Run the Dart CLI tests from app snapshots on CI (#383)

This substantially speeds up the test time, and once we re-enable Dart
2 support is should work around dart-lang/sdk#33257.

.travis.yml

@@ -61,6 +61,8 @@ install:
 - if-specs git -C sass-spec checkout FETCH_HEAD
 - if-specs bundle install --gemfile=sass-spec/Gemfile --jobs=3 --retry=3
 
+- if [ "$TASK" = tests ]; then pub run grinder app-snapshot; fi
+
 script: tool/travis/test.sh
 
 ## Deployment

appveyor.yml

@@ -19,6 +19,10 @@ install:
       Install-Product node ''
       pub run grinder npm-package
     }
+- ps: >-
+    If ($env:NODE -eq "false") {
+      pub run grinder app-snapshot
+    }
 
 # Run this as CMD because npm's stderr will cause PowerShell to think it failed.
 - IF "%NODE%"=="true" npm install

test/cli/dart/colon_args_test.dart

@@ -10,5 +10,6 @@ import '../dart_test.dart';
 import '../shared/colon_args.dart';
 
 void main() {
+  setUpAll(ensureSnapshotUpToDate);
   sharedTests(runSass);
 }

test/cli/dart/errors_test.dart

@@ -10,5 +10,6 @@ import '../dart_test.dart';
 import '../shared/errors.dart';
 
 void main() {
+  setUpAll(ensureSnapshotUpToDate);
   sharedTests(runSass);
 }

test/cli/dart/repl_test.dart

@@ -10,5 +10,6 @@ import '../dart_test.dart';
 import '../shared/repl.dart';
 
 void main() {
+  setUpAll(ensureSnapshotUpToDate);
   sharedTests(runSass);
 }

test/cli/dart/source_maps_test.dart

@@ -10,5 +10,6 @@ import '../dart_test.dart';
 import '../shared/source_maps.dart';
 
 void main() {
+  setUpAll(ensureSnapshotUpToDate);
   sharedTests(runSass);
 }

test/cli/dart/update_test.dart

@@ -10,5 +10,6 @@ import '../dart_test.dart';
 import '../shared/update.dart';
 
 void main() {
+  setUpAll(ensureSnapshotUpToDate);
   sharedTests(runSass);
 }

test/cli/dart/watch_test.dart

@@ -10,5 +10,6 @@ import '../dart_test.dart';
 import '../shared/watch.dart';
 
 void main() {
+  setUpAll(ensureSnapshotUpToDate);
   sharedTests(runSass);
 }

test/cli/dart_test.dart

@@ -12,9 +12,19 @@ import 'package:test/test.dart';
 import 'package:test_descriptor/test_descriptor.dart' as d;
 import 'package:test_process/test_process.dart';
 
+import '../io.dart';
 import 'shared.dart';
 
+/// Paths where snapshots of the Sass binary might exist, in order of
+/// preference.
+final _snapshotPaths = [
+  p.absolute("build/sass.dart.app.snapshot"),
+  p.absolute("build/sass.dart.snapshot")
+];
+
 void main() {
+  setUpAll(ensureSnapshotUpToDate);
+
   sharedTests(runSass);
 
   test("--version prints the Sass version", () async {
@@ -24,8 +34,32 @@ void main() {
   });
 }
 
-Future<TestProcess> runSass(Iterable<String> arguments) => TestProcess.start(
-    Platform.executable,
-    ["--checked", p.absolute("bin/sass.dart")]..addAll(arguments),
-    workingDirectory: d.sandbox,
-    description: "sass");
+/// Ensures that the snapshot of the Dart executable used by [runSass] is
+/// up-to-date, if one has been generated.
+void ensureSnapshotUpToDate() {
+  for (var path in _snapshotPaths) {
+    if (new File(path).existsSync()) {
+      ensureUpToDate(path, "pub run grinder app-snapshot");
+      return;
+    }
+  }
+}
+
+Future<TestProcess> runSass(Iterable<String> arguments) {
+  var executable = _snapshotPaths.firstWhere(
+      (path) => new File(path).existsSync(),
+      orElse: () => p.absolute("bin/sass.dart"));
+
+  var args = ["--checked"];
+
+  // Work around dart-lang/sdk#33622.
+  if (Platform.isWindows) args.add("--packages=${p.absolute('.packages')}");
+
+  return TestProcess.start(
+      Platform.executable,
+      args
+        ..add(executable)
+        ..addAll(arguments),
+      workingDirectory: d.sandbox,
+      description: "sass");
+}

test/ensure_npm_package.dart

@@ -3,42 +3,16 @@
 // https://opensource.org/licenses/MIT.
 
 import 'dart:async';
-import 'dart:io';
 
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 
 import 'package:sass/src/io.dart';
 
