Do not compare the output before we know it has all been written.

tests/standalone/src/StreamPipeTest.dart

Index: tests/standalone/src/StreamPipeTest.dart
diff --git a/tests/standalone/src/StreamPipeTest.dart b/tests/standalone/src/StreamPipeTest.dart
index dfd151659ec8204f2947fc91cb8588d614429c42..c67bc373d1c8145322ca147961d6b4af9dc09732 100644
--- a/tests/standalone/src/StreamPipeTest.dart
+++ b/tests/standalone/src/StreamPipeTest.dart
@@ -96,8 +96,8 @@ class PipeServerGame {
         socketInput.closeHandler = () {
           // Check that the resulting file is equal to the initial
           // file.
-          bool result = compareFileContent(srcFileName, dstFileName);
           fileOutput.closeHandler = () {
+            bool result = compareFileContent(srcFileName, dstFileName);
             new File(dstFileName).deleteSync();
             tempDir.deleteSync();
             Expect.isTrue(result);