalse();
+    });
   });
 });