allow optional direct injection of Config instance into DevFS (#144002)

In service of https://github.com/flutter/flutter/issues/143348

This will make testing of asset transformation hot reload behavior easier (specifically in that we can avoid having to write a test that looks like this: 5d02c27248/packages/flutter_tools/test/general.shard/build_system/targets/assets_test.dart (L167-L249)

packages/flutter_tools/lib/src/build_info.dart

@@ -800,6 +800,7 @@ HostPlatform getCurrentHostPlatform() {
 
 /// Returns the top-level build output directory.
 String getBuildDirectory([Config? config, FileSystem? fileSystem]) {
+  // TODO(andrewkolos): Prefer required parameters instead of falling back to globals.
   // TODO(johnmccutchan): Stop calling this function as part of setting
   // up command line argument processing.
   final Config localConfig = config ?? globals.config;
@@ -825,8 +826,9 @@ String getAotBuildDirectory() {
 }
 
 /// Returns the asset build output directory.
-String getAssetBuildDirectory() {
+String getAssetBuildDirectory([Config? config, FileSystem? fileSystem]) {
-  return globals.fs.path.join(getBuildDirectory(), 'flutter_assets');
+  return (fileSystem ?? globals.fs)
+    .path.join(getBuildDirectory(config, fileSystem), 'flutter_assets');
 }
 
 /// Returns the iOS build output directory.

packages/flutter_tools/lib/src/devfs.dart

@@ -8,6 +8,7 @@ import 'package:package_config/package_config.dart';
 import 'package:vm_service/vm_service.dart' as vm_service;
 
 import 'asset.dart';
+import 'base/config.dart';
 import 'base/context.dart';
 import 'base/file_system.dart';
 import 'base/io.dart';
@@ -456,6 +457,7 @@ class DevFS {
     HttpClient? httpClient,
     Duration? uploadRetryThrottle,
     StopwatchFactory stopwatchFactory = const StopwatchFactory(),
+    Config? config,
   }) : _vmService = serviceProtocol,
        _logger = logger,
        _fileSystem = fileSystem,
@@ -468,13 +470,15 @@ class DevFS {
         httpClient: httpClient ?? ((context.get<HttpClientFactory>() == null)
           ? HttpClient()
           : context.get<HttpClientFactory>()!())),
-       _stopwatchFactory = stopwatchFactory;
+       _stopwatchFactory = stopwatchFactory,
+       _config = config;
 
   final FlutterVmService _vmService;
   final _DevFSHttpWriter _httpWriter;
   final Logger _logger;
   final FileSystem _fileSystem;
   final StopwatchFactory _stopwatchFactory;
+  final Config? _config;
 
   final String fsName;
   final Directory? rootDirectory;
@@ -615,8 +619,8 @@ class DevFS {
 
       // The tool writes the assets into the AssetBundle working dir so that they
       // are in the same location in DevFS and the iOS simulator.
-      final String assetBuildDirPrefix = _asUriPath(getAssetBuildDirectory());
+      final String assetDirectory = getAssetBuildDirectory(_config, _fileSystem);
-      final String assetDirectory = getAssetBuildDirectory();
+      final String assetBuildDirPrefix = _asUriPath(assetDirectory);
       bundle.entries.forEach((String archivePath, AssetBundleEntry entry) {
         // If the content is backed by a real file, isModified will file stat and return true if
         // it was modified since the last time this was called.

packages/flutter_tools/test/general.shard/devfs_test.dart

@@ -11,6 +11,7 @@ import 'package:file/memory.dart';
 import 'package:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/artifacts.dart';
 import 'package:flutter_tools/src/asset.dart';
+import 'package:flutter_tools/src/base/config.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/logger.dart';
@@ -587,15 +588,8 @@ void main() {
   });
 
   group('Shader compilation', () {
-    late FileSystem fileSystem;
+    testWithoutContext('DevFS recompiles shaders', () async {
-    late ProcessManager processManager;
+      final MemoryFileSystem fileSystem = MemoryFileSystem.test();
-
-    setUp(() {
-      fileSystem = MemoryFileSystem.test();
-      processManager = FakeProcessManager.any();
-    });
-
-    testUsingContext('DevFS recompiles shaders', () async {
       final FakeVmServiceHost fakeVmServiceHost = FakeVmServiceHost(
         requests: <VmServiceExpectation>[createDevFSRequest],
         httpAddress: Uri.parse('http://localhost'),
@@ -609,6 +603,7 @@ void main() {
         logger: logger,
         osUtils: FakeOperatingSystemUtils(),
         httpClient: FakeHttpClient.any(),
+        config: Config.test(),
       );
 
       await devFS.create();
@@ -647,12 +642,10 @@ void main() {
       expect(report.success, true);
       expect(devFS.shaderPathsToEvict, <String>{'foo.frag'});
       expect(devFS.assetPathsToEvict, <String>{'not.frag'});
-    }, overrides: <Type, Generator>{
-      FileSystem: () => fileSystem,
-      ProcessManager: () => processManager,
     });
 
-    testUsingContext('DevFS tracks when FontManifest is updated', () async {
+    testWithoutContext('DevFS tracks when FontManifest is updated', () async {
+      final MemoryFileSystem fileSystem = MemoryFileSystem.test();
       final FakeVmServiceHost fakeVmServiceHost = FakeVmServiceHost(
         requests: <VmServiceExpectation>[createDevFSRequest],
         httpAddress: Uri.parse('http://localhost'),
@@ -666,6 +659,7 @@ void main() {
         logger: logger,
         osUtils: FakeOperatingSystemUtils(),
         httpClient: FakeHttpClient.any(),
+        config: Config.test(),
       );
 
       await devFS.create();
@@ -702,9 +696,6 @@ void main() {
       expect(devFS.shaderPathsToEvict, <String>{});
       expect(devFS.assetPathsToEvict, <String>{'FontManifest.json'});
       expect(devFS.didUpdateFontManifest, true);
-    }, overrides: <Type, Generator>{
-      FileSystem: () => fileSystem,
-      ProcessManager: () => processManager,
     });
   });
 }