Add an arguments field to executable settings

See #391

doc/configuration.md

@@ -634,6 +634,18 @@ provide the same settings that can be set using
 [`define_platforms`](#define_platforms), which control how their executables are
 invoked.
 
+#### `arguments`
+
+The `arguments` field provides extra arguments to the executable. It takes a
+string, and parses it in the same way as the POSIX shell:
+
+```yaml
+override_platforms:
+  firefox:
+    settings:
+      arguments: -headless
+```
+
 #### `executable`
 
 The `executable` field tells the test runner where to look for the executable to

lib/src/runner/executable_settings.dart

@@ -4,6 +4,7 @@
 
 import 'dart:io';
 
+import 'package:io/io.dart';
 import 'package:path/path.dart' as p;
 import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
@@ -64,6 +65,22 @@ class ExecutableSettings {
 
   /// Parses settings from a user-provided YAML mapping.
   factory ExecutableSettings.parse(YamlMap settings) {
+    List<String> arguments;
+    var argumentsNode = settings.nodes["arguments"];
+    if (argumentsNode != null) {
+      if (argumentsNode.value is String) {
+        try {
+          arguments = shellSplit(argumentsNode.value);
+        } on FormatException catch (error) {
+          throw new SourceSpanFormatException(
+              error.message, argumentsNode.span);
+        }
+      } else {
+        throw new SourceSpanFormatException(
+            "Must be a string.", argumentsNode.span);
+      }
+    }
+
     String linuxExecutable;
     String macOSExecutable;
     String windowsExecutable;
@@ -88,8 +105,8 @@ class ExecutableSettings {
       }
     }
 
-    // TODO(nweiz): Parse arguments once io#23 is released.
     return new ExecutableSettings(
+        arguments: arguments,
         linuxExecutable: linuxExecutable,
         macOSExecutable: macOSExecutable,
         windowsExecutable: windowsExecutable);

lib/src/runner/node/platform.dart

@@ -170,8 +170,10 @@ class NodePlatform extends PlatformPlugin
 
   /// Starts the Node.js process for [platform] with [jsPath].
   Future<Process> _startProcess(TestPlatform platform, String jsPath) async {
+    var settings = _settings[platform];
     try {
-      return await Process.start(_settings[platform].executable, [jsPath]);
+      return await Process.start(
+          settings.executable, settings.arguments.toList()..add(jsPath));
     } catch (error, stackTrace) {
       await new Future.error(
           new ApplicationException(

pubspec.yaml

@@ -14,6 +14,7 @@ dependencies:
   collection: '^1.8.0'
   glob: '^1.0.0'
   http_multi_server: '>=1.0.0 <3.0.0'
+  io: '^0.3.0'
   js: '^0.6.0'
   meta: '^1.0.0'
   node_preamble: '^1.3.0'

test/runner/configuration/custom_platform_test.dart

@@ -816,6 +816,53 @@ void main() {
                   contains("Failed to run Chrome: $noSuchFileMessage")));
           await test.shouldExit(1);
         });
+
+        test("arguments must be a string", () async {
+          await d.file("dart_test.yaml", """
+            define_platforms:
+              chromium:
+                name: Chromium
+                extends: chrome
+                settings:
+                  arguments: 12
+          """).create();
+
+          var test = await runTest(["-p", "chromium", "test.dart"]);
+          expect(test.stdout, containsInOrder(['Must be a string.', "^^"]));
+          await test.shouldExit(1);
+        });
+
+        test("arguments must be shell parseable", () async {
+          await d.file("dart_test.yaml", """
+            define_platforms:
+              chromium:
+                name: Chromium
+                extends: chrome
+                settings:
+                  arguments: --foo 'bar
+          """).create();
+
+          var test = await runTest(["-p", "chromium", "test.dart"]);
+          expect(test.stdout,
+              containsInOrder(['Unmatched single quote.', "^^^^^^^^^^"]));
+          await test.shouldExit(1);
+        });
+
+        test("with an argument that causes the browser to quit", () async {
+          await d.file("dart_test.yaml", """
+            define_platforms:
+              chromium:
+                name: Chromium
+                extends: chrome
+                settings:
+                  arguments: --version
+          """).create();
+
+          var test = await runTest(["-p", "chromium", "test.dart"]);
+          expect(test.stdout,
+              emitsThrough(contains("Chromium exited before connecting.")));
+          await test.shouldExit(0);
+        }, tags: "chrome");
       });
     });
   });