build: re-enable linker compliance tests (#53571)

The linker compliance tests were disabled with a Babel update and
nobody realized for quite a while, via
https://github.com/angular/angular/pull/49914.

As we've came across this lost coverage, which also is quite
impactful as all libraries depend on linked output- I've took initiative
to debug the root cause as there was no follow-up.
https://github.com/angular/angular/issues/51647.

It turned out to be a highly complex issue that is non-trivial to fix,
but at least we should try to resurrect the significant portion of test
coverage by still running the linker tests- avoiding regressions, or
unexpected issues (like with defer being developed). We can work on
re-enabling and fixing source-maps separately.

Tracked via https://github.com/angular/angular/issues/51647.

PR Close #53571

packages/compiler-cli/test/compliance/linked/BUILD.bazel

@@ -24,10 +24,6 @@ jasmine_node_test(
         "//packages/compiler-cli/test/compliance/test_cases",
     ],
     shard_count = 2,
-    tags = [
-        # TODO: renable this test after debugging the issues related to babel updates
-        "manual",
-    ],
     deps = [
         ":test_lib",
     ],

packages/compiler-cli/test/compliance/linked/linked_compile_spec.ts

@@ -17,7 +17,10 @@ import {ComplianceTest} from '../test_helpers/get_compliance_tests';
 import {parseGoldenPartial} from '../test_helpers/golden_partials';
 import {runTests} from '../test_helpers/test_runner';
 
-runTests('linked compile', linkPartials);
+runTests('linked compile', linkPartials, {
+  // TODO: Remove when https://github.com/angular/angular/issues/51647 is resolved.
+  skipMappingChecks: true,
+});
 
 /**
  * Link all the partials specified in the given `test`.

packages/compiler-cli/test/compliance/test_helpers/check_expectations.ts

@@ -14,7 +14,7 @@ import {replaceMacros} from './expected_file_macros';
 import {verifyUniqueFunctions} from './function_checks';
 import {ExpectedFile, ExtraCheck} from './get_compliance_tests';
 import {verifyPlaceholdersIntegrity, verifyUniqueConsts} from './i18n_checks';
-import {checkMappings} from './sourcemap_helpers';
+import {stripAndCheckMappings} from './sourcemap_helpers';
 
 type ExtraCheckFunction = (generated: string, ...extraArgs: any[]) => boolean;
 const EXTRA_CHECK_FUNCTIONS: Record<string, ExtraCheckFunction> = {
@@ -31,10 +31,13 @@ const EXTRA_CHECK_FUNCTIONS: Record<string, ExtraCheckFunction> = {
  * @param testPath Path to the current test case (relative to the basePath).
  * @param failureMessage The message to display if the expectation fails.
  * @param expectedFiles The list of expected-generated pairs to compare.
+ * @param skipMappingCheck Whether to skip checking source mappings.
+ *   TODO: Remove this option. This only exists until we fix:
+ *         https://github.com/angular/angular/issues/51647.
  */
 export function checkExpectations(
     fs: ReadonlyFileSystem, testPath: string, failureMessage: string, expectedFiles: ExpectedFile[],
-    extraChecks: ExtraCheck[]): void {
+    extraChecks: ExtraCheck[], skipMappingCheck = false): void {
   const builtDirectory = getBuildOutputDirectory(fs);
   for (const expectedFile of expectedFiles) {
     const expectedPath = fs.resolve(getRootDirectory(fs), expectedFile.expected);
@@ -58,7 +61,9 @@ export function checkExpectations(
     const generated = fs.readFile(generatedPath);
     let expected = fs.readFile(expectedPath);
     expected = replaceMacros(expected);
-    expected = checkMappings(fs, generated, generatedPath, expected, expectedPath);
+    expected = stripAndCheckMappings(
+        fs, generated, generatedPath, expected, expectedPath,
+        /** skipMappingCheck */ !!skipMappingCheck);
 
     expectEmit(
         generated, expected,

packages/compiler-cli/test/compliance/test_helpers/sourcemap_helpers.ts

@@ -32,14 +32,19 @@ import {SourceFileLoader} from '../../../src/ngtsc/sourcemaps';
  * @param expectedSource The content of the expected source file, containing mapping information.
  * @returns The content of the expected source file, stripped of the mapping information.
  */
-export function checkMappings(
+export function stripAndCheckMappings(
     fs: ReadonlyFileSystem, generated: string, generatedPath: AbsoluteFsPath,
-    expectedSource: string, expectedPath: AbsoluteFsPath): string {
+    expectedSource: string, expectedPath: AbsoluteFsPath, skipMappingCheck: boolean): string {
   // Generate the candidate source maps.
   const actualMappings = getMappedSegments(fs, generatedPath, generated);
 
   const {expected, mappings} = extractMappings(fs, expectedSource);
 
+  // TODO: Remove when https://github.com/angular/angular/issues/51647 is fixed.
+  if (skipMappingCheck) {
+    return expected;
+  }
+
   const failures: string[] = [];
   for (const expectedMapping of mappings) {
     const failure = checkMapping(actualMappings, expectedMapping);

packages/compiler-cli/test/compliance/test_helpers/test_runner.ts

@@ -45,9 +45,7 @@ function getFilenameForLocalCompilation(fileName: string): string {
  */
 export function runTests(
     type: CompilationMode, compileFn: (fs: FileSystem, test: ComplianceTest) => CompileResult,
-    options = {
-      isLocalCompilation: false
-    }) {
+    options: {isLocalCompilation?: boolean, skipMappingChecks?: boolean} = {}) {
   describe(`compliance tests (${type})`, () => {
     for (const test of getAllComplianceTests()) {
       if (!test.compilationModeFilter.includes(type)) {
@@ -73,7 +71,7 @@ export function runTests(
           const fs = initMockTestFileSystem(test.realTestPath);
           const {errors} = compileFn(fs, test);
           for (const expectation of test.expectations) {
-            transformExpectation(expectation, options.isLocalCompilation);
+            transformExpectation(expectation, !!options.isLocalCompilation);
             if (expectation.expectedErrors.length > 0) {
               checkErrors(
                   test.relativePath, expectation.failureMessage, expectation.expectedErrors,
@@ -82,7 +80,7 @@ export function runTests(
               checkNoUnexpectedErrors(test.relativePath, errors);
               checkExpectations(
                   fs, test.relativePath, expectation.failureMessage, expectation.files,
-                  expectation.extraChecks);
+                  expectation.extraChecks, options.skipMappingChecks);
             }
           }
         });