From acec47d410d67062b32480517452fd699d883a73 Mon Sep 17 00:00:00 2001
From: Jacob MacDonald <jakemac@google.com>
Date: Fri, 29 Apr 2016 10:35:29 -0700
Subject: [PATCH] Fix GeneratedAssetNode bug (#102)

---
 CHANGELOG.md                     |  4 ++++
 lib/src/generate/build_impl.dart |  9 +++++++--
 pubspec.yaml                     |  2 +-
 test/common/copy_builder.dart    |  6 ++++++
 test/generate/build_test.dart    | 13 +++++++++++++
 5 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 69d58f825..aef2f7923 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.3.0+1
+- Fix an AssetGraph bug where generated nodes might be created as non-generated
+  nodes if they are attempted to be read from previous build steps.
+
 ## 0.3.0
 - **BREAKING** Renamed values of three enums to be lower-case:
   `BuildType`, `BuildStatus`, and `PackageDependencyType`.
diff --git a/lib/src/generate/build_impl.dart b/lib/src/generate/build_impl.dart
index c3a7ec6c1..19ab46ff6 100644
--- a/lib/src/generate/build_impl.dart
+++ b/lib/src/generate/build_impl.dart
@@ -529,8 +529,13 @@ class BuildImpl {
           _assetGraph.addIfAbsent(input, () => new AssetNode(input));
       for (var output in expectedOutputs) {
         inputNode.outputs.add(output);
-        _assetGraph.addIfAbsent(
-            output, () => new GeneratedAssetNode(input, true, false, output));
+        var existing = _assetGraph.get(output);
+        /// If its null or of type [AssetNode], then insert a
+        /// [GeneratedAssetNode].
+        if (existing is! GeneratedAssetNode) {
+          _assetGraph.remove(output);
+          _assetGraph.add(new GeneratedAssetNode(input, true, false, output));
+        }
       }
 
       /// Skip the build step if none of the outputs need updating.
diff --git a/pubspec.yaml b/pubspec.yaml
index d12c8ece9..bc5ca1130 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: build
-version: 0.3.0
+version: 0.3.0+1
 description: A build system for Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/dart-lang/build
diff --git a/test/common/copy_builder.dart b/test/common/copy_builder.dart
index 0af9194bd..b7c8f0e43 100644
--- a/test/common/copy_builder.dart
+++ b/test/common/copy_builder.dart
@@ -20,6 +20,9 @@ class CopyBuilder implements Builder {
   /// asset.
   final AssetId copyFromAsset;
 
+  /// Will touch this asset, so that it becomes a dependency.
+  final AssetId touchAsset;
+
   /// No `build` step will complete until this future completes. It may be
   /// re-assigned in between builds.
   Future blockUntil;
@@ -29,6 +32,7 @@ class CopyBuilder implements Builder {
       this.extension: 'copy',
       this.outputPackage,
       this.copyFromAsset,
+      this.touchAsset,
       this.blockUntil});
 
   @override
@@ -42,6 +46,8 @@ class CopyBuilder implements Builder {
           : await buildStep.readAsString(copyFromAsset);
       buildStep.writeAsString(new Asset(id, content));
     }
+
+    if (touchAsset != null) await buildStep.hasInput(touchAsset);
   }
 
   @override
diff --git a/test/generate/build_test.dart b/test/generate/build_test.dart
index 50bbe2983..97c3cfdfd 100644
--- a/test/generate/build_test.dart
+++ b/test/generate/build_test.dart
@@ -82,6 +82,19 @@ void main() {
           'a|web/a.txt.clone.copy.1': 'a',
         });
       });
+
+      test('early step touches a not-yet-generated asset', () async {
+        var phases = new PhaseGroup();
+        phases.newPhase()
+          ..addAction(
+              new CopyBuilder(touchAsset: new AssetId('a', 'lib/a.txt.copy')),
+              new InputSet('a', ['lib/b.txt']));
+        phases.newPhase()
+          ..addAction(new CopyBuilder(), new InputSet('a', ['lib/a.txt']));
+
+        await testPhases(phases, {'a|lib/a.txt': 'a', 'a|lib/b.txt': 'b',},
+            outputs: {'a|lib/a.txt.copy': 'a', 'a|lib/b.txt.copy': 'b',});
+      });
     });
 
     group('inputs from other packages', () {