Better mismatch reporting in IsCollectionContaining

smgfreeman · smgfreeman · commit 599203808f25 · 2009-04-03T11:00:13.000Z
diff --git a/hamcrest-core/src/main/java/org/hamcrest/core/IsCollectionContaining.java b/hamcrest-core/src/main/java/org/hamcrest/core/IsCollectionContaining.java
@@ -9,30 +9,31 @@
 import org.hamcrest.Description;
 import org.hamcrest.Factory;
 import org.hamcrest.Matcher;
-import org.hamcrest.TypeSafeMatcher;
+import org.hamcrest.TypeSafeDiagnosingMatcher;
 
-public class IsCollectionContaining<T> extends TypeSafeMatcher<Iterable<? super T>> {
+public class IsCollectionContaining<T> extends TypeSafeDiagnosingMatcher<Iterable<? super T>> {
     private final Matcher<? super T> elementMatcher;
 
     public IsCollectionContaining(Matcher<? super T> elementMatcher) {
         this.elementMatcher = elementMatcher;
     }
 
     @Override
-    public boolean matchesSafely(Iterable<? super T> collection) {
+    protected boolean matchesSafely(Iterable<? super T> collection, Description mismatchDescription) {
+        boolean isPastFirst = false;
         for (Object item : collection) {
             if (elementMatcher.matches(item)){
                 return true;
             }
+            if (isPastFirst) {
+              mismatchDescription.appendText(", ");
+            }
+            elementMatcher.describeMismatch(item, mismatchDescription);
+            isPastFirst = true;
         }
         return false;
     }
 
-    @Override
-    public void describeMismatchSafely(Iterable<? super T> item, Description mismatchDescription) {
-      mismatchDescription.appendValue(item);
-    }
-    
     public void describeTo(Description description) {
         description
             .appendText("a collection containing ")
@@ -71,4 +72,5 @@ public static <T> Matcher<Iterable<T>> hasItems(T... elements) {
         
         return allOf(all);
     }
+
 }
diff --git a/hamcrest-unit-test/src/main/java/org/hamcrest/collection/IsCollectionContainingTest.java b/hamcrest-unit-test/src/main/java/org/hamcrest/collection/IsCollectionContainingTest.java
@@ -11,7 +11,9 @@
 import java.util.Set;
 
 import org.hamcrest.AbstractMatcherTest;
+import org.hamcrest.Description;
 import org.hamcrest.Matcher;
+import org.hamcrest.TypeSafeDiagnosingMatcher;
 import org.hamcrest.core.IsCollectionContaining;
 import org.hamcrest.core.IsEqual;
 
@@ -29,14 +31,12 @@ public void testMatchesACollectionThatContainsAnElementMatchingTheGivenMatcher()
     }
 
     public void testDoesNotMatchCollectionThatDoesntContainAnElementMatchingTheGivenMatcher() {
-        final Matcher<Iterable<? super String>> matcher1 = hasItem(equalTo("a"));
-        assertDoesNotMatch("should not match list that doesn't contain 'a'",
-                matcher1, asList("b", "c"));
+        final Matcher<Iterable<? super String>> matcher1 = hasItem(mismatchable("a"));
+        assertMismatchDescription("mismatched: b, mismatched: c", matcher1, asList("b", "c"));
         
         
         final Matcher<Iterable<? super String>> matcher2 = hasItem(equalTo("a"));
-        assertDoesNotMatch("should not match the empty list",
-                matcher2, new ArrayList<String>());
+        assertMismatchDescription("", matcher2, new ArrayList<String>());
     }
 
     public void testDoesNotMatchNull() {
@@ -82,5 +82,23 @@ public void testMatchesAllItemsInCollection() {
                 matcher5,
                 asList("e", "c", "b", "d")); // 'a' missing
     }
+    
+    
+    private Matcher<? super String> mismatchable(final String string) {
+      return new TypeSafeDiagnosingMatcher<String>() {
+        @Override
+        protected boolean matchesSafely(String item, Description mismatchDescription) {
+          if (string.equals(item)) 
+            return true;
+          
+          mismatchDescription.appendText("mismatched: " + item);
+          return false;
+        }
+
+        public void describeTo(Description description) {
+          description.appendText("mismatchable: " + string);
+        }
+      };
+    }
 }
 
