Combine InMemoryAssetReader and InMemoryAssetWriter into InMemoryAssetReaderWriter (#3854)

* Refactor tests: create reader and writer inside `testBuilders`.

* Combine `InMemoryAssetReader` and `InMemoryAssetWriter` into `InMemoryAssetReaderWriter`.

Update tests so that reader and writer are backed by the same `InMemoryAssetReaderWriter`.

* Address review comments.

Author: davidmorgan

_test_common/lib/common.dart

@@ -14,8 +14,7 @@ export 'package:build_test/build_test.dart'
 export 'assets.dart';
 export 'builders.dart';
 export 'descriptors.dart';
-export 'in_memory_reader.dart';
-export 'in_memory_writer.dart';
+export 'in_memory_reader_writer.dart';
 export 'matchers.dart';
 export 'package_graphs.dart';
 export 'sdk.dart';

_test_common/lib/in_memory_reader.dart

@@ -10,10 +10,20 @@ import 'package:build_test/build_test.dart';
 import 'package:path/path.dart' as p;
 import 'package:watcher/watcher.dart';
 
-class InMemoryRunnerAssetWriter extends InMemoryAssetWriter
-    implements RunnerAssetWriter {
+class InMemoryRunnerAssetReaderWriter extends InMemoryAssetReaderWriter
+    implements RunnerAssetReader, RunnerAssetWriter {
+  final _onCanReadController = StreamController<AssetId>.broadcast();
+  Stream<AssetId> get onCanRead => _onCanReadController.stream;
   void Function(AssetId)? onDelete;
 
+  InMemoryRunnerAssetReaderWriter({super.sourceAssets, super.rootPackage});
+
+  @override
+  Future<bool> canRead(AssetId id) {
+    _onCanReadController.add(id);
+    return super.canRead(id);
+  }
+
   @override
   Future writeAsBytes(AssetId id, List<int> bytes) async {
     var type = assets.containsKey(id) ? ChangeType.MODIFY : ChangeType.ADD;

_test_common/lib/in_memory_writer.dart renamed to _test_common/lib/in_memory_reader_writer.dart

@@ -4,29 +4,26 @@
 
 import 'dart:async';
 
-// ignore: implementation_imports
-import 'package:build_runner_core/src/asset/reader.dart';
-// ignore: implementation_imports
-import 'package:build_runner_core/src/asset/writer.dart';
-// ignore: implementation_imports
-import 'package:build_runner_core/src/environment/build_environment.dart';
+import 'package:build_runner_core/build_runner_core.dart';
 import 'package:logging/logging.dart';
 
 import 'common.dart';
+import 'in_memory_reader_writer.dart';
 
 /// A [BuildEnvironment] for testing.
 ///
-/// Defaults to using an [InMemoryRunnerAssetReader] and
-/// [InMemoryRunnerAssetWriter].
+/// Defaults to an empty [InMemoryRunnerAssetReaderWriter].
 ///
 /// To handle prompts you must first set `nextPromptResponse`. Alternatively
 /// you can set `throwOnPrompt` to `true` to emulate a
 /// [NonInteractiveBuildException].
 class TestBuildEnvironment extends BuildEnvironment {
+  final InMemoryRunnerAssetReaderWriter _readerWriter;
+
   @override
-  final RunnerAssetReader reader;
+  RunnerAssetReader get reader => _readerWriter;
   @override
-  final RunnerAssetWriter writer;
+  RunnerAssetWriter get writer => _readerWriter;
 
   /// If true, this will throw a [NonInteractiveBuildException] for all calls to
   /// [prompt].
@@ -44,11 +41,9 @@ class TestBuildEnvironment extends BuildEnvironment {
   int? _nextPromptResponse;
 
   TestBuildEnvironment(
-      {RunnerAssetReader? reader,
-      RunnerAssetWriter? writer,
+      {InMemoryRunnerAssetReaderWriter? readerWriter,
       this.throwOnPrompt = false})
-      : reader = reader ?? InMemoryRunnerAssetReader(),
-        writer = writer ?? InMemoryRunnerAssetWriter();
+      : _readerWriter = readerWriter ?? InMemoryRunnerAssetReaderWriter();
 
   @override
   void onLog(LogRecord record) => logRecords.add(record);

_test_common/lib/test_environment.dart

@@ -11,8 +11,7 @@ import 'package:build_test/build_test.dart';
 import 'package:logging/logging.dart';
 import 'package:test/test.dart';
 
