Added two string specific matchers

src/dahlia.dart

@@ -2,6 +2,7 @@
 
 #source('matcher/matcher_base.dart');
 #source('matcher/general.dart');
+#source('matcher/string.dart');
 
 #source('structure/expectation.dart');
 #source('structure/block.dart');

src/matcher/string.dart

@@ -0,0 +1,28 @@
+StartWithMatcher startWith(var expected) => new StartWithMatcher(expected);
+ContainSubstringMatcher containSubstring(var expected) => new ContainSubstringMatcher(expected);
+
+class StartWithMatcher implements Matcher {
+  final expected;
+  const StartWithMatcher(this.expected);
+
+  matches(var actual) {
+    return (actual.startsWith(expected));
+  }
+
+  String describeExpectation(var actual) {
+    return 'actual "$actual" to start with the expected "$expected"';
+  }
+}
+
+class ContainSubstringMatcher implements Matcher {
+  final expected;
+  const ContainSubstringMatcher(this.expected);
+
+  matches(var actual) {
+    return (actual.contains(expected));
+  }
+
+  String describeExpectation(var actual) {
+    return 'actual "$actual" to contain the expected "$expected"';
+  }
+}

tests/suites/string_matchers_tests.dart

@@ -0,0 +1,11 @@
+stringMatchersTests() {
+  describe('startWith matcher', () {
+    it('should succeed if the actual string starts with the expected string', () => expect('hallo').to(startWith('ha')));
+    it('should fail if the actual string does not start with the expected string', () => expect('hallo').to(not(startWith('test'))));
+  });
+  describe('containSubstring matcher', () {
+    it('should succeed if the actual string starts with the expected string', () => expect('hallo').to(containSubstring('ha')));
+    it('should succeed if the actual string contains the expected string', () => expect('hallo').to(containSubstring('al')));
+    it('should fail if the actual string does not contain the expected string', () => expect('hallo').to(not(containSubstring('test'))));
+  });
+}

tests/test_suites.dart

@@ -2,12 +2,14 @@
 #import('../src/dahlia.dart');
 
 #source('suites/general_matcher_tests.dart');
+#source('suites/string_matchers_tests.dart');
 #source('suites/block_tests.dart');
 #source('suites/expectation_tests.dart');
 #source('suites/runner_tests.dart');
 
 testSuites() {
   generalMatcherTests();
+  stringMatchersTests();
   blockTests();
   expectationTests();
   runnerTests();