Add test for invalidation with resolved inputs.

build_runner_core/lib/src/generate/single_step_reader_writer.dart

@@ -451,7 +451,7 @@ class SingleStepReaderWriter extends AssetReader
           node = _runningBuild.assetGraph.get(id)!;
         }
         return PhasedValue.generated(
-          atPhase: phase,
+          atPhase: nodePhase,
           before: '',
           node.generatedNodeState!.isSuccessfulFreshOutput
               ? await _delegate.readAsString(id)

build_runner_core/test/invalidation/invalidation_tester.dart

@@ -21,6 +21,12 @@ class InvalidationTester {
   /// The source assets on disk before the first build.
   final Set<AssetId> _sourceAssets = {};
 
+  /// Import statements.
+  ///
+  /// If an asset has an entry here then sources and generated sources will
+  /// start with the import statements specified.
+  final Map<String, List<String>> _importGraph = {};
+
   /// The builders that will run.
   final List<TestBuilder> _builders = [];
 
@@ -43,6 +49,9 @@ class InvalidationTester {
   /// The build number for "printOnFailure" output.
   int _buildNumber = 0;
 
+  /// Output number, for writing outputs that are different.
+  int _outputNumber = 0;
+
   /// Sets the assets that will be on disk before the first build.
   ///
   /// See the note on "names" in the class dartdoc.
@@ -53,6 +62,12 @@ class InvalidationTester {
     }
   }
 
+  // Sets the import graph for source files and generated files.
+  void importGraph(Map<String, List<String>> importGraph) {
+    _importGraph.clear();
+    _importGraph.addAll(importGraph);
+  }
+
   /// Adds a builder to the test.
   ///
   /// [from] and [to] are the input and output extension of the builder,
@@ -106,6 +121,13 @@ class InvalidationTester {
     _failureStrategies[name.assetId] = FailureStrategy.succeed;
   }
 
+  String _imports(AssetId id) {
+    final imports = _importGraph[_assetIdToName(id)];
+    return imports == null
+        ? ''
+        : imports.map((i) => "import '${i.pathForImport}';").join('\n');
+  }
+
   /// Does a build.
   ///
   /// For the initial build, do not pass [change] [delete] or [create].
@@ -120,7 +142,7 @@ class InvalidationTester {
         throw StateError('Do a build without change, delete or create first.');
       }
       for (final id in _sourceAssets) {
-        assets[id] = '// initial source';
+        assets[id] = '${_imports(id)}// initial source';
       }
     } else {
       // Create the new filesystem from the previous build state.
@@ -131,7 +153,8 @@ class InvalidationTester {
 
     // Make the requested updates.
     if (change != null) {
-      assets[change.assetId] = '${assets[change.assetId]}\n// changed';
+      assets[change.assetId] =
+          '${_imports(change.assetId)}}\n// ${++_outputNumber}';
     }
     if (delete != null) {
       if (assets.containsKey(delete.assetId)) {
@@ -148,7 +171,7 @@ class InvalidationTester {
       if (assets.containsKey(create.assetId)) {
         throw StateError('Asset $create to create already exists in: $assets');
       }
-      assets[create.assetId] = '// initial source';
+      assets[create.assetId] = '${_imports(create.assetId)}// initial source';
     }
 
     // Build and check what changed.
@@ -259,6 +282,11 @@ class TestBuilderBuilder {
     _builder.otherReads.add(name);
   }
 
+  /// Test setup: the builder will parse the Dart source asset with [name].
+  void resolvesOther(String name) {
+    _builder.otherResolves.add(name);
+  }
+
   /// Test setup: the builder will write the asset that is [extension] applied
   /// to the primary input.
   ///
@@ -287,6 +315,9 @@ class TestBuilder implements Builder {
   /// Names of assets that the builder will read.
   List<String> otherReads = [];
 
+  /// Names of assets that the builder will resolve.
+  List<String> otherResolves = [];
+
   /// Extensions of assets that the builder will write.
   ///
   /// The extensions are applied to the primary input asset ID with
@@ -312,14 +343,21 @@ class TestBuilder implements Builder {
         content.add(await buildStep.readAsString(read.assetId));
       }
     }
+    for (final resolve in otherResolves) {
+      content.add(resolve.assetId.toString());
+      await buildStep.resolver.libraryFor(resolve.assetId);
+    }
     for (final write in writes) {
       final writeId = buildStep.inputId.replaceAllPathExtensions(write);
       final outputStrategy =
           _tester._outputStrategies[writeId] ?? OutputStrategy.inputDigest;
+      final inputHash = base64.encode(
+        md5.convert(utf8.encode(content.join('\n\n'))).bytes,
+      );
       final output = switch (outputStrategy) {
-        OutputStrategy.fixed => '',
+        OutputStrategy.fixed => _tester._imports(writeId),
         OutputStrategy.inputDigest =>
-          '// ${base64.encode(md5.convert(utf8.encode(content.join('\n\n'))).bytes)}',
+          '${_tester._imports(writeId)}\n// $inputHash',
         OutputStrategy.none => null,
       };
       if (output != null) {
@@ -354,6 +392,9 @@ extension StringExtension on String {
   AssetId get generatedAssetId =>
       AssetId('pkg', '.dart_tool/build/generated/pkg/lib/$this.dart');
 
