Merge pull request #670 from sass/merge-master

Merge master into feature.use

.travis.yml

@@ -1,34 +1,12 @@
 ## Testing
 
 # Set the language to Ruby so that we can run sass-spec tests.
-language: ruby
+language: shell
 
 env:
   global:
   - DART_CHANNEL=stable
   - DART_VERSION=latest
-  matrix:
-  # Language specs, defined in sass/sass-spec
-  - TASK=specs
-  - TASK=specs DART_CHANNEL=dev
-  - TASK=specs ASYNC=true
-
-  # Unit tests, defined in test/.
-  - TASK=tests
-  - TASK=tests DART_CHANNEL=dev
-  - TASK=tests NODE_VERSION=stable
-
-  # Keep these up-to-date with the latest LTA Node releases. They next need to be
-  # rotated October 2018. See https://github.com/nodejs/Release.
-  - TASK=tests NODE_VERSION=lts/boron
-  - TASK=tests NODE_VERSION=lts/carbon
-
-  # Miscellaneous checks.
-  - TASK=analyze
-  - TASK=format
-
-rvm:
-- 2.3.1
 
 # Only building master means that we don't run two builds for each pull request.
 branches:
@@ -43,44 +21,91 @@ cache:
   directories:
   - $HOME/.pub-cache
 
-install:
 # Install the Dart SDK.
-- curl -o dart.zip "https://storage.googleapis.com/dart-archive/channels/$DART_CHANNEL/release/$DART_VERSION/sdk/dartsdk-linux-x64-release.zip"
-- unzip dart.zip
-- export PATH="$PATH:`pwd`/dart-sdk/bin"
-- pub get
-
-# Install the Node SDK if we're running Node tests.
-- if-node() { if [ ! -z "$NODE_VERSION" ]; then "$@"; fi }
-- if-node . "$HOME/.nvm/nvm.sh"
-- if-node nvm install "$NODE_VERSION"
-- if-node nvm use "$NODE_VERSION"
-- if-node pub run grinder before-test
-
-# Download sass-spec and install its dependencies if we're running specs.
-- if-specs() { if [ "$TASK" = specs ]; then "$@"; fi }
-- if-specs export sass_spec_ref=`tool/travis/sass-spec-ref.sh`
-- if-specs git init sass-spec
-- if-specs git -C sass-spec fetch git://github.com/sass/sass-spec "$sass_spec_ref" --depth 1
-- if-specs git -C sass-spec checkout FETCH_HEAD
-- if-specs bundle install --gemfile=sass-spec/Gemfile --jobs=3 --retry=3
-
-- if [ "$TASK" = tests ]; then pub run grinder app-snapshot; fi
-
-script: tool/travis/test.sh
-
-## Deployment
+before_install:
+- tool/travis/use_dart.sh
+- export PATH="$PATH:`pwd`/dart-sdk/bin";
 
 jobs:
   include:
+  ## Testing
+
+  # Language specs, defined in sass/sass-spec. These need Ruby to run the spec
+  # runner.
+  - &specs
+    name: sass-spec | Dart stable | synchronous
+    language: ruby
+    install:
+    - export sass_spec_ref=`tool/travis/sass-spec-ref.sh`
+    - git init sass-spec
+    - git -C sass-spec fetch git://github.com/sass/sass-spec "$sass_spec_ref" --depth 1
+    - git -C sass-spec checkout FETCH_HEAD
+    - bundle install --gemfile=sass-spec/Gemfile --jobs=3 --retry=3
+    script: tool/travis/task/specs.sh
+  - <<: *specs
+    name: sass-spec | Dart dev | synchronous
+    env: DART_CHANNEL=dev
+  - <<: *specs
+    name: sass-spec | Dart stable | asynchronous
+    env: ASYNC=true
+
+  # Pure Dart unit tests, defined in test/.
+  - &dart-tests
+    name: Dart tests | Dart stable
+    install: pub run grinder app-snapshot
+    task: tool/travis/task/dart_tests.sh
+  - <<: *dart-tests
+    name: Dart tests | Dart dev
+    env: DART_CHANNEL=dev
+  - <<: *dart-tests
+    os: windows
+  - <<: *dart-tests
+    os: osx
+
+  # Unit tests that use Node.js, defined in test/.
+  #
+  # The versions should be kept up-to-date with the latest LTS Node releases.
+  # They next need to be rotated December 2019. See
+  # https://github.com/nodejs/Release.
+  #
+  # TODO(nweiz): Run Node tests on Windows when [this issue][] is fixed.
+  #
+  # [this issue]: https://travis-ci.community/t/windows-instances-hanging-before-install/250/28.
+  - &node-tests
+    name: Node tests | Dart stable | Node stable
+    language: node_js
+    node_js: stable
+    install: pub run grinder before-test
+    script: tool/travis/task/node_tests.sh
+  - <<: *node-tests
+    name: Node tests | Dart stable | Node Carbon
+    node_js: lts/carbon
+  - <<: *node-tests
+    name: Node tests | Dart stable | Node Dubnium
+    node_js: lts/dubnium
+  - <<: *node-tests
+    os: osx
+
+  # Miscellaneous checks.
+  - name: static analysis
+    language: dart
+    dart_task: {dartanalyzer: --fatal-warnings lib tool test}
+  - name: code formatting
+    language: dart
+    dart_task: dartfmt
+
+  ## Deployment
+
   # Sanity check before releasing anywhere.
   - stage: sanity check
     if: &deploy-if
       (type IN (push, api)) AND (repo = sass/dart-sass) AND tag =~ ^\d+\.\d+\.\d+([+-].*)?$
     script: pub run grinder sanity-check-before-release
 
-  # Deploy to GitHub.
+  # Deploy Linux and Windows releases to GitHub. Mac OS releases are deployed in
+  # a later stage so that we can build application snapshots on Mac OS bots.
   - stage: deploy 1
+    name: "GitHub: Windows and Linux"
     if: *deploy-if
     env: &github-env
       - GITHUB_USER=sassbot
@@ -92,7 +117,7 @@ jobs:
     script: skip # Don't run tests
     deploy:
       provider: script
-      script: pub run grinder github-release
+      script: pub run grinder github-release github-linux github-windows
       skip_cleanup: true # Don't clean up the Dart SDK.
 
       # This causes the deploy to only be build when a tag is pushed. This
@@ -108,8 +133,11 @@ jobs:
       on: {tags: true}
 
   # Deploy to npm.
-  - if: *deploy-if
+  - name: npm
+    if: *deploy-if
     script: skip
+    language: node_js
+    node_js: stable
     deploy:
       provider: script
       script: tool/travis/deploy/npm.sh
@@ -117,7 +145,8 @@ jobs:
       on: {tags: true}
 
   # Deploy to pub.
-  - if: *deploy-if
+  - name: pub
+    if: *deploy-if
     script: skip
     deploy:
       provider: script
@@ -126,7 +155,8 @@ jobs:
       on: {tags: true}
 
   # Deploy to Homebrew.
-  - if: *deploy-if
+  - name: Homebrew
+    if: *deploy-if
     env: *github-env
     script: skip
     deploy:
@@ -136,7 +166,8 @@ jobs:
       on: {tags: true}
 
   # Deploy to Chocolatey.
-  - if: *deploy-if
+  - name: Chocolatey
+    if: *deploy-if
     env:
       # CHOCO_TOKEN="..."
       - secure: "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"
@@ -148,10 +179,11 @@ jobs:
       on: {tags: true}
 
   # Redeploy sass-lang.com.
-  - if: *deploy-if
+  - name: sass-lang.com
+    if: *deploy-if
     env:
       # HEROKU_TOKEN="..."
-      - secure: "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"
+      - secure: "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"
     install: skip
     script: skip
     deploy:
@@ -164,6 +196,7 @@ jobs:
   # Deploy to Bazel. This is in a separate deploy stage because it needs to
   # install the npm package.
   - stage: deploy 2
+    name: Bazel
     if: *deploy-if
     env: *github-env
     script: skip
@@ -172,3 +205,13 @@ jobs:
       script: pub run grinder update-bazel
       skip_cleanup: true
       on: {tags: true}
+
+  - name: "GitHub: Mac OS"
+    if: *deploy-if
+    env: *github-env
+    script: skip
+    deploy:
+      provider: script
+      script: pub run grinder github-mac-os
+      skip_cleanup: true
+      on: {tags: true}

CHANGELOG.md

@@ -1,3 +1,70 @@
+## 1.20.1
+
+* No user-visible changes.
+
+## 1.20.0
+
+* Support attribute selector modifiers, such as the `i` in `[title="test" i]`.
+
+### Command-Line Interface
+
+* When compilation fails, Sass will now write the error message to the CSS
+  output as a comment and as the `content` property of a `body::before` rule so
+  it will show up in the browser (unless compiling to standard output). This can
+  be disabled with the `--no-error-css` flag, or forced even when compiling to
+  standard output with the `--error-css` flag.
+
+### Dart API
+
+* Added `SassException.toCssString()`, which returns the contents of a CSS
+  stylesheet describing the error, as above.
+
+## 1.19.0
+
+* Allow `!` in `url()`s without quotes.
+
+### Dart API
+
+* `FilesystemImporter` now doesn't change its effective directory if the working
+  directory changes, even if it's passed a relative argument.
+
+## 1.18.0
+
+* Avoid recursively listing directories when finding the canonical name of a
+  file on case-insensitive filesystems.
+
+* Fix importing files relative to `package:`-imported files.
+
+* Don't claim that "package:" URLs aren't supported when they actually are.
+
+### Command-Line Interface
+
+* Add a `--no-charset` flag. If this flag is set, Sass will never emit a
+  `@charset` declaration or a byte-order mark, even if the CSS file contains
+  non-ASCII characters.
+
+### Dart API
+
+* Add a `charset` option to `compile()`, `compileString()`, `compileAsync()` and
+  `compileStringAsync()`. If this option is set to `false`, Sass will never emit
+  a `@charset` declaration or a byte-order mark, even if the CSS file contains
+  non-ASCII characters.
+
+* Explicitly require that importers' `canonicalize()` methods be able to take
+  paths relative to their outputs as valid inputs. This isn't considered a
+  breaking change because the importer infrastructure already required this in
+  practice.
+
+## 1.17.4
+
+* Consistently parse U+000C FORM FEED, U+000D CARRIAGE RETURN, and sequences of
+  U+000D CARRIAGE RETURN followed by U+000A LINE FEED as individual newlines.
+
+### JavaScript API
+
+* Add a `sass.types.Error` constructor as an alias for `Error`. This makes our
+  custom function API compatible with Node Sass's.
+
 ## 1.17.3
 
 * Fix an edge case where slash-separated numbers were written to the stylesheet

appveyor.yml

@@ -8,34 +8,14 @@ branches:
     # Semantic version tags and legacy branches of the form "1.2.x".
     - "/^\\d+\\.\\d+\\.(\\d+([+-].*)?|x)$/"
 
