Change the way Patterns work in scheduled_test/descriptor.

pkg/scheduled_test/lib/src/descriptor/file_descriptor.dart

+// Copyright (c) 2013, 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 descriptor.file;
+
+import 'dart:async';
+import 'dart:io';
+import 'dart:math' as math;
+import 'dart:utf';
+
+import '../../../../../pkg/pathos/lib/path.dart' as path;
+
+import '../../descriptor.dart';
+import '../../scheduled_test.dart';
+import '../utils.dart';
+
+/// A descriptor describing a single file.
+class FileDescriptor extends Descriptor {
+  /// Whether this descriptor describes a binary file. This is only used when
+  /// displaying error messages.
+  final bool isBinary;
+
+  /// The contents of the file, in bytes.
+  final List<int> contents;
+
+  /// The contents of the file as a String. Assumes UTF-8 encoding.
+  String get textContents => new String.fromCharCodes(contents);
+
+  FileDescriptor.binary(String name, List<int> contents)
+      : this._(name, contents, true);
+
+  FileDescriptor(String name, String contents)
+      : this._(name, encodeUtf8(contents), false);
+
+  FileDescriptor._(String name, this.contents, this.isBinary)
+      : super(name);
+
+  Future create([String parent]) => schedule(() {
+    if (parent == null) parent = defaultRoot;
+    return new File(path.join(parent, name)).writeAsBytes(contents);
+  }, "creating file '$name'");
+
+  Future validate([String parent]) =>
+    schedule(() => validateNow(parent), "validating file '$name'");
+
+  Future validateNow([String parent]) {
+    if (parent == null) parent = defaultRoot;
+    var fullPath = path.join(parent, name);
+    if (!new File(fullPath).existsSync()) {
+      throw "File not found: '$fullPath'.";
+    }
+
+    return new File(fullPath).readAsBytes()
+        .then((actualContents) {
+      if (orderedIterableEquals(contents, actualContents)) return;
+      if (isBinary) {
+        // TODO(nweiz): show a hex dump here if the data is small enough.
+        throw "File '$name' didn't contain the expected binary data.";
+      }
+      throw _textMismatchMessage(textContents,
+          new String.fromCharCodes(actualContents));
+    });
+  }
+
+  Stream<List<int>> read() => new Future.immediate(contents).asStream();
+
+  String describe() => name;
+
+  String _textMismatchMessage(String expected, String actual) {
+    final expectedLines = expected.split('\n');
+    final actualLines = actual.split('\n');
+
+    var results = [];
+
+    // Compare them line by line to see which ones match.
+    var length = math.max(expectedLines.length, actualLines.length);
+    for (var i = 0; i < length; i++) {
+      if (i >= actualLines.length) {
+        // Missing output.
+        results.add('? ${expectedLines[i]}');
+      } else if (i >= expectedLines.length) {
+        // Unexpected extra output.
+        results.add('X ${actualLines[i]}');
+      } else {
+        var expectedLine = expectedLines[i];
+        var actualLine = actualLines[i];
+
+        if (expectedLine != actualLine) {
+          // Mismatched lines.
+          results.add('X $actualLine');
+        } else {
+          // Matched lines.
+          results.add('| $actualLine');
+        }
+      }
+    }
+
+    return "File '$name' should contain:\n"
+        "${prefixLines(expected)}\n"
+        "but actually contained:\n"
+        "${results.join('\n')}";
+  }
+}