Improve build_test testBuilders package setup. (#4069)

Author: davidmorgan

build_test/CHANGELOG.md

@@ -1,3 +1,9 @@
+## 3.1.2
+
+- Fixes when passing a `readerWriter` to `testBuilders`: don't count initial
+  assets as outputs; do set up packages for initial assets; only apply builders
+  to packages mentioned in `sourceAssets`.
+
 ## 3.1.1
 
 - Bug fix: stop parsing `testBuilder` asset paths as globs.

build_test/lib/src/in_memory_reader_writer.dart

@@ -191,7 +191,8 @@ class _ReaderWriterTestingImpl implements ReaderWriterTesting {
         Glob('**'),
         package: package.name,
       )) {
-        await _readerWriter.writeAsBytes(id, await reader.readAsBytes(id));
+        // Write via `testing` so it's not tracked as a builder output.
+        _readerWriter.testing.writeBytes(id, await reader.readAsBytes(id));
       }
     }
   }

build_test/lib/src/test_builder.dart

@@ -237,7 +237,16 @@ Future<TestBuilderResult> testBuilders(
     for (var descriptor in sourceAssets.keys) makeAssetId(descriptor),
   };
 
-  var allPackages = {for (var id in inputIds) id.package};
+  // Differentiate input packages and all packages. Builders run on input
+  // packages; they can read/resolve all packages. Additional packages are
+  // supplied by passing a `readerWriter`.
+  var inputPackages = {for (var id in inputIds) id.package};
+  final allPackages = inputPackages.toSet();
+  if (readerWriter != null) {
+    for (final asset in readerWriter.testing.assets) {
+      allPackages.add(asset.package);
+    }
+  }
   rootPackage ??= allPackages.first;
 
   readerWriter ??= TestReaderWriter(rootPackage: rootPackage);
@@ -302,7 +311,7 @@ Future<TestBuilderResult> testBuilders(
         // picking up `lib/**` but not all files in the package root.
         testingBuilderConfig
             ? {
-              for (final package in allPackages)
+              for (final package in inputPackages)
                 package: BuildConfig.fromMap(package, [], {
                   'targets': {
                     package: {
@@ -334,7 +343,7 @@ Future<TestBuilderResult> testBuilders(
       apply(
         builderName(builder),
         [(_) => builder],
-        (package) => package.name != r'$sdk',
+        (p) => inputPackages.contains(p.name),
         isOptional: optionalBuilders.contains(builder),
         hideOutput: !visibleOutputBuilders.contains(builder),
       ),

build_test/pubspec.yaml

@@ -1,6 +1,6 @@
 name: build_test
 description: Utilities for writing unit tests of Builders.
-version: 3.1.1
+version: 3.1.2
 repository: https://github.com/dart-lang/build/tree/master/build_test
 resolution: workspace
 

build_test/test/test_builder_test.dart

@@ -7,6 +7,7 @@ import 'dart:async';
 import 'package:build/build.dart';
 import 'package:build_test/build_test.dart';
 import 'package:glob/glob.dart';
+import 'package:logging/logging.dart';
 import 'package:package_config/package_config.dart';
 import 'package:test/test.dart';
 
@@ -368,6 +369,43 @@ Future<void> main() async {
       outputs: {'a|[.out': 'input'},
     );
   });
+
+  test('resolve isolate source', () async {
+    final readerWriter = TestReaderWriter(rootPackage: 'a');
+    await readerWriter.testing.loadIsolateSources();
+    final logs = <String>[];
+    await testBuilders(
+      [
+        TestBuilder(
+          build: (buildStep, _) async {
+            await buildStep.resolver.libraryFor(
+              AssetId('glob', 'lib/glob.dart'),
+            );
+            await buildStep.writeAsString(
+              buildStep.inputId.changeExtension('.g.dart'),
+              '',
+            );
+          },
+          buildExtensions: {
+            '.dart': ['.g.dart'],
+          },
+        ),
+      ],
+      {
+        'test_package|lib/a.dart': '''
+import 'package:glob/glob.dart';
+''',
+      },
+      readerWriter: readerWriter,
+      onLog: (record) {
+        if (record.level == Level.SEVERE) {
+          logs.add(record.toString());
+        }
+      },
+      outputs: {'test_package|lib/a.g.dart': ''},
+    );
+    expect(logs, isEmpty);
+  });
 }
 
 /// Concatenates the contents of multiple text files into a single output.