-# Don't run specs because sass-spec doesn't support Windows. They're also
-# supposed to be platform-independent.
-environment:
-  matrix:
-  - {TASK: tests, NODE: false}
-  - {TASK: tests, NODE: true}
-
 install:
 - choco install dart-sdk
 - refreshenv
 - pub get
-- ps: >-
-    If ($env:NODE -eq "true") {
-      Install-Product node ''
-      pub run grinder npm-package
-    }
-- ps: >-
-    If ($env:NODE -eq "false") {
-      pub run grinder app-snapshot
-    }
+- ps: Install-Product node ''
+- pub run grinder npm-package
+- npm install
 
-# Run this as CMD because npm's stderr will cause PowerShell to think it failed.
-- IF "%NODE%"=="true" npm install
-
-test_script:
-- ps: >-
-    If ($env:NODE -eq "true") {
-      pub run test -t node
-    } Else {
-      pub run test -p vm -x node
-    }
+# Only run Node tests on Windows because they won't work on Travis. See
+# https://travis-ci.community/t/windows-instances-hanging-before-install/250/28.
+test_script: pub run test -t node

lib/sass.dart

@@ -70,6 +70,13 @@ export 'src/visitor/serialize.dart' show OutputStyle;
 ///
 /// [`source_maps`]: https://pub.dartlang.org/packages/source_maps
 ///
+/// If [charset] is `true`, this will include a `@charset` declaration or a
+/// UTF-8 [byte-order mark][] if the stylesheet contains any non-ASCII
+/// characters. Otherwise, it will never include a `@charset` declaration or a
+/// byte-order mark.
+///
+/// [byte-order mark]: https://en.wikipedia.org/wiki/Byte_order_mark#UTF-8
+///
 /// This parameter is meant to be used as an out parameter, so that users who
 /// want access to the source map can get it. For example:
 ///
@@ -87,7 +94,8 @@ String compile(String path,
     SyncPackageResolver packageResolver,
     Iterable<Callable> functions,
     OutputStyle style,
-    void sourceMap(SingleMapping map)}) {
+    void sourceMap(SingleMapping map),
+    bool charset = true}) {
   logger ??= Logger.stderr(color: color);
   var result = c.compile(path,
       logger: logger,
@@ -97,7 +105,8 @@ String compile(String path,
           packageResolver: packageResolver),
       functions: functions,
       style: style,
-      sourceMap: sourceMap != null);
+      sourceMap: sourceMap != null,
+      charset: charset);
   if (sourceMap != null) sourceMap(result.sourceMap);
   return result.css;
 }
@@ -149,6 +158,13 @@ String compile(String path,
 ///
 /// [`source_maps`]: https://pub.dartlang.org/packages/source_maps
 ///
+/// If [charset] is `true`, this will include a `@charset` declaration or a
+/// UTF-8 [byte-order mark][] if the stylesheet contains any non-ASCII
+/// characters. Otherwise, it will never include a `@charset` declaration or a
+/// byte-order mark.
+///
+/// [byte-order mark]: https://en.wikipedia.org/wiki/Byte_order_mark#UTF-8
+///
 /// This parameter is meant to be used as an out parameter, so that users who
 /// want access to the source map can get it. For example:
 ///
@@ -170,6 +186,7 @@ String compileString(String source,
     Importer importer,
     url,
     void sourceMap(SingleMapping map),
+    bool charset = true,
     @Deprecated("Use syntax instead.") bool indented = false}) {
   logger ??= Logger.stderr(color: color);
   var result = c.compileString(source,
@@ -183,7 +200,8 @@ String compileString(String source,
       style: style,
       importer: importer,
       url: url,
-      sourceMap: sourceMap != null);
+      sourceMap: sourceMap != null,
+      charset: charset);
   if (sourceMap != null) sourceMap(result.sourceMap);
   return result.css;
 }
@@ -233,6 +251,7 @@ Future<String> compileStringAsync(String source,
     AsyncImporter importer,
     url,
     void sourceMap(SingleMapping map),
+    bool charset = true,
     @Deprecated("Use syntax instead.") bool indented = false}) async {
   logger ??= Logger.stderr(color: color);
   var result = await c.compileStringAsync(source,
@@ -246,7 +265,8 @@ Future<String> compileStringAsync(String source,
       style: style,
       importer: importer,
       url: url,
-      sourceMap: sourceMap != null);
+      sourceMap: sourceMap != null,
+      charset: charset);
   if (sourceMap != null) sourceMap(result.sourceMap);
   return result.css;
 }

lib/src/ast/selector/attribute.dart

@@ -27,15 +27,27 @@ class AttributeSelector extends SimpleSelector {
   /// regardless of this value. It's `null` if and only if [op] is `null`.
   final String value;
 
+  /// The modifier which indicates how the attribute selector should be
+  /// processed.
+  ///
+  /// See for example [case-sensitivity][] modifiers.
+  ///
+  /// [case-sensitivity]: https://www.w3.org/TR/selectors-4/#attribute-case
+  ///
+  /// If [op] is `null`, this is always `null` as well.
+  final String modifier;
+
   /// Creates an attribute selector that matches any element with a property of
   /// the given name.
   AttributeSelector(this.name)
       : op = null,
-        value = null;
+        value = null,
+        modifier = null;
 
   /// Creates an attribute selector that matches an element with a property
   /// named [name], whose value matches [value] based on the semantics of [op].
-  AttributeSelector.withOperator(this.name, this.op, this.value);
+  AttributeSelector.withOperator(this.name, this.op, this.value,
+      {this.modifier});
 
   T accept<T>(SelectorVisitor<T> visitor) =>
       visitor.visitAttributeSelector(this);
@@ -44,9 +56,11 @@ class AttributeSelector extends SimpleSelector {
       other is AttributeSelector &&
       other.name == name &&
       other.op == op &&
-      other.value == value;
+      other.value == value &&
+      other.modifier == modifier;
 
-  int get hashCode => name.hashCode ^ op.hashCode ^ value.hashCode;
+  int get hashCode =>
+      name.hashCode ^ op.hashCode ^ value.hashCode ^ modifier.hashCode;
 }
 
 /// An operator that defines the semantics of an [AttributeSelector].

lib/src/async_compile.dart

@@ -36,7 +36,8 @@ Future<CompileResult> compileAsync(String path,
     bool useSpaces = true,
     int indentWidth,
     LineFeed lineFeed,
-    bool sourceMap = false}) async {
+    bool sourceMap = false,
+    bool charset = true}) async {
   // If the syntax is different than the importer would default to, we have to
   // parse the file manually and we can't store it in the cache.
   Stylesheet stylesheet;
@@ -62,7 +63,8 @@ Future<CompileResult> compileAsync(String path,
       useSpaces,
       indentWidth,
       lineFeed,
-      sourceMap);
+      sourceMap,
+      charset);
 }
 
 /// Like [compileStringAsync] in `lib/sass.dart`, but provides more options to
@@ -84,7 +86,8 @@ Future<CompileResult> compileStringAsync(String source,
     int indentWidth,
     LineFeed lineFeed,
     url,
-    bool sourceMap = false}) async {
+    bool sourceMap = false,
+    bool charset = true}) async {
   var stylesheet =
       Stylesheet.parse(source, syntax ?? Syntax.scss, url: url, logger: logger);
 
@@ -99,7 +102,8 @@ Future<CompileResult> compileStringAsync(String source,
       useSpaces,
       indentWidth,
       lineFeed,
-      sourceMap);
+      sourceMap,
+      charset);
 }
 
 /// Compiles [stylesheet] and returns its result.
@@ -116,7 +120,8 @@ Future<CompileResult> _compileStylesheet(
     bool useSpaces,
     int indentWidth,
     LineFeed lineFeed,
-    bool sourceMap) async {
+    bool sourceMap,
+    bool charset) async {
   var evaluateResult = await evaluateAsync(stylesheet,
       importCache: importCache,
       nodeImporter: nodeImporter,
@@ -130,7 +135,8 @@ Future<CompileResult> _compileStylesheet(
       useSpaces: useSpaces,
       indentWidth: indentWidth,
       lineFeed: lineFeed,
-      sourceMap: sourceMap);
+      sourceMap: sourceMap,
+      charset: charset);
 
   if (serializeResult.sourceMap != null && importCache != null) {
     // TODO(nweiz): Don't explicitly use a type parameter when dart-lang/sdk#25490

lib/src/compile.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_compile.dart.
 // See tool/synchronize.dart for details.
 //
-// Checksum: 2bb00947655b3add16335253802a82188d730595
+// Checksum: ea78ec4431055c1d222e52f4ea54a9659c4df11f
 //
 // ignore_for_file: unused_import
 
@@ -45,7 +45,8 @@ CompileResult compile(String path,
     bool useSpaces = true,
     int indentWidth,
     LineFeed lineFeed,
-    bool sourceMap = false}) {
+    bool sourceMap = false,
+    bool charset = true}) {
   // If the syntax is different than the importer would default to, we have to
   // parse the file manually and we can't store it in the cache.
   Stylesheet stylesheet;
@@ -71,7 +72,8 @@ CompileResult compile(String path,
       useSpaces,
       indentWidth,
       lineFeed,
-      sourceMap);
+      sourceMap,
+      charset);
 }
 
 /// Like [compileString] in `lib/sass.dart`, but provides more options to
@@ -93,7 +95,8 @@ CompileResult compileString(String source,
     int indentWidth,
     LineFeed lineFeed,
     url,
-    bool sourceMap = false}) {
+    bool sourceMap = false,
+    bool charset = true}) {
   var stylesheet =
       Stylesheet.parse(source, syntax ?? Syntax.scss, url: url, logger: logger);
 
@@ -108,7 +111,8 @@ CompileResult compileString(String source,
       useSpaces,
       indentWidth,
       lineFeed,
-      sourceMap);
+      sourceMap,
+      charset);
 }
 
 /// Compiles [stylesheet] and returns its result.
@@ -125,7 +129,8 @@ CompileResult _compileStylesheet(
     bool useSpaces,
     int indentWidth,
     LineFeed lineFeed,
-    bool sourceMap) {
+    bool sourceMap,
+    bool charset) {
   var evaluateResult = evaluate(stylesheet,
       importCache: importCache,
       nodeImporter: nodeImporter,
@@ -139,7 +144,8 @@ CompileResult _compileStylesheet(
       useSpaces: useSpaces,
       indentWidth: indentWidth,
       lineFeed: lineFeed,
-      sourceMap: sourceMap);
+      sourceMap: sourceMap,
+      charset: charset);
 
   if (serializeResult.sourceMap != null && importCache != null) {
     // TODO(nweiz): Don't explicitly use a type parameter when dart-lang/sdk#25490

lib/src/exception.dart

@@ -2,10 +2,13 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
+import 'package:charcode/charcode.dart';
 import 'package:source_span/source_span.dart';
 import 'package:stack_trace/stack_trace.dart';
+import 'package:term_glyph/term_glyph.dart' as term_glyph;
 
 import 'utils.dart';
+import 'value.dart';
 
