Throw FileSystemException from FileSystemEntity methods.

pkg/front_end/test/memory_file_system_test.dart

 // Copyright (c) 2016, 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.
 // SharedOptions=--supermixin
 
 library front_end.test.memory_file_system_test;
 
 import 'dart:convert';
 import 'dart:io' as io;
 
+import 'package:front_end/file_system.dart' show FileSystemException;
 import 'package:front_end/memory_file_system.dart';
 import 'package:path/path.dart' as pathos;
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MemoryFileSystemTestNative);
     defineReflectiveTests(MemoryFileSystemTestPosix);
     defineReflectiveTests(MemoryFileSystemTestWindows);
     defineReflectiveTests(FileTest);
   });
 }
 
+const Matcher _throwsFileSystemException =
+    const Throws(const isInstanceOf<FileSystemException>());
+
 @reflectiveTest
 class FileTest extends _BaseTestNative {
   String path;
   MemoryFileSystemEntity file;
 
   setUp() {
     super.setUp();
     path = join(tempPath, 'file.txt');
     file = entityForPath(path);
   }
 
   test_equals_differentPaths() {
     expect(file == entityForPath(join(tempPath, 'file2.txt')), isFalse);
   }
 
   test_equals_samePath() {
     expect(file == entityForPath(join(tempPath, 'file.txt')), isTrue);
   }
 
+  test_exists_doesNotExist() async {
+    expect(await file.exists(), false);
+  }
+
+  test_exists_exists() async {
+    file.writeAsStringSync('x');
+    expect(await file.exists(), true);
+  }
+
   test_hashCode_samePath() {
     expect(file.hashCode, entityForPath(join(tempPath, 'file.txt')).hashCode);
   }
 
+  test_lastModified_doesNotExist() async {
+    expect(file.lastModified(), _throwsFileSystemException);
+  }
+
+  test_lastModified_increasesOnEachChange() async {
+    file.writeAsStringSync('x');
+    var mod1 = await file.lastModified();
+    file.writeAsStringSync('y');
+    var mod2 = await file.lastModified();
+    expect(mod2.isAfter(mod1), isTrue);
+
+    var file2 = entityForPath(join(tempPath, 'file2.txt'));
+    file2.writeAsStringSync('z');
+    var mod3 = await file2.lastModified();
+    expect(mod3.isAfter(mod2), isTrue);
+  }
+
   test_path() {
     expect(file.uri, context.toUri(path));
   }
 
   test_readAsBytes_badUtf8() async {
     // A file containing invalid UTF-8 can still be read as raw bytes.
     List<int> bytes = [0xc0, 0x40]; // Invalid UTF-8
     file.writeAsBytesSync(bytes);
     expect(await file.readAsBytes(), bytes);
   }
 
   test_readAsBytes_doesNotExist() {
-    expect(file.readAsBytes(), throwsException);
+    expect(file.readAsBytes(), _throwsFileSystemException);
   }
 
   test_readAsBytes_exists() async {
     var s = 'contents';
     file.writeAsStringSync(s);
     expect(await file.readAsBytes(), UTF8.encode(s));
   }
 
   test_readAsString_badUtf8() {
     file.writeAsBytesSync([0xc0, 0x40]); // Invalid UTF-8
-    expect(file.readAsString(), throwsException);
+    expect(file.readAsString(), _throwsFileSystemException);
   }
 
   test_readAsString_doesNotExist() {
-    expect(file.readAsString(), throwsException);
+    expect(file.readAsString(), _throwsFileSystemException);
   }
 
   test_readAsString_exists() async {
     var s = 'contents';
     file.writeAsStringSync(s);
     expect(await file.readAsString(), s);
   }
 
   test_readAsString_utf8() async {
     file.writeAsBytesSync([0xe2, 0x82, 0xac]); // Unicode € symbol, in UTF-8
     expect(await file.readAsString(), '\u20ac');
   }
 
-  test_exists_doesNotExist() async {
-    expect(await file.exists(), false);
-  }
-
-  test_exists_exists() async {
-    file.writeAsStringSync('x');
-    expect(await file.exists(), true);
-  }
-
-  test_lastModified_doesNotExist() async {
-    expect(file.lastModified(), throwsException);
-  }
-
-  test_lastModified_increasesOnEachChange() async {
-    file.writeAsStringSync('x');
-    var mod1 = await file.lastModified();
-    file.writeAsStringSync('y');
-    var mod2 = await file.lastModified();
-    expect(mod2.isAfter(mod1), isTrue);
-
-    var file2 = entityForPath(join(tempPath, 'file2.txt'));
-    file2.writeAsStringSync('z');
-    var mod3 = await file2.lastModified();
-    expect(mod3.isAfter(mod2), isTrue);
-  }
-
   test_writeAsBytesSync_modifyAfterRead() async {
     file.writeAsBytesSync([1]);
     (await file.readAsBytes())[0] = 2;
     expect(await file.readAsBytes(), [1]);
   }
 
   test_writeAsBytesSync_modifyAfterWrite() async {
     var bytes = [1];
     file.writeAsBytesSync(bytes);
     bytes[0] = 2;
@@ skipping 157 matching lines @@
   String tempPath;
 
   String join(String path1, String path2, [String path3, String path4]) =>
       pathos.windows.join(path1, path2, path3, path4);
 
   void setUp() {
     tempPath = r'c:\test_file_system';
     fileSystem = new MemoryFileSystem(Uri.parse('file:///c:/cwd'));
   }
 }