-hybridMain(StreamChannel channel) async {
-  if (!new Directory("build/npm").existsSync()) {
-    throw "NPM package is not built. Run pub run grinder npm-package.";
-  }
-
-  var lastModified = new File("build/npm/package.json").lastModifiedSync();
-  var entriesToCheck = new Directory("lib").listSync(recursive: true).toList();
-
-  // If we have a dependency override, "pub run" will touch the lockfile to mark
-  // it as newer than the pubspec, which makes it unsuitable to use for
-  // freshness checking.
-  if (new File("pubspec.yaml")
-      .readAsStringSync()
-      .contains("dependency_overrides")) {
-    entriesToCheck.add(new File("pubspec.yaml"));
-  } else {
-    entriesToCheck.add(new File("pubspec.lock"));
-  }
-
-  for (var entry in entriesToCheck) {
-    if (entry is File) {
-      var entryLastModified = entry.lastModifiedSync();
-      if (lastModified.isBefore(entryLastModified)) {
-        throw "${entry.path} was modified after NPM package was generated.\n"
-            "Run pub run grinder before-test.";
-      }
-    }
-  }
+import 'io.dart';
 
+hybridMain(StreamChannel channel) async {
+  ensureUpToDate("build/npm/sass.dart.js", "pub run grinder npm-package");
   channel.sink.close();
 }
 

test/io.dart

@@ -0,0 +1,45 @@
+// Copyright 2018 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+
+/// Ensures that [path] (usually a compilation artifact) has been modified more
+/// recently than all this package's source files.
+///
+/// If [path] isn't up-to-date, this throws an error encouraging the user to run
+/// [commandToRun].
+void ensureUpToDate(String path, String commandToRun) {
+  // Ensure path is relative so the error messages are more readable.
+  path = p.relative(path);
+  if (!new File(path).existsSync()) {
+    throw "$path does not exist. Run $commandToRun.";
+  }
+
+  var lastModified = new File(path).lastModifiedSync();
+  var entriesToCheck = new Directory("lib").listSync(recursive: true).toList();
+
+  // If we have a dependency override, "pub run" will touch the lockfile to mark
+  // it as newer than the pubspec, which makes it unsuitable to use for
+  // freshness checking.
+  if (new File("pubspec.yaml")
+      .readAsStringSync()
+      .contains("dependency_overrides")) {
+    entriesToCheck.add(new File("pubspec.yaml"));
+  } else {
+    entriesToCheck.add(new File("pubspec.lock"));
+  }
+
+  for (var entry in entriesToCheck) {
+    if (entry is File) {
+      var entryLastModified = entry.lastModifiedSync();
+      if (lastModified.isBefore(entryLastModified)) {
+        throw "${entry.path} was modified after ${p.prettyUri(p.toUri(path))} "
+            "was generated.\n"
+            "Run pub run grinder before_test.";
+      }
+    }
+  }
+}

tool/grind/benchmark.dart

@@ -13,7 +13,7 @@ import 'standalone.dart';
 import 'utils.dart';
 
 @Task('Run benchmarks for Sass compilation speed.')
-@Depends(snapshot, appSnapshot, npmPackage)
+@Depends(snapshot, releaseAppSnapshot, npmPackage)
 benchmark() async {
   var libsass = await cloneOrPull('https://github.com/sass/libsass');
   var sassc = await cloneOrPull('https://github.com/sass/sassc');

tool/grind/standalone.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 
 import 'package:archive/archive.dart';
 import 'package:grinder/grinder.dart';
+import 'package:meta/meta.dart';
 import 'package:path/path.dart' as p;
 import 'package:http/http.dart' as http;
 
@@ -21,20 +22,32 @@ snapshot() {
   Dart.run('bin/sass.dart', vmArgs: ['--snapshot=build/sass.dart.snapshot']);
 }
 
-@Task('Build Dart application snapshot.')
-appSnapshot() {
+@Task('Build a dev-mode Dart application snapshot.')
+appSnapshot() => _appSnapshot(release: false);
+
+@Task('Build a release-mode Dart application snapshot.')
+releaseAppSnapshot() => _appSnapshot(release: true);
+
+/// Compiles Sass to an application snapshot.
+///
+/// If [release] is `true`, this compiles in checked mode. Otherwise, it
+/// compiles in unchecked mode.
+void _appSnapshot({@required bool release}) {
+  var args = [
+    '--snapshot=build/sass.dart.app.snapshot',
+    '--snapshot-kind=app-jit'
+  ];
+  // TODO(nweiz): Once we're building with Dart 2 runtime semantics, pass a flag
+  // to enable assertions rather than a flag to enable checked mode.
+  if (!release) args..add('--checked');
+
   ensureBuild();
   Dart.run('bin/sass.dart',
-      arguments: ['tool/app-snapshot-input.scss'],
-      vmArgs: [
-        '--snapshot=build/sass.dart.app.snapshot',
-        '--snapshot-kind=app-jit'
-      ],
-      quiet: true);
+      arguments: ['tool/app-snapshot-input.scss'], vmArgs: args, quiet: true);
 }
 
 @Task('Build standalone packages for all OSes.')
-@Depends(snapshot, appSnapshot)
+@Depends(snapshot, releaseAppSnapshot)
 package() async {
   var client = new http.Client();
   await Future.wait(["linux", "macos", "windows"].expand((os) => [