Skip snapshot build if inputs are unchanged (#11047)
Previously, the snapshot file was recomputed on every build. We now
record checksums for all snapshot inputs (which are catalogued in the
snapshot dependencies file output alongside the snapshot) and only
rebuild if the checksum for any input file has changed.
diff --git a/packages/flutter_tools/test/base/build_test.dart b/packages/flutter_tools/test/base/build_test.dart
new file mode 100644
index 0000000..ae1682a
--- /dev/null
+++ b/packages/flutter_tools/test/base/build_test.dart
@@ -0,0 +1,67 @@
+// Copyright 2017 The Chromium Authors. 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:file/memory.dart';
+import 'package:flutter_tools/src/base/build.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:test/test.dart';
+
+import '../src/context.dart';
+
+void main() {
+ group('Checksum', () {
+ group('fromFiles', () {
+ MemoryFileSystem fs;
+
+ setUp(() {
+ fs = new MemoryFileSystem();
+ });
+
+ testUsingContext('throws if any input file does not exist', () async {
+ await fs.file('a.dart').create();
+ expect(() => new Checksum.fromFiles(<String>['a.dart', 'b.dart'].toSet()), throwsA(anything));
+ }, overrides: <Type, Generator>{ FileSystem: () => fs});
+
+ testUsingContext('populates checksums for valid files', () async {
+ await fs.file('a.dart').writeAsString('This is a');
+ await fs.file('b.dart').writeAsString('This is b');
+ final Checksum checksum = new Checksum.fromFiles(<String>['a.dart', 'b.dart'].toSet());
+ final String json = checksum.toJson();
+ expect(json, '{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07c"}');
+ }, overrides: <Type, Generator>{ FileSystem: () => fs});
+ });
+
+ group('fromJson', () {
+ test('throws if JSON is invalid', () async {
+ expect(() => new Checksum.fromJson('<xml></xml>'), throwsA(anything));
+ });
+
+ test('populates checksums for valid JSON', () async {
+ final String json = '{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07c"}';
+ final Checksum checksum = new Checksum.fromJson(json);
+ expect(checksum.toJson(), '{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07c"}');
+ });
+ });
+
+ group('operator ==', () {
+ test('reports not equal if checksums do not match', () async {
+ final Checksum a = new Checksum.fromJson('{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07c"}');
+ final Checksum b = new Checksum.fromJson('{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07d"}');
+ expect(a == b, isFalse);
+ });
+
+ test('reports not equal if keys do not match', () async {
+ final Checksum a = new Checksum.fromJson('{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07c"}');
+ final Checksum b = new Checksum.fromJson('{"a.dart":"8a21a15fad560b799f6731d436c1b698","c.dart":"6f144e08b58cd0925328610fad7ac07c"}');
+ expect(a == b, isFalse);
+ });
+
+ test('reports equal if all checksums match', () async {
+ final Checksum a = new Checksum.fromJson('{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07c"}');
+ final Checksum b = new Checksum.fromJson('{"a.dart":"8a21a15fad560b799f6731d436c1b698","b.dart":"6f144e08b58cd0925328610fad7ac07c"}');
+ expect(a == b, isTrue);
+ });
+ });
+ });
+}