 /// An exception thrown by Sass.
 class SassException extends SourceSpanException {
@@ -30,6 +33,48 @@ class SassException extends SourceSpanException {
     }
     return buffer.toString();
   }
+
+  /// Returns the contents of a CSS stylesheet that will display this error
+  /// message above the current page.
+  String toCssString() {
+    // Don't render the error message in Unicode for the inline comment, since
+    // we can't be sure the user's default encoding is UTF-8.
+    var wasAscii = term_glyph.ascii;
+    term_glyph.ascii = true;
+    // Replace comment-closing sequences in the error message with
+    // visually-similar sequences that won't actually close the comment.
+    var commentMessage = toString(color: false).replaceAll("*/", "*∕");
+    term_glyph.ascii = wasAscii;
+
+    // For the string comment, render all non-ASCII characters as escape
+    // sequences so that they'll show up even if the HTTP headers are set
+    // incorrectly.
+    var stringMessage = StringBuffer();
+    for (var rune in SassString(toString(color: false)).toString().runes) {
+      if (rune > 0xFF) {
+        stringMessage
+          ..writeCharCode($backslash)
+          ..write(rune.toRadixString(16))
+          ..writeCharCode($space);
+      } else {
+        stringMessage.writeCharCode(rune);
+      }
+    }
+
+    return """
+/* ${commentMessage.split("\n").join("\n * ")} */
+
+body::before {
+  font-family: "Source Code Pro", "SF Mono", Monaco, Inconsolata, "Fira Mono",
+      "Droid Sans Mono", monospace, monospace;
+  white-space: pre;
+  display: block;
+  padding: 1em;
+  margin-bottom: 1em;
+  border-bottom: 2px solid black;
+  content: $stringMessage;
+}""";
+  }
 }
 
 /// An exception thrown by Sass while evaluating a stylesheet.

lib/src/executable.dart

@@ -69,7 +69,9 @@ main(List<String> args) async {
         // dart-lang/sdk#33400.
         () {
           try {
-            if (destination != null) deleteFile(destination);
+            if (destination != null && !options.emitErrorCss) {
+              deleteFile(destination);
+            }
           } on FileSystemException {
             // If the file doesn't exist, that's fine.
           }

lib/src/executable/compile_stylesheet.dart

@@ -10,12 +10,13 @@ import 'package:source_maps/source_maps.dart';
 
 import '../async_import_cache.dart';
 import '../compile.dart';
-import '../visitor/serialize.dart';
+import '../exception.dart';
 import '../importer/filesystem.dart';
 import '../io.dart';
 import '../stylesheet_graph.dart';
 import '../syntax.dart';
 import '../utils.dart';
+import '../visitor/serialize.dart';
 import 'options.dart';
 
 /// Compiles the stylesheet at [source] to [destination].
@@ -56,39 +57,55 @@ Future compileStylesheet(ExecutableOptions options, StylesheetGraph graph,
   }
 
   CompileResult result;
-  if (options.asynchronous) {
-    var importCache = AsyncImportCache([],
-        loadPaths: options.loadPaths, logger: options.logger);
+  try {
+    if (options.asynchronous) {
+      var importCache = AsyncImportCache([],
+          loadPaths: options.loadPaths, logger: options.logger);
 
-    result = source == null
-        ? await compileStringAsync(await readStdin(),
-            syntax: syntax,
-            logger: options.logger,
-            importCache: importCache,
-            importer: FilesystemImporter('.'),
-            style: options.style,
-            sourceMap: options.emitSourceMap)
-        : await compileAsync(source,
-            syntax: syntax,
-            logger: options.logger,
-            importCache: importCache,
-            style: options.style,
-            sourceMap: options.emitSourceMap);
-  } else {
-    result = source == null
-        ? compileString(await readStdin(),
-            syntax: syntax,
-            logger: options.logger,
-            importCache: graph.importCache,
-            importer: FilesystemImporter('.'),
-            style: options.style,
-            sourceMap: options.emitSourceMap)
-        : compile(source,
-            syntax: syntax,
-            logger: options.logger,
-            importCache: graph.importCache,
-            style: options.style,
-            sourceMap: options.emitSourceMap);
+      result = source == null
+          ? await compileStringAsync(await readStdin(),
+              syntax: syntax,
+              logger: options.logger,
+              importCache: importCache,
+              importer: FilesystemImporter('.'),
+              style: options.style,
+              sourceMap: options.emitSourceMap,
+              charset: options.charset)
+          : await compileAsync(source,
+              syntax: syntax,
+              logger: options.logger,
+              importCache: importCache,
+              style: options.style,
+              sourceMap: options.emitSourceMap,
+              charset: options.charset);
+    } else {
+      result = source == null
+          ? compileString(await readStdin(),
+              syntax: syntax,
+              logger: options.logger,
+              importCache: graph.importCache,
+              importer: FilesystemImporter('.'),
+              style: options.style,
+              sourceMap: options.emitSourceMap,
+              charset: options.charset)
+          : compile(source,
+              syntax: syntax,
+              logger: options.logger,
+              importCache: graph.importCache,
+              style: options.style,
+              sourceMap: options.emitSourceMap,
+              charset: options.charset);
+    }
+  } on SassException catch (error) {
+    if (options.emitErrorCss) {
+      if (destination == null) {
+        print(error.toCssString());
+      } else {
+        ensureDir(p.dirname(destination));
+        writeFile(destination, error.toCssString() + "\n");
+      }
+    }
+    rethrow;
   }
 
   var css = result.css;

lib/src/executable/options.dart

@@ -55,6 +55,13 @@ class ExecutableOptions {
           help: 'Output style.',
           allowed: ['expanded', 'compressed'],
           defaultsTo: 'expanded')
+      ..addFlag('charset',
+          help: 'Emit a @charset or BOM for CSS with non-ASCII characters.',
+          defaultsTo: true)
+      ..addFlag('error-css',
+          help: 'When an error occurs, emit a stylesheet describing it.\n'
+              'Defaults to true when compiling to a file.',
+          defaultsTo: null)
       ..addFlag('update',
           help: 'Only compile out-of-date stylesheets.', negatable: false);
 
@@ -171,6 +178,10 @@ class ExecutableOptions {
       ? OutputStyle.compressed
       : OutputStyle.expanded;
 
+  /// Whether to include a `@charset` declaration or a BOM if the stylesheet
+  /// contains any non-ASCII characters.
+  bool get charset => _options['charset'] as bool;
+
   /// The set of paths Sass in which should look for imported files.
   List<String> get loadPaths => _options['load-path'] as List<String>;
 
@@ -193,6 +204,11 @@ class ExecutableOptions {
   /// error.
   bool get stopOnError => _options['stop-on-error'] as bool;
 
+  /// Whether to emit error messages as CSS stylesheets
+  bool get emitErrorCss =>
+      _options['error-css'] as bool ??
+      sourcesToDestinations.values.any((destination) => destination != null);
+
   /// A map from source paths to the destination paths where the compiled CSS
   /// should be written.
   ///
@@ -356,7 +372,7 @@ class ExecutableOptions {
   /// [destination] directories.
   Map<String, String> _listSourceDirectory(String source, String destination) {
     var map = <String, String>{};
-    for (var path in listDir(source)) {
+    for (var path in listDir(source, recursive: true)) {
       var basename = p.basename(path);
       if (basename.startsWith("_")) continue;
 

lib/src/executable/watch.dart

@@ -74,7 +74,7 @@ class _Watcher {
           ifModified: ifModified);
       return true;
     } on SassException catch (error, stackTrace) {
-      _delete(destination);
+      if (!_options.emitErrorCss) _delete(destination);
       _printError(error.toString(color: _options.color), stackTrace);
       exitCode = 65;
       return false;

lib/src/importer/async.dart

@@ -68,8 +68,10 @@ abstract class AsyncImporter {
   ///
   /// If no stylesheets are found, the importer should return `null`.
   ///
-  /// Sass assumes that calling [canonicalize] multiple times with the same URL
-  /// will return the same result.
+  /// Calling [canonicalize] multiple times with the same URL must return the
+  /// same result. Calling [canonicalize] with a URL returned by [canonicalize]
+  /// must return that URL. Calling [canonicalize] with a URL relative to one
+  /// returned by [canonicalize] must return a meaningful result.
   FutureOr<Uri> canonicalize(Uri url);
 
   /// Loads the Sass text for the given [url], or returns `null` if

lib/src/importer/filesystem.dart

@@ -18,7 +18,7 @@ class FilesystemImporter extends Importer {
   final String _loadPath;
 
   /// Creates an importer that loads files relative to [loadPath].
-  FilesystemImporter(this._loadPath);
+  FilesystemImporter(String loadPath) : _loadPath = p.absolute(loadPath);
 
   Uri canonicalize(Uri url) {
     if (url.scheme != 'file' && url.scheme != '') return null;

lib/src/importer/package.dart

@@ -29,6 +29,7 @@ class PackageImporter extends Importer {
   PackageImporter(this._packageResolver);
 
   Uri canonicalize(Uri url) {
+    if (url.scheme == 'file') return _filesystemImporter.canonicalize(url);
     if (url.scheme != 'package') return null;
 
     var resolved = _packageResolver.resolveUri(url);

lib/src/io/interface.dart

@@ -79,9 +79,11 @@ bool dirExists(String path) => null;
 /// necessary.
 void ensureDir(String path) => null;
 
-/// Recursively lists the files (not sub-directories) of the directory at
-/// [path].
-Iterable<String> listDir(String path) => null;
+/// Lists the files (not sub-directories) in the directory at [path].
+///
+/// If [recursive] is `true`, this lists files in directories transitively
+/// beneath [path] as well.
+Iterable<String> listDir(String path, {bool recursive = false}) => null;
 
 /// Returns the modification time of the file at [path].
 DateTime modificationTime(String path) => null;

lib/src/io/node.dart

@@ -191,14 +191,23 @@ void ensureDir(String path) {
   });
 }
 
-Iterable<String> listDir(String path) {
-  Iterable<String> list(String parent) =>
-      _fs.readdirSync(parent).expand((child) {
-        var path = p.join(parent, child as String);
-        return dirExists(path) ? listDir(path) : [path];
-      });
+Iterable<String> listDir(String path, {bool recursive = false}) {
+  return _systemErrorToFileSystemException(() {
+    if (!recursive) {
+      return _fs
+          .readdirSync(path)
+          .map((child) => p.join(path, child as String))
+          .where((child) => !dirExists(child));
+    } else {
+      Iterable<String> list(String parent) =>
+          _fs.readdirSync(parent).expand((child) {
+            var path = p.join(parent, child as String);
+            return dirExists(path) ? list(path) : [path];
+          });
 
-  return _systemErrorToFileSystemException(() => list(path));
+      return list(path);
+    }
+  });
 }
 
 DateTime modificationTime(String path) =>

lib/src/io/vm.dart

@@ -71,10 +71,11 @@ bool dirExists(String path) => io.Directory(path).existsSync();
 
 void ensureDir(String path) => io.Directory(path).createSync(recursive: true);
 
