fix(@angular/build): add filename truncation to test discovery

packages/angular/build/src/builders/unit-test/test-discovery.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
+import { createHash } from 'node:crypto';
 import { type PathLike, constants, promises as fs } from 'node:fs';
 import os from 'node:os';
 import { basename, dirname, extname, isAbsolute, join, relative } from 'node:path';
@@ -18,6 +19,9 @@ import { toPosixPath } from '../../utils/path';
  */
 const TEST_FILE_INFIXES = ['.spec', '.test'];
 
+/** Maximum length for a generated test entrypoint name. */
+const MAX_FILENAME_LENGTH = 128;
+
 /**
  * Finds all test files in the project. This function implements a special handling
  * for static paths (non-globs) to improve developer experience. For example, if a
@@ -120,7 +124,7 @@ export function getTestEntrypoints(
  * @param removeTestExtension Whether to remove the test file infix and extension from the result.
  * @returns A dash-cased name derived from the relative path of the test file.
  */
-function generateNameFromPath(
+export function generateNameFromPath(
   testFile: string,
   roots: string[],
   removeTestExtension: boolean,
@@ -155,7 +159,29 @@ function generateNameFromPath(
     result += char === '/' || char === '\\' ? '-' : char;
   }
 
-  return result;
+  return truncateName(result, relativePath);
+}
+
+/**
+ * Truncates a generated name if it exceeds the maximum allowed filename length.
+ * If truncation occurs, the name will be shortened by replacing a middle segment
+ * with an 8-character SHA256 hash of the original full path to maintain uniqueness.
+ *
+ * @param name The generated name to potentially truncate.
+ * @param originalPath The original full path from which the name was derived. Used for hashing.
+ * @returns The original name if within limits, or a truncated name with a hash.
+ */
+function truncateName(name: string, originalPath: string): string {
+  if (name.length <= MAX_FILENAME_LENGTH) {
+    return name;
+  }
+
+  const hash = createHash('sha256').update(originalPath).digest('hex').substring(0, 8);
+  const availableLength = MAX_FILENAME_LENGTH - hash.length - 2; // 2 for '-' separators
+  const prefixLength = Math.floor(availableLength / 2);
+  const suffixLength = availableLength - prefixLength;
+
+  return `${name.substring(0, prefixLength)}-${hash}-${name.substring(name.length - suffixLength)}`;
 }
 
 /**

packages/angular/build/src/builders/unit-test/test-discovery_spec.ts

@@ -0,0 +1,91 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import { generateNameFromPath } from './test-discovery';
+
+describe('generateNameFromPath', () => {
+  const roots = ['/project/src/', '/project/'];
+
+  it('should generate a dash-cased name from a simple path', () => {
+    const testFile = '/project/src/app/components/my-component.spec.ts';
+    const result = generateNameFromPath(testFile, roots, true);
+    expect(result).toBe('app-components-my-component');
+  });
+
+  it('should handle Windows-style paths', () => {
+    const testFile = 'C:\\project\\src\\app\\components\\my-component.spec.ts';
+    const result = generateNameFromPath(testFile, ['C:\\project\\src\\'], true);
+    expect(result).toBe('app-components-my-component');
+  });
+
+  it('should remove test extensions when removeTestExtension is true', () => {
+    const testFile = '/project/src/app/utils/helpers.test.ts';
+    const result = generateNameFromPath(testFile, roots, true);
+    expect(result).toBe('app-utils-helpers');
+  });
+
+  it('should not remove test extensions when removeTestExtension is false', () => {
+    const testFile = '/project/src/app/utils/helpers.test.ts';
+    const result = generateNameFromPath(testFile, roots, false);
+    expect(result).toBe('app-utils-helpers.test');
+  });
+
+  it('should handle paths with leading dots and slashes', () => {
+    const testFile = '/project/src/./app/services/api.service.spec.ts';
+    const result = generateNameFromPath(testFile, roots, true);
+    expect(result).toBe('app-services-api.service');
+  });
+
+  it('should return the basename if no root matches', () => {
+    const testFile = '/unrelated/path/to/some/file.spec.ts';
+    const result = generateNameFromPath(testFile, roots, true);
+    expect(result).toBe('file');
+  });
+
+  it('should truncate a long file name', () => {
+    const longPath =
+      'a/very/long/path/that/definitely/exceeds/the/maximum/allowed/length/for/a/filename/in/order/to/trigger/the/truncation/logic/in/the/function.spec.ts'; // eslint-disable-line max-len
+    const testFile = `/project/src/${longPath}`;
+    const result = generateNameFromPath(testFile, roots, true);
+
+    expect(result.length).toBeLessThanOrEqual(128);
+    expect(result).toBe(
+      'a-very-long-path-that-definitely-exceeds-the-maximum-allowe-9cf40291-me-in-order-to-trigger-the-truncation-logic-in-the-function',
+    ); // eslint-disable-line max-len
+  });
+
+  it('should generate different hashes for different paths with similar truncated names', () => {
+    const longPath1 =
+      'a/very/long/path/that/definitely/exceeds/the/maximum/allowed/length/for/a/filename/in/order/to/trigger/the/truncation/logic/variant-a.spec.ts'; // eslint-disable-line max-len
+    const longPath2 =
+      'a/very/long/path/that/definitely/exceeds/the/maximum/allowed/length/for/a/filename/in/order/to/trigger/the/truncation/logic/variant-b.spec.ts'; // eslint-disable-line max-len
+
+    const testFile1 = `/project/src/${longPath1}`;
+    const testFile2 = `/project/src/${longPath2}`;
+
+    const result1 = generateNameFromPath(testFile1, roots, true);
+    const result2 = generateNameFromPath(testFile2, roots, true);
+
+    expect(result1).not.toBe(result2);
+    // The hash is always 8 characters long and is surrounded by hyphens.
+    const hashRegex = /-[a-f0-9]{8}-/;
+    const hash1 = result1.match(hashRegex)?.[0];
+    const hash2 = result2.match(hashRegex)?.[0];
+
+    expect(hash1).toBeDefined();
+    expect(hash2).toBeDefined();
+    expect(hash1).not.toBe(hash2);
+  });
+
+  it('should not truncate a filename that is exactly the max length', () => {
+    const name = 'a'.repeat(128);
+    const testFile = `/project/src/${name}.spec.ts`;
+    const result = generateNameFromPath(testFile, roots, true);
+    expect(result).toBe(name);
+  });
+});