Remove awful testing hack for testing extensions.

tests/standalone/io/test_extension_test.dart

Index: tests/standalone/io/test_extension_test.dart
diff --git a/tests/standalone/io/test_extension_test.dart b/tests/standalone/io/test_extension_test.dart
index 3f074f9e2de54b2d99077137239b5a792d8fdf97..552a6b334c8e6e600fc0a96f4cb6bb089ccbd631 100644
--- a/tests/standalone/io/test_extension_test.dart
+++ b/tests/standalone/io/test_extension_test.dart
@@ -4,75 +4,60 @@
 //
 // Dart test program for testing native extensions.
 
-#import("dart:io");
-#import("dart:isolate");
+#import('dart:io');
 
-// The following source statements, hidden in a string, fool the test script
-// tools/testing/dart/multitest.dart
-// into copying the files into the generated_tests directory.
-// TODO(3919): Rewrite this test, not as a multitest, to copy them manually.
-const dummyString = '''
-#source('test_extension_tester.dart');
-#source('test_extension.dart');
-''';
-
-void main() {
-  Options options = new Options();
-
-  // Make this a multitest so that the test scripts run a copy of it in
-  // [build directory]/generated_tests.  This way, we can copy the shared
-  // library for test_extension.dart to the test directory.
-  // The "none" case of the multitest, without the following
-  // line, is the one that runs the test of the extension.
-  foo foo foo foo foo; /// 01: compile-time error
-
-  Path testDirectory = new Path.fromNative(options.script).directoryPath;
-  Path buildDirectory = new Path.fromNative(options.executable).directoryPath;
+Future copyFileToDirectory(Path file, Path directory) {
+  String src = file.toNativePath();
+  String dst = directory.toNativePath();
+  switch (Platform.operatingSystem) {
+    case 'linux':
+    case 'macos':
+      return Process.run('cp', [src, dst]);
+    case 'windows':
+      return Process.run('cmd.exe', ['/C', 'copy $src $dst']);
+    default:
+      Expect.fail('Unknown operating system ${Platform.operatingSystem}');
+  }
+}
 
-  // Copy test_extension shared library from the build directory to the
-  // test directory.
-  Future sharedLibraryCopied;
-  // Use the platforms' copy file commands, to preserve executable privilege.
+Path getExtensionPath(Path buildDirectory) {
   switch (Platform.operatingSystem) {
     case 'linux':
-      var source = buildDirectory.append('lib.target/libtest_extension.so');
-      sharedLibraryCopied = Process.run('cp',
-                               [source.toNativePath(),
-                                testDirectory.toNativePath()]);
-      break;
+      return buildDirectory.append('lib.target/libtest_extension.so');
     case 'macos':
-      var source = buildDirectory.append('libtest_extension.dylib');
-      sharedLibraryCopied = Process.run('cp',
-                               [source.toNativePath(),
-                                testDirectory.toNativePath()]);
-      break;
+      return buildDirectory.append('libtest_extension.dylib');
     case 'windows':
-      var source = buildDirectory.append('test_extension.dll');
-      sharedLibraryCopied = Process.run('cmd.exe',
-          ['/C',
-           'copy ${source.toNativePath()} ${testDirectory.toNativePath()}']);
-      break;
+      return buildDirectory.append('test_extension.dll');
     default:
-      Expect.fail("Unknown operating system ${Platform.operatingSystem}");
+      Expect.fail('Unknown operating system ${Platform.operatingSystem}');
   }
+}
 
-  sharedLibraryCopied.handleException((e) {
-    print('Copying of shared library test_extension failed.');
-    throw e;
-  });
-  sharedLibraryCopied.then((ignore) {
-    print('Shared library copied to test directory.');
-    Path copiedTest = testDirectory.append("test_extension_tester.dart");
-    var result = Process.run(options.executable,
-                             [copiedTest.toNativePath()]);
-    result.then((processResult) {
-      print('Output of test_extension_tester.dart:');
-      print('  stdout:');
-      print(processResult.stdout);
-      print('  stderr:');
-      print(processResult.stderr);
-      stdout.flush();
-      exit(processResult.exitCode);
-    });
+void main() {
+  Options options = new Options();
+
+  Path scriptDirectory = new Path.fromNative(options.script).directoryPath;
+  Path buildDirectory = new Path.fromNative(options.executable).directoryPath;
+  Directory tempDirectory = new Directory('').createTempSync();
+  Path testDirectory = new Path.fromNative(tempDirectory.path);
+
+  // Copy test_extension shared library, test_extension.dart and
+  // test_extension_tester.dart to the temporary test directory.
+  copyFileToDirectory(getExtensionPath(buildDirectory),
+                      testDirectory).chain((_) {
+    Path extensionDartFile = scriptDirectory.append('test_extension.dart');
+    return copyFileToDirectory(extensionDartFile, testDirectory);
+  }).chain((_) {
+    Path testExtensionTesterFile =
+        scriptDirectory.append('test_extension_tester.dart');
+    return copyFileToDirectory(testExtensionTesterFile, testDirectory);
+  }).chain((_) {
+    Path script = testDirectory.append('test_extension_tester.dart');
+    return Process.run(options.executable, [script.toNativePath()]);
+  })..then((processResult result) {
+    Expect.equals(0, result.exitCode);
+    tempDirectory.deleteSync(recursive: true);
+  })..handleException((_) {
+    tempDirectory.deleteSync(recursive: true);
   });
 }