feat(bazel): always fake home-system directories in integration tests

This allows us to remove all the Yarn tricks for locally-installed
NPM package archives (those were cached accidentally -- when run locally
without a sandbox for example).

Also this makes all integration tests more hermetic.

bazel/integration/test_runner/runner.ts

@@ -9,6 +9,7 @@
 import * as fs from 'fs';
 import * as path from 'path';
 import * as tmp from 'tmp';
+import * as os from 'os';
 
 import {
   BazelExpandedValue,
@@ -35,6 +36,9 @@ import {debug} from './debug';
 /** Error class that is used when an integration command fails.  */
 class IntegrationTestCommandError extends Error {}
 
+/** Type describing an environment configuration that can be passed to the runner. */
+type EnvironmentConfig = Record<string, BazelExpandedValue>;
+
 /**
  * Test runner that takes a set of files within a Bazel package and copies the files
  * to a temporary directory where it then executes a list of specified commands.
@@ -44,15 +48,19 @@ class IntegrationTestCommandError extends Error {}
  * test runner will patch the top-level `package.json` of the test Bazel package for that.
  */
 export class TestRunner {
+  private readonly environment: EnvironmentConfig;
+
   constructor(
     private readonly testFiles: BazelFileInfo[],
     private readonly testPackage: string,
     private readonly testPackageRelativeWorkingDir: string,
     private readonly toolMappings: Record<string, BazelFileInfo>,
     private readonly npmPackageMappings: Record<string, BazelFileInfo>,
     private readonly commands: [[binary: BazelExpandedValue, ...args: string[]]],
-    private readonly environment: Record<string, BazelExpandedValue>,
-  ) {}
+    environment: EnvironmentConfig,
+  ) {
+    this.environment = this._assignDefaultEnvironmentVariables(environment);
+  }
 
   async run() {
     const testTmpDir = await this._getTestTmpDirectoryPath();
@@ -262,4 +270,27 @@ export class TestRunner {
     }
     return mappings;
   }
+
+  /**
+   * Assigns the default environment environments.
+   *
+   * We intend to always fake the system home-related directory environment variables
+   * to temporary directories. This helps as integration tests (even within the Bazel sandbox)
+   * have read access to the system home directory and attempt to write to it.
+   */
+  private _assignDefaultEnvironmentVariables(baseEnv: EnvironmentConfig): EnvironmentConfig {
+    const defaults: EnvironmentConfig = {
+      'HOME': {value: ENVIRONMENT_TMP_PLACEHOLDER, containsExpansion: false},
+    };
+
+    // Support windows-specific system variables. We don't want to always assign these as
+    // it would result in unnecessary directories being created all the time.
+    if (os.platform() === 'win32') {
+      defaults.USERPROFILE = {value: ENVIRONMENT_TMP_PLACEHOLDER, containsExpansion: false};
+      defaults.APPDATA = {value: ENVIRONMENT_TMP_PLACEHOLDER, containsExpansion: false};
+      defaults.LOCALAPPDATA = {value: ENVIRONMENT_TMP_PLACEHOLDER, containsExpansion: false};
+    }
+
+    return {...defaults, ...baseEnv};
+  }
 }

bazel/integration/tests/angular-cli/BUILD.bazel

@@ -14,8 +14,6 @@ integration_test(
         "//bazel/browsers/chromium",
     ],
     environment = {
-        # Ensure Yarn does not try to access the shared system cache (even within sandboxing)
-        "HOME": "<TMP>",
         "CHROMEDRIVER_SKIP_DOWNLOAD": "true",
         "CHROMEDRIVER_PATH": "$(CHROMEDRIVER)",
         "CHROME_BIN": "$(CHROMIUM)",

bazel/integration/tests/custom_env_variables/test.js

@@ -20,6 +20,11 @@ if (process.env.MANUAL_ROOT_PATH !== '../npm/node_modules/semver/package.json')
   process.exit(1);
 }
 
+if (!process.env.HOME.includes('.tmp-env-')) {
+  console.error('Expected `HOME` to point to a temporary environment directory.');
+  process.exit(1);
+}
+
 const bazeliskHome = process.env.BAZELISK_HOME;
 const bazeliskHome_2 = process.env.BAZELISK_HOME_2;
 

bazel/integration/tests/nested_bazel_workspaces/BUILD.bazel

@@ -10,12 +10,6 @@ integration_test(
         "yarn",
         "yarn test",
     ],
-    environment = {
-        # Setup a HOME directory so that Bazelisk can work, both Linux/macOS and Windows variants
-        # are configured to provide a fake home directory so that Bazelisk can download Bazel.
-        "HOME": "<TMP>",
-        "LOCALAPPDATA": "<TMP>",
-    },
     tags = [
         # This test relies on `yarn` so there needs to be internet access.
         "requires-network",

bazel/integration/tests/package_mappings/BUILD.bazel

@@ -7,15 +7,17 @@ integration_test(
         "test.mjs",
     ],
     commands = [
-        # Note: We use a cache folder within the integration test as otherwise
-        # the NPM package mapped archive would be cached in the system.
-        # See: https://github.com/yarnpkg/yarn/issues/2165.
-        "yarn install --cache-folder .yarn_cache_folder/",
+        "yarn",
         "node ./test.mjs",
     ],
     npm_packages = {
         "//bazel/integration/tests/package_mappings/fake_pkg_srcs:archive": "fake_pkg",
     },
+    tags = [
+        # We want to run a basic integration test on Windows to ensure the integration
+        # test rule works properly for Windows contributors.
+        "windows",
+    ],
     tool_mappings = {
         "//:yarn_classic_vendored": "yarn",
         "@nodejs_toolchains//:resolved_toolchain": "node",

bazel/integration/tests/playwright_chromium/BUILD.bazel

@@ -12,8 +12,6 @@ integration_test(
         "//bazel/browsers/chromium",
     ],
     environment = {
-        # Ensure Yarn does not try to access the shared system cache (even within sandboxing)
-        "HOME": "<TMP>",
         "CHROME_BIN": "$(CHROMIUM)",
     },
     tags = [