-Iterable<String> listDir(String path) => io.Directory(path)
-    .listSync(recursive: true)
-    .where((entity) => entity is io.File)
-    .map((entity) => entity.path);
+Iterable<String> listDir(String path, {bool recursive = false}) =>
+    io.Directory(path)
+        .listSync(recursive: recursive)
+        .where((entity) => entity is io.File)
+        .map((entity) => entity.path);
 
 DateTime modificationTime(String path) {
   var stat = io.FileStat.statSync(path);
@@ -93,7 +94,7 @@ Future<Stream<WatchEvent>> watchDir(String path, {bool poll = false}) async {
   // triggers but the caller can still listen at their leisure.
   var stream = SubscriptionStream<WatchEvent>(watcher.events
       .transform(const SingleSubscriptionTransformer<WatchEvent, WatchEvent>())
-      .listen((e) => print(e)));
+      .listen(null));
   await watcher.ready;
 
   return stream;

lib/src/node.dart

@@ -56,7 +56,8 @@ void main() {
       Map: mapConstructor,
       Null: nullConstructor,
       Number: numberConstructor,
-      String: stringConstructor);
+      String: stringConstructor,
+      Error: jsErrorConstructor);
 }
 
 /// Converts Sass to CSS.

lib/src/node/types.dart

@@ -14,6 +14,8 @@ class Types {
   external set Null(function);
   external set Number(function);
   external set String(function);
+  external set Error(function);
 
-  external factory Types({Boolean, Color, List, Map, Null, Number, String});
+  external factory Types(
+      {Boolean, Color, List, Map, Null, Number, String, Error});
 }

lib/src/node/utils.dart

@@ -34,10 +34,10 @@ bool isUndefined(value) => _isUndefined.call(value) as bool;
 final _isUndefined = JSFunction("value", "return value === undefined;");
 
 @JS("Error")
-external Function get _JSError;
+external Function get jsErrorConstructor;
 
 /// Returns whether [value] is a JS Error object.
-bool isJSError(value) => instanceof(value, _JSError);
+bool isJSError(value) => instanceof(value, jsErrorConstructor);
 
 /// Invokes [function] with [thisArg] as `this`.
 Object call2(JSFunction function, Object thisArg, Object arg1, Object arg2) =>

lib/src/node/value.dart

@@ -5,6 +5,7 @@
 import 'dart:js_util';
 
 import '../value.dart';
+import 'utils.dart';
 import 'value/color.dart';
 import 'value/list.dart';
 import 'value/map.dart';
@@ -20,11 +21,14 @@ export 'value/number.dart';
 export 'value/string.dart';
 
 /// Unwraps a value wrapped with [wrapValue].
+///
+/// If [object] is a JS error, throws it.
 Value unwrapValue(object) {
   if (object != null) {
     if (object is Value) return object;
     var value = getProperty(object, 'dartValue');
     if (value != null && value is Value) return value;
+    if (isJSError(object)) throw object;
   }
   throw "$object must be a Sass value type.";
 }

lib/src/parse/sass.dart

@@ -155,6 +155,7 @@ class SassParser extends StylesheetParser {
       // Ignore empty lines.
       case $cr:
       case $lf:
+      case $ff:
         return null;
 
       case $dollar:
@@ -282,8 +283,8 @@ class SassParser extends StylesheetParser {
       if (_peekIndentation() <= parentIndentation) break;
 
       // Preserve empty lines.
-      while (isNewline(scanner.peekChar(1))) {
-        scanner.readChar();
+      while (_lookingAtDoubleNewline()) {
+        _expectNewline();
         buffer.writeln();
         buffer.write(" *");
       }
@@ -315,7 +316,12 @@ class SassParser extends StylesheetParser {
       case $semicolon:
         scanner.error("semicolons aren't allowed in the indented syntax.");
         return;
+      case $cr:
+        scanner.readChar();
+        if (scanner.peekChar() == $lf) scanner.readChar();
+        return;
       case $lf:
+      case $ff:
         scanner.readChar();
         return;
       default:
@@ -323,6 +329,21 @@ class SassParser extends StylesheetParser {
     }
   }
 
+  /// Returns whether the scanner is immediately before *two* newlines.
+  bool _lookingAtDoubleNewline() {
+    switch (scanner.peekChar()) {
+      case $cr:
+        var nextChar = scanner.peekChar(1);
+        if (nextChar == $lf) return isNewline(scanner.peekChar(2));
+        return nextChar == $cr || nextChar == $ff;
+      case $lf:
+      case $ff:
+        return isNewline(scanner.peekChar(1));
+      default:
+        return false;
+    }
+  }
+
   /// As long as the scanner's position is indented beneath the starting line,
   /// runs [body] to consume the next statement.
   void _whileIndentedLower(void body()) {

lib/src/parse/scss.dart

@@ -184,6 +184,16 @@ class ScssParser extends StylesheetParser {
           buffer.writeCharCode(scanner.readChar());
           return LoudComment(buffer.interpolation(scanner.spanFrom(start)));
 
+        case $cr:
+          scanner.readChar();
+          if (scanner.peekChar() != $lf) buffer.writeCharCode($lf);
+          break;
+
+        case $ff:
+          scanner.readChar();
+          buffer.writeCharCode($lf);
+          break;
+
         default:
           buffer.writeCharCode(scanner.readChar());
           break;

lib/src/parse/selector.dart

@@ -201,8 +201,13 @@ class SelectorParser extends Parser {
         : identifier();
     whitespace();
 
+    var modifier = isAlphabetic(scanner.peekChar())
+        ? String.fromCharCode(scanner.readChar())
+        : null;
+
     scanner.expectChar($rbracket);
-    return AttributeSelector.withOperator(name, operator, value);
+    return AttributeSelector.withOperator(name, operator, value,
+        modifier: modifier);
   }
 
   /// Consumes a qualified name as part of an attribute selector.

lib/src/parse/stylesheet.dart

@@ -2621,7 +2621,8 @@ relase. For details, see http://bit.ly/moz-document.
       var next = scanner.peekChar();
       if (next == null) {
         break;
-      } else if (next == $percent ||
+      } else if (next == $exclamation ||
+          next == $percent ||
           next == $ampersand ||
           (next >= $asterisk && next <= $tilde) ||
           next >= 0x0080) {

lib/src/value/color.dart

@@ -133,7 +133,7 @@ class SassColor extends Value implements ext.SassColor {
   /// Computes [_hue], [_saturation], and [_value] based on [red], [green], and
   /// [blue].
   void _rgbToHsl() {
-    // Algorithm from http://en.wikipedia.org/wiki/HSL_and_HSV#Conversion_from_RGB_to_HSL_or_HSV
+    // Algorithm from https://en.wikipedia.org/wiki/HSL_and_HSV#RGB_to_HSL_and_HSV
     var scaledRed = red / 255;
     var scaledGreen = green / 255;
     var scaledBlue = blue / 255;
@@ -166,7 +166,7 @@ class SassColor extends Value implements ext.SassColor {
   /// Computes [_red], [_green], and [_blue] based on [hue], [saturation], and
   /// [value].
   void _hslToRgb() {
-    // Algorithm from the CSS3 spec: http://www.w3.org/TR/css3-color/#hsl-color.
+    // Algorithm from the CSS3 spec: https://www.w3.org/TR/css3-color/#hsl-color.
     var scaledHue = hue / 360;
     var scaledSaturation = saturation / 100;
     var scaledLightness = lightness / 100;

lib/src/visitor/async_evaluate.dart

@@ -29,6 +29,7 @@ import '../extend/extension.dart';
 import '../importer.dart';
 import '../importer/node.dart';
 import '../importer/utils.dart';
+import '../io.dart';
 import '../logger.dart';
 import '../parse/keyframe_selector.dart';
 import '../syntax.dart';
@@ -1063,7 +1064,7 @@ class _EvaluateVisitor
         if (tuple != null) return tuple;
       }
 
-      if (url.startsWith('package:')) {
+      if (url.startsWith('package:') && isNode) {
         // Special-case this error message, since it's tripped people up in the
         // past.
         throw "\"package:\" URLs aren't supported on this platform.";

lib/src/visitor/evaluate.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_evaluate.dart.
 // See tool/synchronize.dart for details.
 //
-// Checksum: 4de442e73c75611a675e2fd0d8962219f1ceffd7
+// Checksum: ef520a902171c8d105ece12e7c84889e34f95d80
 //
 // ignore_for_file: unused_import
 
@@ -38,6 +38,7 @@ import '../extend/extension.dart';
 import '../importer.dart';
 import '../importer/node.dart';
 import '../importer/utils.dart';
+import '../io.dart';
 import '../logger.dart';
 import '../parse/keyframe_selector.dart';
 import '../syntax.dart';
@@ -1065,7 +1066,7 @@ class _EvaluateVisitor
         if (tuple != null) return tuple;
       }
 
-      if (url.startsWith('package:')) {
+      if (url.startsWith('package:') && isNode) {
         // Special-case this error message, since it's tripped people up in the
         // past.
         throw "\"package:\" URLs aren't supported on this platform.";

lib/src/visitor/recursive_ast.dart

@@ -0,0 +1,80 @@
+// Copyright 2019 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 '../ast/sass.dart';
+import 'interface/expression.dart';
+import 'recursive_statement.dart';
+
+/// A visitor that recursively traverses each statement and expression in a Sass
+/// AST.
+///
+/// This extends [RecursiveStatementVisitor] to traverse each expression in
+/// addition to each statement.
+///
+/// The default implementation of the visit methods all return `null`.
+abstract class RecursiveAstVisitor<T> extends RecursiveStatementVisitor<T>
+    implements ExpressionVisitor<T> {
+  void visitExpression(Expression expression) {
+    expression.accept(this);
+  }
+
+  T visitBinaryOperationExpression(BinaryOperationExpression node) {
+    node.left.accept(this);
+    node.right.accept(this);
+    return null;
+  }
+
+  T visitBooleanExpression(BooleanExpression node) => null;
+
+  T visitColorExpression(ColorExpression node) => null;
+
+  T visitFunctionExpression(FunctionExpression node) {
+    visitInterpolation(node.name);
+    visitArgumentInvocation(node.arguments);
+    return null;
+  }
+
+  T visitIfExpression(IfExpression node) {
+    visitArgumentInvocation(node.arguments);
+    return null;
+  }
+
+  T visitListExpression(ListExpression node) {
+    for (var item in node.contents) {
+      item.accept(this);
+    }
+    return null;
+  }
+
+  T visitMapExpression(MapExpression node) {
+    for (var pair in node.pairs) {
+      pair.item1.accept(this);
+      pair.item2.accept(this);
+    }
+    return null;
+  }
+
+  T visitNullExpression(NullExpression node) => null;
+
+  T visitNumberExpression(NumberExpression node) => null;
+
+  T visitParenthesizedExpression(ParenthesizedExpression node) =>
+      node.expression.accept(this);
+
+  T visitSelectorExpression(SelectorExpression node) => null;
+
+  T visitStringExpression(StringExpression node) {
+    visitInterpolation(node.text);
+    return null;
+  }
+
+  T visitUnaryOperationExpression(UnaryOperationExpression node) =>
+      node.operand.accept(this);
+
+  T visitUseRule(UseRule node) => null;
+
+  T visitValueExpression(ValueExpression node) => null;
+
+  T visitVariableExpression(VariableExpression node) => null;
+}

lib/src/visitor/recursive_statement.dart

@@ -137,6 +137,8 @@ abstract class RecursiveStatementVisitor<T> implements StatementVisitor<T> {
     return visitChildren(node);
   }
 
