unittest: refactor ahead of matcher changes

test/prints_matcher_test.dart

+// Copyright (c) 2014, 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 matcher.prints_matchers_test;
+
+import 'dart:async';
+
+import 'package:metatest/metatest.dart';
+import 'package:unittest/unittest.dart';
+
+/// The VM and dart2js have different toStrings for closures.
+final closureToString = (() {}).toString();
+
+void main() => initTests(_test);
+
+void _test(message) {
+  initMetatest(message);
+
+  expectTestResults('synchronous', () {
+    test("passes with an expected print", () {
+      expect(() => print("Hello, world!"), prints("Hello, world!\n"));
+    });
+
+    test("combines multiple prints", () {
+      expect(() {
+        print("Hello");
+        print("World!");
+      }, prints("Hello\nWorld!\n"));
+    });
+
+    test("works with a Matcher", () {
+      expect(() => print("Hello, world!"), prints(contains("Hello")));
+    });
+
+    test("describes a failure nicely", () {
+      expect(() => print("Hello, world!"), prints("Goodbye, world!\n"));
+    });
+
+    test("describes a failure with a non-descriptive Matcher nicely", () {
+      expect(() => print("Hello, world!"), prints(contains("Goodbye")));
+    });
+
+    test("describes a failure with no text nicely", () {
+      expect(() {}, prints(contains("Goodbye")));
+    });
+  }, [
+    {'result': 'pass'},
+    {'result': 'pass'},
+    {'result': 'pass'},
+    {
+      'result': 'fail',
+      'message': r'''Expected: prints 'Goodbye, world!\n'
+  ''
+  Actual: <Closure: () => dynamic>
+   Which: printed 'Hello, world!\n'
+  ''
+   Which: is different.
+Expected: Goodbye, w ...
+  Actual: Hello, wor ...
+          ^
+ Differ at offset 0
+'''
+    },
+    {
+      'result': 'fail',
+      'message': r'''Expected: prints contains 'Goodbye'
+  Actual: <Closure: () => dynamic>
+   Which: printed 'Hello, world!\n'
+  ''
+'''
+    },
+    {
+      'result': 'fail',
+      'message': r'''Expected: prints contains 'Goodbye'
+  Actual: <Closure: () => dynamic>
+   Which: printed nothing.
+'''
+    }
+  ]);
+
+  expectTestResults('asynchronous', () {
+    test("passes with an expected print", () {
+      expect(() => new Future(() => print("Hello, world!")),
+          prints("Hello, world!\n"));
+    });
+
+    test("combines multiple prints", () {
+      expect(() => new Future(() {
+        print("Hello");
+        print("World!");
+      }), prints("Hello\nWorld!\n"));
+    });
+
+    test("works with a Matcher", () {
+      expect(() => new Future(() => print("Hello, world!")),
+          prints(contains("Hello")));
+    });
+
+    test("describes a failure nicely", () {
+      expect(() => new Future(() => print("Hello, world!")),
+          prints("Goodbye, world!\n"));
+    });
+
+    test("describes a failure with a non-descriptive Matcher nicely", () {
+      expect(() => new Future(() => print("Hello, world!")),
+          prints(contains("Goodbye")));
+    });
+
+    test("describes a failure with no text nicely", () {
+      expect(() => new Future.value(), prints(contains("Goodbye")));
+    });
+  }, [
+    {'result': 'pass'},
+    {'result': 'pass'},
+    {'result': 'pass'},
+    {
+      'result': 'fail',
+      'message': startsWith(
+          r'''Expected future to complete successfully, but it failed with Expected: 'Goodbye, world!\n'

[nweiz, 2015/01/26 22:44:10]

Long lines.

[kevmoo, 2015/01/27 00:11:30]

These are long string literals. To make it easy to track changes in the printed
output, I'd like to keep them as blocks

+  ''
+  Actual: 'Hello, world!\n'
+  ''
+   Which: is different.
+Expected: Goodbye, w ...
+  Actual: Hello, wor ...
+          ^
+ Differ at offset 0
+''')
+    },
+    {
+      'result': 'fail',
+      'message': startsWith(
+          r'''Expected future to complete successfully, but it failed with Expected: contains 'Goodbye'
+  Actual: 'Hello, world!\n'
+  ''
+''')
+    },
+    {
+      'result': 'fail',
+      'message': startsWith(
+          r'''Expected future to complete successfully, but it failed with Expected: contains 'Goodbye'
+  Actual: ''
+''')
+    }
+  ]);
+}