-import 'in_memory_reader.dart';
-import 'in_memory_writer.dart';
+import 'in_memory_reader_writer.dart';
 import 'package_graphs.dart';
 
 Future<void> wait(int milliseconds) =>
@@ -41,14 +40,13 @@ void _printOnFailure(LogRecord record) {
 /// For example `$$myapp|lib/utils.copy.dart` will check that the generated
 /// output was written to the build cache.
 ///
+/// [resumeFrom] reuses the `readerWriter` from a previous [BuildResult].
+///
 /// [packageGraph] supplies the root package into which the outputs are to be
 /// written.
 ///
 /// [status] optionally indicates the desired outcome.
 ///
-/// [writer] can optionally be provided to capture assets written by the
-/// builders (e.g. when [outputs] is not sufficient).
-///
 /// [logLevel] sets the builder log level and [onLog] can optionally capture
 /// build log messages.
 ///
@@ -67,15 +65,14 @@ void _printOnFailure(LogRecord record) {
 ///       });
 ///     }
 ///
-Future<BuildResult> testBuilders(
+Future<TestBuildersResult> testBuilders(
   List<BuilderApplication> builders,
   Map<String, /*String|List<int>*/ Object> inputs, {
+  TestBuildersResult? resumeFrom,
   Map<String, /*String|List<int>*/ Object>? outputs,
   PackageGraph? packageGraph,
   BuildStatus status = BuildStatus.success,
   Map<String, BuildConfig>? overrideBuildConfig,
-  InMemoryRunnerAssetReader? reader,
-  InMemoryRunnerAssetWriter? writer,
   Level? logLevel,
   // A better way to "silence" logging than setting logLevel to OFF.
   void Function(LogRecord record) onLog = _printOnFailure,
@@ -88,14 +85,16 @@ Future<BuildResult> testBuilders(
   Set<BuildFilter> buildFilters = const {},
   String? logPerformanceDir,
   String expectedGeneratedDir = 'generated',
+  void Function(AssetId id)? onDelete,
 }) async {
   packageGraph ??= buildPackageGraph({rootPackage('a'): []});
-  writer ??= InMemoryRunnerAssetWriter();
-  reader ??= InMemoryRunnerAssetReader.shareAssetCache(writer.assets,
-      rootPackage: packageGraph.root.name);
+  final readerWriter = resumeFrom == null
+      ? InMemoryRunnerAssetReaderWriter(rootPackage: packageGraph.root.name)
+      : resumeFrom.readerWriter;
+  readerWriter.onDelete = onDelete;
   var pkgConfigId =
       AssetId(packageGraph.root.name, '.dart_tool/package_config.json');
-  if (!await reader.canRead(pkgConfigId)) {
+  if (!await readerWriter.canRead(pkgConfigId)) {
     var packageConfig = {
       'configVersion': 2,
       'packages': [
@@ -108,21 +107,21 @@ Future<BuildResult> testBuilders(
           },
       ],
     };
-    await writer.writeAsString(pkgConfigId, jsonEncode(packageConfig));
+    await readerWriter.writeAsString(pkgConfigId, jsonEncode(packageConfig));
   }
 
   inputs.forEach((serializedId, contents) {
     var id = makeAssetId(serializedId);
     if (contents is String) {
-      reader!.cacheStringAsset(id, contents);
+      readerWriter.cacheStringAsset(id, contents);
     } else if (contents is List<int>) {
-      reader!.cacheBytesAsset(id, contents);
+      readerWriter.cacheBytesAsset(id, contents);
     }
   });
 
   builderConfigOverrides ??= const {};
   var environment = OverrideableEnvironment(IOEnvironment(packageGraph),
-      reader: reader, writer: writer, onLog: onLog);
+      reader: readerWriter, writer: readerWriter, onLog: onLog);
   var logSubscription =
       LogSubscription(environment, verbose: verbose, logLevel: logLevel);
   var options = await BuildOptions.create(logSubscription,
@@ -149,12 +148,13 @@ Future<BuildResult> testBuilders(
   if (checkBuildStatus) {
     checkBuild(result,
         outputs: outputs,
-        writer: writer,
+        writer: readerWriter,
         status: status,
         rootPackage: packageGraph.root.name,
         expectedGeneratedDir: expectedGeneratedDir);
   }
-  return result;
+
+  return TestBuildersResult(buildResult: result, readerWriter: readerWriter);
 }
 