+  T visitUseRule(UseRule node) => null;
+
   T visitVariableDeclaration(VariableDeclaration node) {
     visitExpression(node.expression);
     return null;

lib/src/visitor/serialize.dart

@@ -39,13 +39,17 @@ import 'interface/value.dart';
 ///
 /// If [sourceMap] is `true`, the returned [SerializeResult] will contain a
 /// source map indicating how the original Sass files map to the compiled CSS.
+///
+/// If [charset] is `true`, this will include a `@charset` declaration or a BOM
+/// if the stylesheet contains any non-ASCII characters.
 SerializeResult serialize(CssNode node,
     {OutputStyle style,
     bool inspect = false,
     bool useSpaces = true,
     int indentWidth,
     LineFeed lineFeed,
-    bool sourceMap = false}) {
+    bool sourceMap = false,
+    bool charset = true}) {
   indentWidth ??= 2;
   var visitor = _SerializeVisitor(
       style: style,
@@ -57,7 +61,7 @@ SerializeResult serialize(CssNode node,
   node.accept(visitor);
   var css = visitor._buffer.toString();
   String prefix;
-  if (css.codeUnits.any((codeUnit) => codeUnit > 0x7F)) {
+  if (charset && css.codeUnits.any((codeUnit) => codeUnit > 0x7F)) {
     if (style == OutputStyle.compressed) {
       prefix = '\uFEFF';
     } else {
@@ -910,9 +914,13 @@ class _SerializeVisitor implements CssVisitor, ValueVisitor, SelectorVisitor {
           // doesn't consider them to be valid identifiers.
           !attribute.value.startsWith('--')) {
         _buffer.write(attribute.value);
+
+        if (attribute.modifier != null) _buffer.writeCharCode($space);
       } else {
         _visitQuotedString(attribute.value);
+        if (attribute.modifier != null) _writeOptionalSpace();
       }
+      if (attribute.modifier != null) _buffer.write(attribute.modifier);
     }
     _buffer.writeCharCode($rbracket);
   }

package.json

@@ -4,8 +4,9 @@
     "install dependencies used for testing the Node API."
   ],
   "devDependencies": {
+    "node-sass": "^4.11.0",
     "chokidar": "^2.0.0",
-    "fibers": ">=1.0.0 <4.0.0",
+    "fibers": ">=1.0.0 <5.0.0",
     "intercept-stdout": "^0.1.2"
   }
 }

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.17.3-dev
+version: 1.20.1
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass

test/cli/dart/errors_test.dart

@@ -5,6 +5,7 @@
 @TestOn('vm')
 
 import 'package:test/test.dart';
+import 'package:test_descriptor/test_descriptor.dart' as d;
 
 import '../dart_test.dart';
 import '../shared/errors.dart';
@@ -12,4 +13,21 @@ import '../shared/errors.dart';
 void main() {
   setUpAll(ensureSnapshotUpToDate);
   sharedTests(runSass);
+
+  test("for package urls", () async {
+    await d.file("test.scss", "@import 'package:nope/test';").create();
+
+    var sass = await runSass(["--no-unicode", "test.scss"]);
+    expect(
+        sass.stderr,
+        emitsInOrder([
+          "Error: Can't find stylesheet to import.",
+          "  ,",
+          "1 | @import 'package:nope/test';",
+          "  |         ^^^^^^^^^^^^^^^^^^^",
+          "  '",
+          "  test.scss 1:9  root stylesheet"
+        ]));
+    await sass.shouldExit(65);
+  });
 }

test/cli/dart/update_test.dart

@@ -2,7 +2,8 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-@TestOn('vm')
+// OS X's modification time reporting is flaky, so we skip these tests on it.
+@TestOn('vm && !mac-os')
 
 import 'package:test/test.dart';
 

test/cli/dart/watch_test.dart

@@ -2,7 +2,8 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-@TestOn('vm')
+// OS X's modification time reporting is flaky, so we skip these tests on it.
+@TestOn('vm && !mac-os')
 
 import 'package:test/test.dart';
 

test/cli/node/errors_test.dart

@@ -6,6 +6,7 @@
 @Tags(['node'])
 
 import 'package:test/test.dart';
+import 'package:test_descriptor/test_descriptor.dart' as d;
 
 import '../../ensure_npm_package.dart';
 import '../node_test.dart';
@@ -14,4 +15,21 @@ import '../shared/errors.dart';
 void main() {
   setUpAll(ensureNpmPackage);
   sharedTests(runSass);
+
+  test("for package urls", () async {
+    await d.file("test.scss", "@import 'package:nope/test';").create();
+
+    var sass = await runSass(["--no-unicode", "test.scss"]);
+    expect(
+        sass.stderr,
+        emitsInOrder([
+          "Error: \"package:\" URLs aren't supported on this platform.",
+          "  ,",
+          "1 | @import 'package:nope/test';",
+          "  |         ^^^^^^^^^^^^^^^^^^^",
+          "  '",
+          "  test.scss 1:9  root stylesheet"
+        ]));
+    await sass.shouldExit(65);
+  });
 }

test/cli/node/update_test.dart

@@ -2,7 +2,8 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-@TestOn('vm')
+// OS X's modification time reporting is flaky, so we skip these tests on it.
+@TestOn('vm && !mac-os')
 @Tags(['node'])
 
 import 'package:test/test.dart';

test/cli/node/watch_test.dart

@@ -2,7 +2,8 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-@TestOn('vm')
+// OS X's modification time reporting is flaky, so we skip these tests on it.
+@TestOn('vm && !mac-os')
 @Tags(['node'])
 
 import 'package:test/test.dart';

test/cli/shared.dart

@@ -3,6 +3,7 @@
 // https://opensource.org/licenses/MIT.
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
@@ -389,4 +390,137 @@ void sharedTests(
       await sass.shouldExit(0);
     });
   });
+
+  group("with --charset", () {
+    test("doesn't emit @charset for a pure-ASCII stylesheet", () async {
+      await d.file("test.scss", "a {b: c}").create();
+
+      var sass = await runSass(["test.scss"]);
+      expect(
+          sass.stdout,
+          emitsInOrder([
+            "a {",
+            "  b: c;",
+            "}",
+          ]));
+      await sass.shouldExit(0);
+    });
+
+    test("emits @charset with expanded output", () async {
+      await d.file("test.scss", "a {b: 👭}").create();
+
+      var sass = await runSass(["test.scss"]);
+      expect(
+          sass.stdout,
+          emitsInOrder([
+            "@charset \"UTF-8\";",
+            "a {",
+            "  b: 👭;",
+            "}",
+          ]));
+      await sass.shouldExit(0);
+    });
+
+    test("emits a BOM with compressed output", () async {
+      await d.file("test.scss", "a {b: 👭}").create();
+
+      var sass = await runSass(
+          ["--no-source-map", "--style=compressed", "test.scss", "test.css"]);
+      await sass.shouldExit(0);
+
+      // We can't verify this as a string because `dart:io` automatically trims
+      // the BOM.
+      var bomBytes = utf8.encode("\uFEFF");
+      expect(
+          File(p.join(d.sandbox, "test.css"))
+              .readAsBytesSync()
+              .sublist(0, bomBytes.length),
+          equals(bomBytes));
+    });
+  });
+
+  group("with --no-charset", () {
+    test("doesn't emit @charset with expanded output", () async {
+      await d.file("test.scss", "a {b: 👭}").create();
+
+      var sass = await runSass(["--no-charset", "test.scss"]);
+      expect(
+          sass.stdout,
+          emitsInOrder([
+            "a {",
+            "  b: 👭;",
+            "}",
+          ]));
+      await sass.shouldExit(0);
+    });
+
+    test("doesn't emit a BOM with compressed output", () async {
+      await d.file("test.scss", "a {b: 👭}").create();
+
+      var sass = await runSass([
+        "--no-charset",
+        "--no-source-map",
+        "--style=compressed",
+        "test.scss",
+        "test.css"
+      ]);
+      await sass.shouldExit(0);
+
+      // We can't verify this as a string because `dart:io` automatically trims
+      // the BOM.
+      var bomBytes = utf8.encode("\uFEFF");
+      expect(
+          File(p.join(d.sandbox, "test.css"))
+              .readAsBytesSync()
+              .sublist(0, bomBytes.length),
+          isNot(equals(bomBytes)));
+    });
+  });
+
+  group("with --error-css", () {
+    var message = "Error: Expected expression.";
+    setUp(() => d.file("test.scss", "a {b: 1 + }").create());
+
+    group("not explicitly set", () {
+      test("doesn't emit error CSS when compiling to stdout", () async {
+        var sass = await runSass(["test.scss"]);
+        expect(sass.stdout, emitsDone);
+        await sass.shouldExit(65);
+      });
+
+      test("emits error CSS when compiling to a file", () async {
+        var sass = await runSass(["test.scss", "test.css"]);
+        await sass.shouldExit(65);
+        await d.file("test.css", contains(message)).validate();
+      });
+    });
+
+    group("explicitly set", () {
+      test("emits error CSS when compiling to stdout", () async {
+        var sass = await runSass(["--error-css", "test.scss"]);
+        expect(sass.stdout, emitsThrough(contains(message)));
+        await sass.shouldExit(65);
+      });
+
+      test("emits error CSS when compiling to a file", () async {
+        var sass = await runSass(["--error-css", "test.scss", "test.css"]);
+        await sass.shouldExit(65);
+        await d.file("test.css", contains(message)).validate();
+      });
+    });
+
+    group("explicitly unset", () {
+      test("doesn't emit error CSS when compiling to stdout", () async {
+        var sass = await runSass(["--no-error-css", "test.scss"]);
+        expect(sass.stdout, emitsDone);
+        await sass.shouldExit(65);
+      });
+
+      test("emits error CSS when compiling to a file", () async {
+        var sass = await runSass(["--no-error-css", "test.scss", "test.css"]);
+        await sass.shouldExit(65);
+        await d.nothing("test.css").validate();
+      });
+    });
+  });
 }

test/cli/shared/colon_args.dart

@@ -72,13 +72,14 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
     await d.file("test1.scss", "a {b: }").create();
     await d.file("test2.scss", "x {y: z}").create();
 
+    var message = 'Error: Expected expression.';
     var sass = await runSass(
         ["--no-source-map", "test1.scss:out1.css", "test2.scss:out2.css"]);
-    await expectLater(sass.stderr, emits('Error: Expected expression.'));
+    await expectLater(sass.stderr, emits(message));
     await expectLater(sass.stderr, emitsThrough(contains('test1.scss 1:7')));
     await sass.shouldExit(65);
 
