test(compiler-cli): create initial "linked compile" compliance tests (#39617)

This commit adds bazel rules to test whether linking the golden partial
files for test cases produces the same output as a full compile of the
test case would.

PR Close #39617

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

@@ -0,0 +1,29 @@
+load("//tools:defaults.bzl", "jasmine_node_test", "ts_library")
+
+ts_library(
+    name = "test_lib",
+    testonly = True,
+    srcs = ["linked_compile_spec.ts"],
+    deps = [
+        "//packages/compiler-cli/linker/babel",
+        "//packages/compiler-cli/src/ngtsc/file_system",
+        "//packages/compiler-cli/test/compliance/test_helpers",
+        "@npm//@types/babel__core",
+    ],
+)
+
+jasmine_node_test(
+    name = "linked",
+    bootstrap = ["//tools/testing:node_no_angular_es5"],
+    data = [
+        "//packages/compiler-cli/test/compliance/test_cases",
+        "//packages/compiler-cli/test/ngtsc/fake_core:npm_package",
+    ],
+    shard_count = 2,
+    tags = [
+        "ivy-only",
+    ],
+    deps = [
+        ":test_lib",
+    ],
+)

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

@@ -0,0 +1,79 @@
+/**
+ * @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.io/license
+ */
+import {PluginObj, transformSync} from '@babel/core';
+
+import {createEs2015LinkerPlugin} from '../../../linker/babel';
+import {AbsoluteFsPath, FileSystem} from '../../../src/ngtsc/file_system';
+import {getBuildOutputDirectory} from '../test_helpers/compile_test';
+import {ComplianceTest} from '../test_helpers/get_compliance_tests';
+import {parseGoldenPartial} from '../test_helpers/golden_partials';
+import {runTests} from '../test_helpers/test_runner';
+
+runTests('partial compile + link', linkPartials);
+
+/**
+ * Link all the partials specified in the given `test`.
+ *
+ * @param fs The mock file-system to use for linking the partials.
+ * @param test The compliance test whose partials will be linked.
+ */
+function linkPartials(fs: FileSystem, test: ComplianceTest): void {
+  const builtDirectory = getBuildOutputDirectory(fs);
+  const linkerPlugin = createEs2015LinkerPlugin(test.angularCompilerOptions);
+  const goldenPartialPath = fs.resolve('/GOLDEN_PARTIAL.js');
+  if (!fs.exists(goldenPartialPath)) {
+    throw new Error(
+        'Golden partial does not exist for this test\n' +
+        'Try generating it by running:\n' +
+        `bazel run //packages/compiler-cli/test/compliance/test_cases:${
+            test.relativePath}.golden.update`);
+  }
+  const partialFile = fs.readFile(goldenPartialPath);
+  const partials = parseGoldenPartial(partialFile).filter(f => f.path.endsWith('.js'));
+  for (const partial of partials) {
+    const linkedSource =
+        applyLinker({fileName: partial.path, source: partial.content}, linkerPlugin);
+    safeWrite(fs, fs.resolve(builtDirectory, partial.path), linkedSource);
+  }
+}
+
+/**
+ * Run the file through the Babel linker plugin.
+ *
+ * It will ignore files that do not have a `.js` extension.
+ *
+ * @param file The file name and its source to be transformed using the linker.
+ * @param linkerPlugin The linker plugin to apply.
+ * @returns The file's source content, which has been transformed using the linker if necessary.
+ */
+function applyLinker(file: {fileName: string; source: string}, linkerPlugin: PluginObj): string {
+  if (!file.fileName.endsWith('.js')) {
+    return file.source;
+  }
+  const result = transformSync(file.source, {
+    filename: file.fileName,
+    plugins: [linkerPlugin],
+    parserOpts: {sourceType: 'unambiguous'},
+  });
+  if (result === null) {
+    throw fail('Babel transform did not have output');
+  }
+  if (result.code == null) {
+    throw fail('Babel transform result does not have any code');
+  }
+  return result.code;
+}
+
+/**
+ * Write the `content` to the `path` on the `fs` file-system, first ensuring that the containing
+ * directory exists.
+ */
+function safeWrite(fs: FileSystem, path: AbsoluteFsPath, content: string): void {
+  fs.ensureDir(fs.dirname(path));
+  fs.writeFile(path, content);
+}