+  /// Maps "names" to relative import path.
+  String get pathForImport => '$this.dart';
+
   /// Displays trimmed and with two space indent.
   String get trimAndIndent => '  ${toString().trim().replaceAll('\n', '\n  ')}';
 }

build_runner_core/test/invalidation/resolved_input_invalidation_test.dart

@@ -0,0 +1,115 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:test/test.dart';
+
+import 'invalidation_tester.dart';
+
+/// In the test names:
+///
+/// - `a1 <== a2` means a1 is the primary input of a2 _and_ is an input:
+///    the builder _does_ read a1
+/// -  dart source import graphs are introduced with "resolves", so
+///    `a1 resolves: a2 --> a3 --> a4` means that the generation of a1
+///    resolves a2, which imports a3, which imports a4
+void main() {
+  late InvalidationTester tester;
+
+  setUp(() {
+    tester = InvalidationTester();
+  });
+
+  group('a.1 <== a.2, a.2 resolves: a.1 --> za --> zb', () {
+    setUp(() {
+      tester.sources(['a.1', 'za', 'zb']);
+      tester.importGraph({
+        'a.1': ['za'],
+        'za': ['zb'],
+      });
+      tester.builder(from: '.1', to: '.2')
+        ..reads('.1')
+        ..resolvesOther('a.1')
+        ..writes('.2');
+    });
+
+    test('a.2 is built', () async {
+      expect(await tester.build(), Result(written: ['a.2']));
+    });
+
+    test('change za, a.2 is rebuilt', () async {
+      await tester.build();
+      expect(await tester.build(change: 'za'), Result(written: ['a.2']));
+    });
+
+    test('change zb, a.2 is rebuilt', () async {
+      await tester.build();
+      expect(await tester.build(change: 'zb'), Result(written: ['a.2']));
+    });
+  });
+
+  // Transitive dependencies via files generated in earlier phases.
+  group('a.1 <== a.2, a.3 <== a.4, a.5 <== a.6, '
+      'a.6 resolves: z -> a.4 --> a.2', () {
+    setUp(() {
+      tester.sources(['a.1', 'a.3', 'a.5', 'z']);
+      tester.importGraph({
+        'z': ['a.4'],
+        'a.4': ['a.2'],
+      });
+      tester.builder(from: '.1', to: '.2')
+        ..reads('.1')
+        ..writes('.2');
+      tester.builder(from: '.3', to: '.4')
+        ..reads('.3')
+        ..writes('.4');
+      tester.builder(from: '.5', to: '.6')
+        ..reads('.5')
+        ..resolvesOther('a.4')
+        ..writes('.6');
+    });
+
+    test('a.6 is built', () async {
+      expect(await tester.build(), Result(written: ['a.2', 'a.4', 'a.6']));
+    });
+
+    test('change a.1, a.6 is rebuilt', () async {
+      expect(await tester.build(), Result(written: ['a.2', 'a.4', 'a.6']));
+      expect(
+        await tester.build(change: 'a.1'),
+        Result(written: ['a.2', 'a.6']),
+      );
+    });
+  });
+
+  // As previous group, but with builders in reverse order so the transitive
+  // import is not available and is not an input.
+  group('a.5 <== a.6, a.3 <== a.4, a.1 <== a.2, a.6 resolves: z -> a.4', () {
+    setUp(() {
+      tester.sources(['a.1', 'a.3', 'a.5', 'z']);
+      tester.importGraph({
+        'z': ['a.4'],
+        'a.4': ['a.2'],
+      });
+      tester.builder(from: '.5', to: '.6')
+        ..reads('.5')
+        ..resolvesOther('z')
+        ..writes('.6');
+      tester.builder(from: '.3', to: '.4')
+        ..reads('.3')
+        ..writes('.4');
+      tester.builder(from: '.1', to: '.2')
+        ..reads('.1')
+        ..writes('.2');
+    });
+
+    test('a.6 is built', () async {
+      expect(await tester.build(), Result(written: ['a.2', 'a.4', 'a.6']));
+    });
+
+    test('change a.1, a.6 is not rebuilt', () async {
+      expect(await tester.build(), Result(written: ['a.2', 'a.4', 'a.6']));
+      expect(await tester.build(change: 'a.1'), Result(written: ['a.2']));
+    });
+  });
+}