-    await d.nothing("out1.css").validate();
+    await d.file("out1.css", contains(message)).validate();
     await d
         .file("out2.css", equalsIgnoringWhitespace("x { y: z; }"))
         .validate();
@@ -88,18 +89,16 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
     await d.file("test1.scss", "a {b: }").create();
     await d.file("test2.scss", "x {y: z}").create();
 
+    var message = 'Error: Expected expression.';
     var sass = await runSass(
         ["--stop-on-error", "test1.scss:out1.css", "test2.scss:out2.css"]);
     await expectLater(
         sass.stderr,
-        emitsInOrder([
-          'Error: Expected expression.',
-          emitsThrough(contains('test1.scss 1:7')),
-          emitsDone
-        ]));
+        emitsInOrder(
+            [message, emitsThrough(contains('test1.scss 1:7')), emitsDone]));
     await sass.shouldExit(65);
 
-    await d.nothing("out1.css").validate();
+    await d.file("out1.css", contains(message)).validate();
     await d.nothing("out2.css").validate();
   });
 

test/cli/shared/errors.dart

@@ -113,21 +113,4 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
     expect(sass.stderr, emitsThrough(contains("\.dart")));
     await sass.shouldExit(65);
   });
-
-  test("for package urls", () async {
-    await d.file("test.scss", "@import 'package:nope/test';").create();
-
-    var sass = await runSass(["--no-unicode", "test.scss"]);
-    expect(
-        sass.stderr,
-        emitsInOrder([
-          "Error: \"package:\" URLs aren't supported on this platform.",
-          "  ,",
-          "1 | @import 'package:nope/test';",
-          "  |         ^^^^^^^^^^^^^^^^^^^",
-          "  '",
-          "  test.scss 1:9  root stylesheet"
-        ]));
-    await sass.shouldExit(65);
-  });
 }

test/cli/shared/update.dart

@@ -153,12 +153,13 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
     test("with a missing import", () async {
       await d.file("test.scss", "@import 'other'").create();
 
+      var message = "Error: Can't find stylesheet to import.";
       var sass = await update(["test.scss:out.css"]);
-      expect(sass.stderr, emits("Error: Can't find stylesheet to import."));
+      expect(sass.stderr, emits(message));
       expect(sass.stderr, emitsThrough(contains("test.scss 1:9")));
       await sass.shouldExit(65);
 
-      await d.nothing("out.css").validate();
+      await d.file("out.css", contains(message)).validate();
     });
 
     test("with a conflicting import", () async {
@@ -166,29 +167,46 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
       await d.file("other.scss", "a {b: c}").create();
       await d.file("_other.scss", "x {y: z}").create();
 
+      var message = "Error: It's not clear which file to import. Found:";
       var sass = await update(["test.scss:out.css"]);
-      expect(sass.stderr,
-          emits("Error: It's not clear which file to import. Found:"));
+      expect(sass.stderr, emits(message));
       expect(sass.stderr, emitsThrough(contains("test.scss 1:9")));
       await sass.shouldExit(65);
 
-      await d.nothing("out.css").validate();
+      await d.file("out.css", contains(message)).validate();
     });
   });
 
-  group("removes a CSS file", () {
+  group("updates a CSS file", () {
     test("when a file has an error", () async {
       await d.file("test.scss", "a {b: c}").create();
       await (await update(["test.scss:out.css"])).shouldExit(0);
       await d.file("out.css", anything).validate();
 
+      var message = "Error: Expected expression.";
       await d.file("test.scss", "a {b: }").create();
       var sass = await update(["test.scss:out.css"]);
-      expect(sass.stderr, emits("Error: Expected expression."));
+      expect(sass.stderr, emits(message));
       expect(sass.stderr, emitsThrough(contains("test.scss 1:7")));
       await sass.shouldExit(65);
 
-      await d.nothing("out.css").validate();
+      await d.file("out.css", contains(message)).validate();
+    });
+
+    test("when a file has an error even with another stdout output", () async {
+      await d.file("test.scss", "a {b: c}").create();
+      await (await update(["test.scss:out.css"])).shouldExit(0);
+      await d.file("out.css", anything).validate();
+
+      var message = "Error: Expected expression.";
+      await d.file("test.scss", "a {b: }").create();
+      await d.file("other.scss", "x {y: z}").create();
+      var sass = await update(["test.scss:out.css", "other.scss:-"]);
+      expect(sass.stderr, emits(message));
+      expect(sass.stderr, emitsThrough(contains("test.scss 1:7")));
+      await sass.shouldExit(65);
+
+      await d.file("out.css", contains(message)).validate();
     });
 
     test("when an import is removed", () async {
@@ -197,16 +215,32 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
       await (await update(["test.scss:out.css"])).shouldExit(0);
       await d.file("out.css", anything).validate();
 
+      var message = "Error: Can't find stylesheet to import.";
       d.file("_other.scss").io.deleteSync();
       var sass = await update(["test.scss:out.css"]);
-      expect(sass.stderr, emits("Error: Can't find stylesheet to import."));
+      expect(sass.stderr, emits(message));
       expect(sass.stderr, emitsThrough(contains("test.scss 1:9")));
       await sass.shouldExit(65);
 
-      await d.nothing("out.css").validate();
+      await d.file("out.css", contains(message)).validate();
     });
   });
 
+  test("deletes a CSS file when a file has an error with --no-error-css",
+      () async {
+    await d.file("test.scss", "a {b: c}").create();
+    await (await update(["test.scss:out.css"])).shouldExit(0);
+    await d.file("out.css", anything).validate();
+
+    await d.file("test.scss", "a {b: }").create();
+    var sass = await update(["--no-error-css", "test.scss:out.css"]);
+    expect(sass.stderr, emits("Error: Expected expression."));
+    expect(sass.stderr, emitsThrough(contains("test.scss 1:7")));
+    await sass.shouldExit(65);
+
+    await d.nothing("out.css").validate();
+  });
+
   group("doesn't allow", () {
     test("--stdin", () async {
       var sass = await update(["--stdin", "test.scss"]);

test/cli/shared/watch.dart

@@ -65,24 +65,51 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
           await d.file("out.css", "x {y: z}").validate();
         });
 
-        test("continues compiling after an error", () async {
-          await d.file("test1.scss", "a {b: }").create();
-          await d.file("test2.scss", "x {y: z}").create();
+        group("continues compiling after an error", () {
+          test("with --error-css", () async {
+            await d.file("test1.scss", "a {b: }").create();
+            await d.file("test2.scss", "x {y: z}").create();
 
-          var sass =
-              await watch(["test1.scss:out1.css", "test2.scss:out2.css"]);
-          await expectLater(sass.stderr, emits('Error: Expected expression.'));
-          await expectLater(
-              sass.stderr, emitsThrough(contains('test1.scss 1:7')));
-          await expectLater(
-              sass.stdout, emitsThrough('Compiled test2.scss to out2.css.'));
-          await expectLater(sass.stdout, _watchingForChanges);
-          await sass.kill();
+            var message = 'Error: Expected expression.';
+            var sass =
+                await watch(["test1.scss:out1.css", "test2.scss:out2.css"]);
+            await expectLater(sass.stderr, emits(message));
+            await expectLater(
+                sass.stderr, emitsThrough(contains('test1.scss 1:7')));
+            await expectLater(
+                sass.stdout, emitsThrough('Compiled test2.scss to out2.css.'));
+            await expectLater(sass.stdout, _watchingForChanges);
+            await sass.kill();
 
-          await d.nothing("out1.css").validate();
-          await d
-              .file("out2.css", equalsIgnoringWhitespace("x { y: z; }"))
-              .validate();
+            await d.file("out1.css", contains(message)).validate();
+            await d
+                .file("out2.css", equalsIgnoringWhitespace("x { y: z; }"))
+                .validate();
+          });
+
+          test("with --no-error-css", () async {
+            await d.file("test1.scss", "a {b: }").create();
+            await d.file("test2.scss", "x {y: z}").create();
+
+            var sass = await watch([
+              "--no-error-css",
+              "test1.scss:out1.css",
+              "test2.scss:out2.css"
+            ]);
+            await expectLater(
+                sass.stderr, emits('Error: Expected expression.'));
+            await expectLater(
+                sass.stderr, emitsThrough(contains('test1.scss 1:7')));
+            await expectLater(
+                sass.stdout, emitsThrough('Compiled test2.scss to out2.css.'));
+            await expectLater(sass.stdout, _watchingForChanges);
+            await sass.kill();
+
+            await d.nothing("out1.css").validate();
+            await d
+                .file("out2.css", equalsIgnoringWhitespace("x { y: z; }"))
+                .validate();
+          });
         });
 
         test("stops compiling after an error with --stop-on-error", () async {
@@ -94,16 +121,18 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
             "test1.scss:out1.css",
             "test2.scss:out2.css"
           ]);
+
+          var message = 'Error: Expected expression.';
           await expectLater(
               sass.stderr,
               emitsInOrder([
-                'Error: Expected expression.',
+                message,
                 emitsThrough(contains('test1.scss 1:7')),
                 emitsDone
               ]));
           await sass.shouldExit(65);
 
-          await d.nothing("out1.css").validate();
+          await d.file("out1.css", contains(message)).validate();
           await d.nothing("out2.css").validate();
         });
       });
@@ -201,13 +230,14 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
           await expectLater(sass.stdout, _watchingForChanges);
           await tickIfPoll();
 
+          var message = 'Error: Expected expression.';
           await d.file("test.scss", "a {b: }").create();
-          await expectLater(sass.stderr, emits('Error: Expected expression.'));
+          await expectLater(sass.stderr, emits(message));
           await expectLater(
               sass.stderr, emitsThrough(contains('test.scss 1:7')));
           await sass.kill();
 
-          await d.nothing("out.css").validate();
+          await d.file("out.css", contains(message)).validate();
         });
 
         test("stops compiling after an error with --stop-on-error", () async {
@@ -219,21 +249,22 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
           await expectLater(sass.stdout, _watchingForChanges);
           await tickIfPoll();
 
+          var message = 'Error: Expected expression.';
           await d.file("test.scss", "a {b: }").create();
           await expectLater(
               sass.stderr,
               emitsInOrder([
-                'Error: Expected expression.',
+                message,
                 emitsThrough(contains('test.scss 1:7')),
                 emitsDone
               ]));
           await sass.shouldExit(65);
 
-          await d.nothing("out.css").validate();
+          await d.file("out.css", contains(message)).validate();
         });
 
         group("when its dependency is deleted", () {
-          test("and removes the output", () async {
+          test("and updates the output", () async {
             await d.file("_other.scss", "a {b: c}").create();
             await d.file("test.scss", "@import 'other'").create();
 
@@ -243,14 +274,14 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
             await expectLater(sass.stdout, _watchingForChanges);
             await tickIfPoll();
 
+            var message = "Error: Can't find stylesheet to import.";
             d.file("_other.scss").io.deleteSync();
-            await expectLater(
-                sass.stderr, emits("Error: Can't find stylesheet to import."));
+            await expectLater(sass.stderr, emits(message));
             await expectLater(
                 sass.stderr, emitsThrough(contains('test.scss 1:9')));
             await sass.kill();
 