 /// Translates expected outptus which start with `$$` to the build cache and
@@ -190,3 +190,10 @@ void checkBuild(BuildResult result,
         mapAssetIds: (id) => mapHidden(id, expectedGeneratedDir));
   }
 }
+
+class TestBuildersResult {
+  final BuildResult buildResult;
+  final InMemoryRunnerAssetReaderWriter readerWriter;
+
+  TestBuildersResult({required this.buildResult, required this.readerWriter});
+}

_test_common/lib/test_phases.dart

@@ -2,6 +2,7 @@
 
 - Add `package:build/src/internal.dart` for use by `build_resolvers`,
   `build_runner_core` and `build_test`.
+- Use `build_test` 3.0.0.
 
 ## 2.4.2
 

build/CHANGELOG.md

@@ -20,7 +20,7 @@ dependencies:
 
 dev_dependencies:
   build_resolvers: ^2.4.0
-  build_test: ^2.0.0
+  build_test: ^3.0.0-wip
   dart_flutter_team_lints: ^3.1.0
   test: ^1.16.0
 

build/pubspec.yaml

@@ -78,8 +78,7 @@ void main() {
     late InMemoryAssetReader reader;
 
     setUp(() {
-      writer = InMemoryAssetWriter();
-      reader = InMemoryAssetReader.shareAssetCache(writer.assets);
+      writer = reader = InMemoryAssetReaderWriter();
     });
 
     test('tracks outputs created by a builder', () async {

build/test/builder/build_step_impl_test.dart

@@ -29,8 +29,7 @@ void main() {
     });
     builder = TestBuilder(
         extraWork: (buildStep, __) => buildStep.fetchResource(resource));
-    writer = InMemoryAssetWriter();
-    reader = InMemoryAssetReader.shareAssetCache(writer.assets);
+    writer = reader = InMemoryAssetReaderWriter();
     addAssets(inputs, writer);
   });
 

build/test/generate/run_builder_test.dart

@@ -1,3 +1,7 @@
+## 5.0.12-wip
+
+- Use `build_test` 3.0.0.
+
 ## 5.0.11
 
 - Support 3.8.0 pre-release sdks.

build_modules/CHANGELOG.md

@@ -1,5 +1,5 @@
 name: build_modules
-version: 5.0.11
+version: 5.0.12-wip
 description: >-
   Builders to analyze and split Dart code into individually compilable modules
   based on imports.
@@ -32,7 +32,7 @@ dev_dependencies:
     path: test/fixtures/b
   # Used inside tests
   build_runner: ^2.0.0
-  build_test: ^2.0.0
+  build_test: ^3.0.0-wip
   json_serializable: ^6.0.0
   test: ^1.16.0
 

build_modules/pubspec.yaml

@@ -17,15 +17,13 @@ Future<void> testBuilderAndCollectAssets(
     void Function(LogRecord log)? onLog,
     void Function(AssetId, Iterable<AssetId>)?
         reportUnusedAssetsForInput}) async {
-  var writer = InMemoryAssetWriter();
   onLog ??= (log) => printOnFailure('${log.level}: ${log.message}');
-  await testBuilder(builder, assets,
+  final result = await testBuilder(builder, assets,
       generateFor: generateFor,
       outputs: outputs,
       onLog: onLog,
-      reportUnusedAssetsForInput: reportUnusedAssetsForInput,
-      writer: writer);
-  writer.assets.forEach((id, value) {
+      reportUnusedAssetsForInput: reportUnusedAssetsForInput);
+  result.readerWriter.assets.forEach((id, value) {
     assets['${id.package}|${id.path}'] = value;
   });
 }

build_modules/test/util.dart

@@ -3,6 +3,7 @@
 - Start using `package:build/src/internal.dart`.
 - Switch `BuildAssetUriResolver` dependency crawl to an iterative
   algorithm, preventing stack overflows.
+- Use `build_test` 3.0.0.
 
 ## 2.4.4
 

build_resolvers/CHANGELOG.md

@@ -24,7 +24,7 @@ dependencies:
   yaml: ^3.0.0
 
 dev_dependencies:
-  build_test: ^2.0.0
+  build_test: ^3.0.0-wip
   dart_flutter_team_lints: ^3.1.0
   test: ^1.16.0