Added debugging information in the testing infrastructure.

tools/testing/dart/test_runner.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Classes and methods for executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 613 matching lines @@
     // so we have to do this check first.
     var stderrLines = new String.fromCharCodes(super.stderr).split("\n");
     for (String line in stderrLines) {
       if (line.contains('Gtk-WARNING **: cannot open display: :99') ||
           line.contains('Failed to run command. return code=1')) {
         // If we get the X server error, or DRT crashes with a core dump, retry
         // the test.
         if ((testCase as BrowserTestCase).numRetries > 0) {
           requestRetry = true;
         }
+        printDebug("Failed because of missing XDisplay");
         return true;
       }
     }
     return false;
   }
 
   bool get _failedBecauseOfUnexpectedDRTOutput {
     /*
      * The output of DumpRenderTree is different for pixel tests than for
      * layout tests.
@@ skipping 22 matching lines @@
         var startOfContentLength = findBytes(stdout, bytesContentLength);
         if (startOfContentLength >= 0) {
           var newLineAfterContentLength = findBytes(stdout,
                                                     bytesNewLine,
                                                     startOfContentLength);
           if (newLineAfterContentLength > 0) {
             var startPosition = newLineAfterContentLength +
                 bytesNewLine.length;
             var endPosition = stdout.length - bytesEOF.length;
 
-            return !areByteArraysEqual(expectedContent,
-                                       0,
-                                       stdout,
-                                       startPosition,
-                                       endPosition - startPosition);
+            var _failed = !areByteArraysEqual(expectedContent,
+                                              0,
+                                              stdout,
+                                              startPosition,
+                                              endPosition - startPosition);
+            if (_failed) {
+              printDebug("Failed because command.expectedOutputFile doesn't "
+                         "match stdout of DRT");
+            }
+            return _failed;
           }
         }
+        printDebug("Failed because we didn't find 'Content-Length' in the DRT "
+                   "output");
         return true;
       } else {
-        return !areByteArraysEqual(expectedContent, 0,
-                                   stdout, 0,
-                                   stdout.length);
+        var _failed = !areByteArraysEqual(expectedContent, 0,
+                                          stdout, 0,
+                                          stdout.length);
+        if (_failed) {
+          printDebug("Failed because command.expectedOutputFile doesn't match "
+                     "stdout of DRT");
+        }
+        return _failed;
       }
     }
+    printDebug("Failed because command.expectedOutputFile doesn't exist");
     return true;
   }
-  
+
   bool get _browserTestFailure {
     // Browser tests fail unless stdout contains
     // 'Content-Type: text/plain' followed by 'PASS'.
     bool has_content_type = false;
     var stdoutLines = new String.fromCharCodes(super.stdout).split("\n");
     for (String line in stdoutLines) {
       switch (line) {
         case 'Content-Type: text/plain':
           has_content_type = true;
           break;
         case 'PASS':
           if (has_content_type) {
-            return (exitCode != 0 && !hasCrashed);
+            var _failed = (exitCode != 0 && !hasCrashed);
+            if (_failed) {
+              printDebug("Failed because '(exitCode != 0 && !hasCrashed) was "
+                         "true");
+            }
+            return _failed;
           }
           break;
       }
     }
+    printDebug("Failed because content-type: text/plain + PASS was not found");
     return true;
   }
+
+  void printDebug(String msg) {
+    print("");
+    print("DEBUG(infrastructure): $msg");
+    print("DEBUG(infrastructure): cmd.executable:  '${command.executable}'");
+    print("DEBUG(infrastructure): cmd.arguments:   '${command.arguments}'");
+    print("DEBUG(infrastructure): cmd.environment: '${command.environment}'");
+    print("");
+  }
 }
 
 // The static analyzer does not actually execute code, so
 // the criteria for success now depend on the text sent
 // to stderr.
 class AnalysisCommandOutputImpl extends CommandOutputImpl {
   // An error line has 8 fields that look like:
   // ERROR|COMPILER|MISSING_SOURCE|file:/tmp/t.dart|15|1|24|Missing source.
   final int ERROR_LEVEL = 0;
   final int ERROR_TYPE = 1;
@@ skipping 1003 matching lines @@
         // the developer doesn't waste his or her time trying to fix a bunch of
         // tests that appear to be broken but were actually just flakes that
         // didn't get retried because there had already been one failure.
         bool allowRetry = _MAX_FAILED_NO_RETRY > _progress.numFailedTests;
         new RunningProcess(test, allowRetry, this).start();
       }
       _numProcesses++;
     }
   }
 }