-            await d.nothing("out.css").validate();
+            await d.file("out.css", contains(message)).validate();
           });
 
           test("but another is available", () async {
@@ -374,13 +405,12 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
             await expectLater(sass.stdout, _watchingForChanges);
             await tickIfPoll();
 
+            var message = "Error: It's not clear which file to import. Found:";
             await d.file("_other.sass", "x\n  y: z").create();
-            await expectLater(sass.stderr,
-                emits("Error: It's not clear which file to import. Found:"));
-            await expectLater(sass.stdout, emits("Deleted out.css."));
+            await expectLater(sass.stderr, emits(message));
             await sass.kill();
 
-            await d.nothing("out.css").validate();
+            await d.file("out.css", contains(message)).validate();
           });
 
           group("that overrides the previous dependency", () {

test/compressed_test.dart

@@ -42,6 +42,16 @@ void main() {
               equals("a:nth-child(2n of b,c){x:y}"));
         });
       });
+
+      group("in attribute selectors with modifiers", () {
+        test("removes whitespace when quotes are required", () {
+          expect(_compile('[a=" " b] {x: y}'), equals('[a=" "b]{x:y}'));
+        });
+
+        test("doesn't remove whitespace when quotes aren't required", () {
+          expect(_compile('[a="b"c] {x: y}'), equals('[a=b c]{x:y}'));
+        });
+      });
     });
 
     group("for declarations", () {

test/dart_api_test.dart

@@ -100,6 +100,22 @@ main() {
       expect(css, equals("a {\n  b: 3;\n}"));
     });
 
+    test("can resolve relative paths in a package", () async {
+      await d.dir("subdir", [
+        d.file("test.scss", "@import 'other'"),
+        d.file("_other.scss", "a {b: 1 + 2}"),
+      ]).create();
+
+      await d
+          .file("test.scss", '@import "package:fake_package/test";')
+          .create();
+      var resolver = SyncPackageResolver.config(
+          {"fake_package": p.toUri(d.path('subdir'))});
+
+      var css = compile(d.path("test.scss"), packageResolver: resolver);
+      expect(css, equals("a {\n  b: 3;\n}"));
+    });
+
     test("doesn't import a package URL from a missing package", () async {
       await d
           .file("test.scss", '@import "package:fake_package/test_aux";')
@@ -169,4 +185,44 @@ main() {
       expect(css, equals("a {\n  b: from-importer;\n}"));
     });
   });
+
+  group("charset", () {
+    group("= true", () {
+      test("doesn't emit @charset for a pure-ASCII stylesheet", () {
+        expect(compileString("a {b: c}"), equals("""
+a {
+  b: c;
+}"""));
+      });
+
+      test("emits @charset with expanded output", () async {
+        expect(compileString("a {b: 👭}"), equals("""
+@charset "UTF-8";
+a {
+  b: 👭;
+}"""));
+      });
+
+      test("emits a BOM with compressed output", () async {
+        expect(compileString("a {b: 👭}", style: OutputStyle.compressed),
+            equals("\u{FEFF}a{b:👭}"));
+      });
+    });
+
+    group("= false", () {
+      test("doesn't emit @charset with expanded output", () async {
+        expect(compileString("a {b: 👭}", charset: false), equals("""
+a {
+  b: 👭;
+}"""));
+      });
+
+      test("emits a BOM with compressed output", () async {
+        expect(
+            compileString("a {b: 👭}",
+                charset: false, style: OutputStyle.compressed),
+            equals("a{b:👭}"));
+      });
+    });
+  });
 }

test/node_api/api.dart

@@ -75,6 +75,7 @@ class SassTypes {
   external NodeSassNullClass get Null;
   external Function get Number;
   external Function get String;
+  external Function get Error;
 }
 
 @JS()

test/node_api/function_test.dart

@@ -195,6 +195,16 @@ void main() {
       expect(error.toString(), contains('aw beans'));
     });
 
+    test("reports a synchronous sass.types.Error", () async {
+      var error = await renderError(RenderOptions(
+          data: "a {b: foo()}",
+          functions: jsify({
+            "foo": allowInterop(
+                (_) => callConstructor(sass.types.Error, ["aw beans"]))
+          })));
+      expect(error.toString(), contains('aw beans'));
+    });
+
     test("reports an asynchronous error", () async {
       var error = await renderError(RenderOptions(
           data: "a {b: foo()}",
@@ -208,6 +218,19 @@ void main() {
       expect(error.toString(), contains('aw beans'));
     });
 
+    test("reports an asynchronous sass.types.Error", () async {
+      var error = await renderError(RenderOptions(
+          data: "a {b: foo()}",
+          functions: jsify({
+            "foo": allowInterop((done) {
+              Future.delayed(Duration.zero).then((_) {
+                done(callConstructor(sass.types.Error, ["aw beans"]));
+              });
+            })
+          })));
+      expect(error.toString(), contains('aw beans'));
+    });
+
     test("reports a null return", () async {
       var error = await renderError(RenderOptions(
           data: "a {b: foo()}",

test/output_test.dart

@@ -0,0 +1,26 @@
+// Copyright 2019 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.
+
+// Almost all CSS output tests should go in sass-spec rather than here. This
+// just covers tests that explicitly validate out that's considered too
+// implementation-specific to verify in sass-spec.
+
+import 'package:test/test.dart';
+
+import 'package:sass/sass.dart';
+
+void main() {
+  // Regression test for sass/dart-sass#623. This needs to be tested here
+  // because sass-spec normalizes CR LF newlines.
+  group("normalizes newlines in a loud comment", () {
+    test("in SCSS", () {
+      expect(compileString("/* foo\r\n * bar */"), equals("/* foo\n * bar */"));
+    });
+
+    test("in Sass", () {
+      expect(compileString("/*\r\n  foo\r\n  bar", syntax: Syntax.sass),
+          equals("/* foo\n * bar */"));
+    });
+  });
+}

test/synchronize_test.dart

@@ -2,7 +2,9 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-@TestOn('vm')
+// Windows sees different bytes than other OSes, possibly because of newline
+// normalization issues.
+@TestOn('vm && !windows')
 
 import 'dart:convert';
 import 'dart:io';
@@ -12,17 +14,20 @@ import 'package:test/test.dart';
 
 import '../tool/grind/synchronize.dart' as synchronize;
 
-void main() {
-  test("synchronized files are up-to-date", () {
-    synchronize.sources.forEach((sourcePath, targetPath) {
-      var source = File(sourcePath).readAsStringSync();
-      var target = File(targetPath).readAsStringSync();
+/// The pattern of a checksum in a generated file.
+final _checksumPattern = RegExp(r"^// Checksum: (.*)$", multiLine: true);
 
-      var hash = sha1.convert(utf8.encode(source));
-      if (!target.contains("Checksum: $hash")) {
-        fail("$targetPath is out-of-date.\n"
-            "Run pub run grinder to update it.");
-      }
+void main() {
+  synchronize.sources.forEach((sourcePath, targetPath) {
+    test("synchronized file $targetPath is up-to-date", () {
+      var target = File(targetPath).readAsStringSync();
+      var actualHash = _checksumPattern.firstMatch(target)[1];
+
+      var source = File(sourcePath).readAsBytesSync();
+      var expectedHash = sha1.convert(source).toString();
+      expect(actualHash, equals(expectedHash),
+          reason: "$targetPath is out-of-date.\n"
+              "Run pub run grinder to update it.");
     });
   });
 }

tool/grind.dart

@@ -5,6 +5,7 @@
 import 'package:grinder/grinder.dart';
 
 import 'grind/npm.dart';
+import 'grind/standalone.dart';
 import 'grind/synchronize.dart';
 
 export 'grind/bazel.dart';
@@ -35,5 +36,5 @@ format() {
 npmInstall() => run("npm", arguments: ["install"]);
 
 @Task('Runs the tasks that are required for running tests.')
-@Depends(format, synchronize, npmPackage, npmInstall)
+@Depends(format, synchronize, npmPackage, npmInstall, appSnapshot)
 beforeTest() {}

tool/grind/github.dart

@@ -13,16 +13,14 @@ import 'package:path/path.dart' as p;
 import 'package:pub_semver/pub_semver.dart';
 import 'package:string_scanner/string_scanner.dart';
 
-import '../grind.dart';
+import 'standalone.dart';
 import 'utils.dart';
 
-@Task('Release the current version as to GitHub.')
-@Depends(package)
+@Task('Create a GitHub release for the current version, without executables.')
 githubRelease() async {
   var authorization = _githubAuthorization();
 
-  var client = http.Client();
-  var response = await client.post(
+  var response = await http.post(
       "https://api.github.com/repos/sass/dart-sass/releases",
       headers: {
         "content-type": "application/json",
@@ -40,34 +38,6 @@ githubRelease() async {
   } else {
     log("Released Dart Sass $version to GitHub.");
   }
-
-  var uploadUrl = json
-      .decode(response.body)["upload_url"]
-      // Remove the URL template.
-      .replaceFirst(RegExp(r"\{[^}]+\}$"), "");
-
-  await Future.wait(["linux", "macos", "windows"].expand((os) {
-    return ["ia32", "x64"].map((architecture) async {
-      var format = os == "windows" ? "zip" : "tar.gz";
-      var package = "dart-sass-$version-$os-$architecture.$format";
-      var response = await http.post("$uploadUrl?name=$package",
-          headers: {
-            "content-type":
-                os == "windows" ? "application/zip" : "application/gzip",
-            "authorization": authorization
-          },
-          body: File(p.join("build", package)).readAsBytesSync());
-
-      if (response.statusCode != 201) {
-        fail("${response.statusCode} error uploading $package:\n"
-            "${response.body}");
-      } else {
-        log("Uploaded $package.");
-      }
-    });
-  }));
-
-  client.close();
 }
 
 /// Returns the Markdown-formatted message to use for a GitHub release.
@@ -127,6 +97,52 @@ String _lastChangelogSection() {
   return buffer.toString().trim();
 }
 
+@Task('Release Linux executables to GitHub.')
+@Depends(packageLinux)
+githubLinux() => _uploadExecutables("linux");
+
+@Task('Release Mac OS executables to GitHub.')
+@Depends(packageMacOs)
+githubMacOs() => _uploadExecutables("macos");
+
+@Task('Release Windows executables to GitHub.')
+@Depends(packageWindows)
+githubWindows() => _uploadExecutables("windows");
+
+/// Upload the 32- and 64-bit executables to the current GitHub release
+Future<void> _uploadExecutables(String os) async {
+  var authorization = _githubAuthorization();
+  var client = http.Client();
+  var response = await client.get(
+      "https://api.github.com/repos/sass/dart-sass/releases/tags/$version",
+      headers: {"authorization": authorization});
+
+  var uploadUrl = json
+      .decode(response.body)["upload_url"]
+      // Remove the URL template.
+      .replaceFirst(RegExp(r"\{[^}]+\}$"), "");
+
+  await Future.wait(["ia32", "x64"].map((architecture) async {
+    var format = os == "windows" ? "zip" : "tar.gz";
+    var package = "dart-sass-$version-$os-$architecture.$format";
+    var response = await http.post("$uploadUrl?name=$package",
+        headers: {
+          "content-type":
+              os == "windows" ? "application/zip" : "application/gzip",
+          "authorization": authorization
+        },
+        body: File(p.join("build", package)).readAsBytesSync());
+
+    if (response.statusCode != 201) {
+      fail("${response.statusCode} error uploading $package:\n"
+          "${response.body}");
+    } else {
+      log("Uploaded $package.");
+    }
+  }));
+  await client.close();
+}
+
 /// Returns the HTTP basic authentication Authorization header from the
 /// environment.
 String _githubAuthorization() {

tool/grind/standalone.dart

@@ -47,74 +47,79 @@ void _appSnapshot({@required bool release}) {
       arguments: ['tool/app-snapshot-input.scss'], vmArgs: args, quiet: true);
 }
 
