Change the process API to be completely asynchronous.

tools/testing/dart/test_runner.dart

 // Copyright (c) 2011, 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.
 
 #library("test_runner");
 
 #import("status_file_parser.dart");
 #import("test_progress.dart");
 #import("test_suite.dart");
 
@@ skipping 202 matching lines @@
                  testCase.dynamic.compilerArguments,
                  compilerExitHandler);
     } else {
       runCommand(testCase.executablePath, testCase.arguments, exitHandler);
     }
   }
 
   void runCommand(String executable,
                   List<String> arguments,
                   void exitHandler(int exitCode)) {
-    process = new Process(executable, arguments);
+    process = new Process.start(executable, arguments);
     process.exitHandler = exitHandler;
     startTime = new Date.now();
-    process.start();
     InputStream stdoutStream = process.stdout;
     InputStream stderrStream = process.stderr;
     StringInputStream stdoutStringStream = new StringInputStream(stdoutStream);
     StringInputStream stderrStringStream = new StringInputStream(stderrStream);
     stdoutStringStream.lineHandler =
         makeReadHandler(stdoutStringStream, stdout);
     stderrStringStream.lineHandler =
         makeReadHandler(stderrStringStream, stderr);
     timeoutTimer = new Timer(timeoutHandler, 1000 * testCase.timeout);
   }
@@ skipping 11 matching lines @@
   Process _process;
   StringInputStream _stdoutStream;
   StringInputStream _stderrStream;
 
   TestCase _currentTest;
   StringBuffer _testStdout;
   StringBuffer _testStderr;
   Date _startTime;
   Timer _timer;
 
-  DartcBatchRunnerProcess(String this._executable) {
-    _startProcess();
-  }
+  DartcBatchRunnerProcess(String this._executable);
 
   bool get active() => _currentTest != null;
 
   void startTest(TestCase testCase) {
     _currentTest = testCase;
-    if (testCase.executablePath != _executable) {
-      // Restart this runner with the right executable for this test.
+    if (_process === null) {
+      // Start process if not yet started.
+      _executable = testCase.executablePath;
+      _startProcess(() {
+        doStartTest(testCase);
+      });
+    } else if (testCase.executablePath != _executable) { 
+      // Restart this runner with the right executable for this test
+      // if needed.
       _executable = testCase.executablePath;
       _process.exitHandler = (exitCode) {
         _process.close();
-        _startProcess();
-        doStartTest(testCase);
+        _startProcess(() {
+          doStartTest(testCase);
+        });
       };
       _process.kill();
     } else {
       doStartTest(testCase);
     }
   }
 
   void terminate() {
-    _process.exitHandler = (exitCode) {
-      _process.close();
-    };
-    _process.kill();
+    if (_process !== null) {
+      _process.exitHandler = (exitCode) {
+        _process.close();
+      };
+      _process.kill();
+    }  
   }
 
   void doStartTest(TestCase testCase) {
     _startTime = new Date.now();
     _testStdout = new List<String>();
     _testStderr = new List<String>();
     _stdoutStream.lineHandler = _readOutput(_stdoutStream, _testStdout);
     _stderrStream.lineHandler = _readOutput(_stderrStream, _testStderr);
     _timer = new Timer(_timeoutHandler(testCase), testCase.timeout * 1000);
     _process.stdin.write(_createArgumentsLine(testCase.arguments).charCodes());
@@ skipping 40 matching lines @@
         if (!status.contains("CRASH")) {
           _reportResult(status);
         }
       }
     };
   }
 
   void _exitHandler(exitCode) {
     if (_timer != null) _timer.cancel();
     _process.close();
-    _startProcess();
-    _reportResult(">>> TEST CRASH");
+    _startProcess(() {
+      _reportResult(">>> TEST CRASH");
+    });
   }
 
   void _timeoutHandler(TestCase test) {
     return (ignore) {
       _process.exitHandler = (exitCode) {
         _process.close();
-        _startProcess();
-        _reportResult(">>> TEST TIMEOUT");
+        _startProcess(() {
+          _reportResult(">>> TEST TIMEOUT");  
+        });
       };
       _process.kill();
     };
   }
 
-  void _startProcess() {
-    _process = new Process(_executable, ['-batch']);
+  void _startProcess(then) {
+    _process = new Process.start(_executable, ['-batch']);
     _stdoutStream = new StringInputStream(_process.stdout);
     _stderrStream = new StringInputStream(_process.stderr);
     _testStdout = new List<String>();
     _testStderr = new List<String>();
     _stdoutStream.lineHandler = _readOutput(_stdoutStream, _testStdout);
     _stderrStream.lineHandler = _readOutput(_stderrStream, _testStderr);
     _process.exitHandler = _exitHandler;
-    _process.start();
+    _process.startHandler = then;
   }
 }
 
 
 class ProcessQueue {
   int _numProcesses = 0;
   int _activeTestListers = 0;
   int _maxProcesses;
   bool _verbose;
   Function _enqueueMoreWork;
@@ skipping 86 matching lines @@
       if (test.configuration['component'] == 'dartc') {
         _ensureDartcBatchRunnersStarted(test.executablePath);
         _getDartcBatchRunnerProcess().startTest(test);
       } else {
         new RunningProcess(test).start();
       }
       _numProcesses++;
     }
   }
 }