Add invalidation test coverage for other inputs.

Author: davidmorgan

build_runner_core/test/invalidation/asset_input_invalidation_test.dart

@@ -0,0 +1,96 @@
+// 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';
+
+/// Invalidation tests in which the inputs are individually read arbitrary assets.
+void main() {
+  late InvalidationTester tester;
+
+  setUp(() {
+    tester = InvalidationTester();
+  });
+
+  group('a+(z) <-- a.1', () {
+    setUp(() {
+      tester.sources(['a', 'z']);
+      tester.builder(from: '', to: '.1')
+        ..readsOther('z')
+        ..writes('.1');
+    });
+
+    test('a.1 is built', () async {
+      expect(await tester.build(), Result(written: ['a.1', 'z.1']));
+    });
+
+    test('change z, a.1 is rebuilt', () async {
+      await tester.build();
+      expect(await tester.build(change: 'z'), Result(written: ['a.1', 'z.1']));
+    });
+
+    test('delete z, a.1 is rebuilt', () async {
+      await tester.build();
+      expect(
+        await tester.build(delete: 'z'),
+        // TODO(davidmorgan): a.1 should be rebuilt, but it's not. This is a
+        // regression since the last version on pub: fix it!
+        // Result(written: ['a.1'], deleted: ['z.1'])
+        Result(deleted: ['z.1']),
+      );
+    });
+
+    test('create z, a.1 is rebuilt', () async {
+      tester.sources(['a']);
+      expect(await tester.build(), Result(written: ['a.1']));
+      expect(await tester.build(create: 'z'), Result(written: ['a.1', 'z.1']));
+    });
+  });
+
+  group('a.1 <== a.2, b.3+(a.2) <== b.4', () {
+    setUp(() {
+      tester.sources(['a.1', 'b.3']);
+      tester.builder(from: '.1', to: '.2')
+        ..reads('.1')
+        ..writes('.2');
+      tester.builder(from: '.3', to: '.4')
+        ..reads('.3')
+        ..readsOther('a.2')
+        ..writes('.4');
+    });
+
+    test('a.4 is built', () async {
+      expect(await tester.build(), Result(written: ['a.2', 'b.4']));
+    });
+
+    test('change a.1, a.2+b.4 are rebuilt', () async {
+      await tester.build();
+      expect(
+        await tester.build(change: 'a.1'),
+        Result(written: ['a.2', 'b.4']),
+      );
+    });
+
+    test('delete a.1, a.2+b.4 are rebuilt', () async {
+      await tester.build();
+      expect(
+        await tester.build(delete: 'a.1'),
+        // TODO(davidmorgan): a.1 should be rebuilt, but it's not. This is a
+        // regression since the last version on pub: fix it!
+        // Result(written: ['a.2', 'b.4']),
+        Result(deleted: ['a.2']),
+      );
+    });
+
+    test('create a.1, a.2+b.4 are rebuilt', () async {
+      tester.sources(['b.3']);
+      await tester.build();
+      expect(
+        await tester.build(create: 'a.1'),
+        Result(written: ['a.2', 'b.4']),
+      );
+    });
+  });
+}

build_runner_core/test/invalidation/invalidation_tester.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:convert';
 
 import 'package:build/build.dart';
+import 'package:build_runner_core/src/changes/asset_updates.dart';
 import 'package:build_test/build_test.dart';
 import 'package:built_collection/built_collection.dart';
 import 'package:crypto/crypto.dart';
@@ -254,6 +255,11 @@ class TestBuilderBuilder {
     _builder.reads.add('$extension.dart');
   }
 
+  /// Test setup: the builder will read the asset with [name].
+  void readsOther(String name) {
+    _builder.otherReads.add(name);
+  }
+
   /// Test setup: the builder will write the asset that is [extension] applied
   /// to the primary input.
   ///
@@ -273,10 +279,19 @@ class TestBuilder implements Builder {
 
   final InvalidationTester _tester;
 
-  /// Assets that the builder will read.
+  /// Extensions of assets that the builder will read.
+  ///
+  /// The extensions are applied to the primary input asset ID with
+  /// [AssetIdExtension.replaceAllPathExtensions].
   List<String> reads = [];
 
-  /// Assets that the builder will write.
+  /// Names of assets that the builder will read.
+  List<String> otherReads = [];
+
+  /// Extensions of assets that the builder will write.
+  ///
+  /// The extensions are applied to the primary input asset ID with
+  /// [AssetIdExtension.replaceAllPathExtensions].
   List<String> writes = [];
 
   TestBuilder(this._tester, String from, Iterable<String> to, this.isOptional)
@@ -288,7 +303,15 @@ class TestBuilder implements Builder {
     for (final read in reads) {
       final readId = buildStep.inputId.replaceAllPathExtensions(read);
       content.add(read.toString());
-      content.add(await buildStep.readAsString(readId));
+      if (await buildStep.canRead(readId)) {
+        content.add(await buildStep.readAsString(readId));
+      }
+    }
+    for (final read in otherReads) {
+      content.add(read.assetId.toString());
+      if (await buildStep.canRead(read.assetId)) {
+        content.add(await buildStep.readAsString(read.assetId));
+      }
     }
     for (final write in writes) {
       final writeId = buildStep.inputId.replaceAllPathExtensions(write);