Implement runDiff for Windows

Change-Id: Ic9191e3844e5bcd47c97867f4a7cec52c161fd7a
Reviewed-on: https://dart-review.googlesource.com/35280
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Peter von der Ahé <[email protected]>

Author: johnniwinther

pkg/front_end/lib/src/fasta/testing/kernel_chain.dart

@@ -9,7 +9,7 @@ library fasta.testing.kernel_chain;
 
 import 'dart:async' show Future;
 
-import 'dart:io' show Directory, File, IOSink, Platform;
+import 'dart:io' show Directory, File, IOSink;
 
 import 'dart:typed_data' show Uint8List;
 
@@ -275,19 +275,9 @@ class BytesCollector implements Sink<List<int>> {
 }
 
 Future<String> runDiff(Uri expected, String actual) async {
-  if (Platform.isWindows) {
-    // TODO(ahe): Implement this for Windows.
-    return """
-==> Expected ($expected) <==
-${new File.fromUri(expected).readAsStringSync()}
-
-==> Actual <==
-$actual
-
-""";
-  }
-  StdioProcess process = await StdioProcess
-      .run("diff", <String>["-u", expected.toFilePath(), "-"], input: actual);
+  StdioProcess process = await StdioProcess.run(
+      "git", <String>["diff", "--no-index", "-u", expected.toFilePath(), "-"],
+      input: actual, runInShell: true);
   return process.output;
 }
 

pkg/testing/lib/src/stdio_process.dart

@@ -43,8 +43,10 @@ class StdioProcess {
   static Future<StdioProcess> run(String executable, List<String> arguments,
       {String input,
       Duration timeout: const Duration(seconds: 60),
-      bool suppressOutput: true}) async {
-    Process process = await Process.start(executable, arguments);
+      bool suppressOutput: true,
+      bool runInShell: false}) async {
+    Process process =
+        await Process.start(executable, arguments, runInShell: runInShell);
     Timer timer;
     StringBuffer sb = new StringBuffer();
     if (timeout != null) {