Add a --quiet flag to the CLI

Partially addresses #105

CHANGELOG.md

@@ -6,6 +6,8 @@
 * Add a `--load-path` command-line option (alias `-I`) for passing additional
   paths to search for Sass files to import.
 
+* Add a `--quiet` command-line option (alias `-q`) for silencing warnings.
+
 ### Dart API
 
 * Add a `Logger` class that allows users to control how messages are printed by

lib/src/executable.dart

@@ -31,6 +31,7 @@ main(List<String> args) async {
         allowed: ['expanded', 'compressed'],
         defaultsTo: 'expanded')
     ..addFlag('color', abbr: 'c', help: 'Whether to emit terminal colors.')
+    ..addFlag('quiet', abbr: 'q', help: "Don't print warnings.")
     ..addFlag('trace', help: 'Print full Dart stack traces for exceptions.')
     ..addFlag('help',
         abbr: 'h', help: 'Print this usage information.', negatable: false)
@@ -67,6 +68,8 @@ main(List<String> args) async {
 
   var color =
       options.wasParsed('color') ? options['color'] as bool : hasTerminal;
+  var logger =
+      options['quiet'] as bool ? Logger.quiet : new Logger.stderr(color: color);
   var style = options['style'] == 'compressed'
       ? OutputStyle.compressed
       : OutputStyle.expanded;
@@ -76,17 +79,24 @@ main(List<String> args) async {
     String css;
     if (stdinFlag) {
       css = await _compileStdin(
-          style: style, loadPaths: loadPaths, asynchronous: asynchronous);
+          logger: logger,
+          style: style,
+          loadPaths: loadPaths,
+          asynchronous: asynchronous);
     } else {
       var input = options.rest.first;
       if (input == '-') {
         css = await _compileStdin(
-            style: style, loadPaths: loadPaths, asynchronous: asynchronous);
+            logger: logger,
+            style: style,
+            loadPaths: loadPaths,
+            asynchronous: asynchronous);
       } else if (asynchronous) {
         css = await compileAsync(input,
-            color: color, style: style, loadPaths: loadPaths);
+            logger: logger, style: style, loadPaths: loadPaths);
       } else {
-        css = compile(input, color: color, style: style, loadPaths: loadPaths);
+        css =
+            compile(input, logger: logger, style: style, loadPaths: loadPaths);
       }
     }
 
@@ -150,7 +160,7 @@ Future<String> _loadVersion() async {
 
 /// Compiles Sass from standard input and returns the result.
 Future<String> _compileStdin(
-    {bool color: false,
+    {Logger logger,
     OutputStyle style,
     List<String> loadPaths,
     bool asynchronous: false}) async {
@@ -158,10 +168,10 @@ Future<String> _compileStdin(
   var importer = new FilesystemImporter('.');
   if (asynchronous) {
     return await compileStringAsync(text,
-        color: color, style: style, importer: importer, loadPaths: loadPaths);
+        logger: logger, style: style, importer: importer, loadPaths: loadPaths);
   } else {
     return compileString(text,
-        color: color, style: style, importer: importer, loadPaths: loadPaths);
+        logger: logger, style: style, importer: importer, loadPaths: loadPaths);
   }
 }
 

lib/src/logger.dart

@@ -13,6 +13,9 @@ import 'utils.dart';
 ///
 /// This may be implemented by user code.
 abstract class Logger {
+  /// A logger that silently ignores all messages.
+  static final Logger quiet = new _QuietLogger();
+
   /// Creates a logger that prints warnings to standard error, with terminal
   /// colors if [color] is `true` (default `false`).
   const factory Logger.stderr({bool color}) = _StderrLogger;

test/cli_shared.dart

@@ -168,6 +168,40 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
     await sass.shouldExit(0);
   });
 
+  group("with --quiet", () {
+    test("doesn't emit @warn", () async {
+      await d.file("test.scss", "@warn heck").create();
+
+      var sass = await runSass(["--quiet", "test.scss"]);
+      expect(sass.stderr, emitsDone);
+      await sass.shouldExit(0);
+    });
+
+    test("doesn't emit @debug", () async {
+      await d.file("test.scss", "@debug heck").create();
+
+      var sass = await runSass(["--quiet", "test.scss"]);
+      expect(sass.stderr, emitsDone);
+      await sass.shouldExit(0);
+    });
+
+    test("doesn't emit parser warnings", () async {
+      await d.file("test.scss", "a {b: c && d}").create();
+
+      var sass = await runSass(["--quiet", "test.scss"]);
+      expect(sass.stderr, emitsDone);
+      await sass.shouldExit(0);
+    });
+
+    test("doesn't emit runner warnings", () async {
+      await d.file("test.scss", "#{blue} {x: y}").create();
+
+      var sass = await runSass(["--quiet", "test.scss"]);
+      expect(sass.stderr, emitsDone);
+      await sass.shouldExit(0);
+    });
+  });
+
   group("reports errors", () {
     test("from invalid arguments", () async {
       var sass = await runSass(["--asdf"]);