-@Task('Build standalone packages for all OSes.')
+@Task('Build standalone packages for Linux.')
 @Depends(snapshot, releaseAppSnapshot)
-package() async {
+packageLinux() => _buildPackage("linux");
+
+@Task('Build standalone packages for Mac OS.')
+@Depends(snapshot, releaseAppSnapshot)
+packageMacOs() => _buildPackage("macos");
+
+@Task('Build standalone packages for Windows.')
+@Depends(snapshot, releaseAppSnapshot)
+packageWindows() => _buildPackage("windows");
+
+/// Builds standalone 32- and 64-bit Sass packages for the given [os].
+Future _buildPackage(String os) async {
   var client = http.Client();
-  await Future.wait(["linux", "macos", "windows"].expand((os) => [
-        _buildPackage(client, os, x64: true),
-        _buildPackage(client, os, x64: false)
-      ]));
-  client.close();
-}
-
-/// Builds a standalone Sass package for the given [os] and architecture.
-///
-/// The [client] is used to download the corresponding Dart SDK.
-Future _buildPackage(http.Client client, String os, {bool x64 = true}) async {
-  var architecture = x64 ? "x64" : "ia32";
-
-  // TODO: Compile a single executable that embeds the Dart VM and the snapshot
-  // when dart-lang/sdk#27596 is fixed.
-  var channel = isDevSdk ? "dev" : "stable";
-  var url = "https://storage.googleapis.com/dart-archive/channels/$channel/"
-      "release/$dartVersion/sdk/dartsdk-$os-$architecture-release.zip";
-  log("Downloading $url...");
-  var response = await client.get(Uri.parse(url));
-  if (response.statusCode ~/ 100 != 2) {
-    throw "Failed to download package: ${response.statusCode} "
-        "${response.reasonPhrase}.";
-  }
-
-  var dartExecutable = ZipDecoder().decodeBytes(response.bodyBytes).firstWhere(
-      (file) => os == 'windows'
-          ? file.name.endsWith("/bin/dart.exe")
-          : file.name.endsWith("/bin/dart"));
-  var executable = dartExecutable.content as List<int>;
-
-  // Use the app snapshot when packaging for the current operating system.
-  //
-  // TODO: Use an app snapshot everywhere when dart-lang/sdk#28617 is fixed.
-  var snapshot = os == Platform.operatingSystem && x64 == _is64Bit
-      ? "build/sass.dart.app.snapshot"
-      : "build/sass.dart.snapshot";
-
-  var archive = Archive()
-    ..addFile(fileFromBytes(
-        "dart-sass/src/dart${os == 'windows' ? '.exe' : ''}", executable,
-        executable: true))
-    ..addFile(
-        file("dart-sass/src/DART_LICENSE", p.join(sdkDir.path, 'LICENSE')))
-    ..addFile(file("dart-sass/src/sass.dart.snapshot", snapshot))
-    ..addFile(file("dart-sass/src/SASS_LICENSE", "LICENSE"))
-    ..addFile(fileFromString(
-        "dart-sass/dart-sass${os == 'windows' ? '.bat' : ''}",
-        readAndReplaceVersion(
-            "package/dart-sass.${os == 'windows' ? 'bat' : 'sh'}"),
-        executable: true))
-    ..addFile(fileFromString("dart-sass/sass${os == 'windows' ? '.bat' : ''}",
-        readAndReplaceVersion("package/sass.${os == 'windows' ? 'bat' : 'sh'}"),
-        executable: true));
-
-  var prefix = 'build/dart-sass-$version-$os-$architecture';
-  if (os == 'windows') {
-    var output = "$prefix.zip";
-    log("Creating $output...");
-    File(output).writeAsBytesSync(ZipEncoder().encode(archive));
-  } else {
-    var output = "$prefix.tar.gz";
-    log("Creating $output...");
-    File(output)
-        .writeAsBytesSync(GZipEncoder().encode(TarEncoder().encode(archive)));
-  }
+  await Future.wait(["ia32", "x64"].map((architecture) async {
+    // TODO: Compile a single executable that embeds the Dart VM and the
+    // snapshot when dart-lang/sdk#27596 is fixed.
+    var channel = isDevSdk ? "dev" : "stable";
+    var url = "https://storage.googleapis.com/dart-archive/channels/$channel/"
+        "release/$dartVersion/sdk/dartsdk-$os-$architecture-release.zip";
+    log("Downloading $url...");
+    var response = await client.get(Uri.parse(url));
+    if (response.statusCode ~/ 100 != 2) {
+      throw "Failed to download package: ${response.statusCode} "
+          "${response.reasonPhrase}.";
+    }
+
+    var dartExecutable = ZipDecoder()
+        .decodeBytes(response.bodyBytes)
+        .firstWhere((file) => os == 'windows'
+            ? file.name.endsWith("/bin/dart.exe")
+            : file.name.endsWith("/bin/dart"));
+    var executable = dartExecutable.content as List<int>;
+
+    // Use the app snapshot when packaging for the current operating system.
+    //
+    // TODO: Use an app snapshot everywhere when dart-lang/sdk#28617 is fixed.
+    var snapshot =
+        os == Platform.operatingSystem && (architecture == "x64") == _is64Bit
+            ? "build/sass.dart.app.snapshot"
+            : "build/sass.dart.snapshot";
+
+    var archive = Archive()
+      ..addFile(fileFromBytes(
+          "dart-sass/src/dart${os == 'windows' ? '.exe' : ''}", executable,
+          executable: true))
+      ..addFile(
+          file("dart-sass/src/DART_LICENSE", p.join(sdkDir.path, 'LICENSE')))
+      ..addFile(file("dart-sass/src/sass.dart.snapshot", snapshot))
+      ..addFile(file("dart-sass/src/SASS_LICENSE", "LICENSE"))
+      ..addFile(fileFromString(
+          "dart-sass/dart-sass${os == 'windows' ? '.bat' : ''}",
+          readAndReplaceVersion(
+              "package/dart-sass.${os == 'windows' ? 'bat' : 'sh'}"),
+          executable: true))
+      ..addFile(fileFromString(
+          "dart-sass/sass${os == 'windows' ? '.bat' : ''}",
+          readAndReplaceVersion(
+              "package/sass.${os == 'windows' ? 'bat' : 'sh'}"),
+          executable: true));
+
+    var prefix = 'build/dart-sass-$version-$os-$architecture';
+    if (os == 'windows') {
+      var output = "$prefix.zip";
+      log("Creating $output...");
+      File(output).writeAsBytesSync(ZipEncoder().encode(archive));
+    } else {
+      var output = "$prefix.tar.gz";
+      log("Creating $output...");
+      File(output)
+          .writeAsBytesSync(GZipEncoder().encode(TarEncoder().encode(archive)));
+    }
+  }));
+  await client.close();
 }

tool/travis/task/dart_tests.sh

@@ -0,0 +1,7 @@
+#!/bin/bash -e
+# Copyright 2019 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.
+
+echo "$(tput bold)Running Dart tests against Dart $(dart --version &> /dev/stdout).$(tput sgr0)"
+pub run test -p vm -x node

tool/travis/task/node_tests.sh

@@ -0,0 +1,7 @@
+#!/bin/bash -e
+# Copyright 2019 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.
+
+echo "$(tput bold)Running Node tests against Node $(node --version).$(tput sgr0)"
+pub run test -j 2 -t node

tool/travis/task/specs.sh

@@ -0,0 +1,8 @@
+#!/bin/bash -e
+# Copyright 2019 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.
+
+echo "$(tput bold)Running sass-spec against $(dart --version &> /dev/stdout).$(tput sgr0)"
+if [ "$ASYNC" = true ]; then extra_args="--dart-args --async"; fi
+(cd sass-spec; bundle exec sass-spec.rb --dart .. $extra_args)

tool/travis/test.sh

@@ -1,29 +0,0 @@
-#!/bin/bash -e
-# 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.
-
-bold=$(tput bold)
-none=$(tput sgr0)
-
-if [ "$TASK" = analyze ]; then
-  echo "${bold}Analzing Dart code.$none"
-  dartanalyzer --fatal-warnings lib/ test/ tool/
-elif [ "$TASK" = format ]; then
-  echo "${bold}Ensuring Dart code is formatted.$none"
-  ./tool/assert-formatted.sh
-elif [ "$TASK" = tests ]; then
-  if [ -z "$NODE_VERSION" ]; then
-    echo "${bold}Running Dart tests against $(dart --version &> /dev/stdout).$none"
-    pub run test -p vm -x node
-  else
-    echo "${bold}Running Node tests against Node $(node --version).$none"
-    pub run test -j 2 -t node
-  fi;
-else
-  echo "${bold}Running sass-spec against $(dart --version &> /dev/stdout).$none"
-  if [ "$ASYNC" = true ]; then
-    extra_args="--dart-args --async"
-  fi;
-  (cd sass-spec; bundle exec sass-spec.rb --dart .. $extra_args)
-fi

tool/travis/use_dart.sh

@@ -0,0 +1,24 @@
+#!/bin/bash -e
+# Copyright 2019 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.
+
+# A script that installs Dart and runs "pub get" if the current worker isn't
+# using Travis's Dart support.
+
+if [ ! -z "$TRAVIS_DART_VERSION" ]; then exit 0; fi
+
+echo "$(tput bold)Installing Dart $DART_CHANNEL/$DART_VERSION.$(tput sgr0)"
+
+source tool/travis/utils.sh
+
+os="$TRAVIS_OS_NAME"
+if [ "$os" = osx ]; then os=macos; fi
+travis_cmd curl -o dart.zip "https://storage.googleapis.com/dart-archive/channels/$DART_CHANNEL/release/$DART_VERSION/sdk/dartsdk-$os-x64-release.zip"
+travis_cmd unzip dart.zip
+
+export PATH="$PATH:`pwd`/dart-sdk/bin";
+if [ "$os" = windows ]; then echo 'pub.bat "$@"' > `pwd`/dart-sdk/bin/pub; fi
+if [ "$os" = windows ]; then chmod a+x `pwd`/dart-sdk/bin/pub; fi
+
+travis_cmd `pwd`/dart-sdk/bin/pub get