Move isA to ExtraMatchers.isInstance

1 files changed, 39 insertions, 0 deletions

diff --git a/src/test/java/org/zwobble/couscous/tests/util/ExtraMatchers.java b/src/test/java/org/zwobble/couscous/tests/util/ExtraMatchers.java
new file mode 100644
index 0000000..3107d53
--- /dev/null
+++ b/src/test/java/org/zwobble/couscous/tests/util/ExtraMatchers.java
@@ -0,0 +1,39 @@
+package org.zwobble.couscous.tests.util;
+
+import org.hamcrest.Description;
+import org.hamcrest.DiagnosingMatcher;
+import org.hamcrest.Matcher;
+
+public class ExtraMatchers {
+    public static <T, U> Matcher<T> isInstance(Class<U> type, Matcher<? super U> downcastMatcher) {
+        return new DiagnosingMatcher<T>() {
+            @Override
+            protected boolean matches(Object item, Description mismatch) {
+                if (null == item) {
+                    mismatch.appendText("null");
+                    return false;
+                }
+
+                if (!type.isInstance(item)) {
+                    mismatch.appendValue(item).appendText(" is a " + item.getClass().getName());
+                    return false;
+                }
+
+                if (!downcastMatcher.matches(item)) {
+                    downcastMatcher.describeMismatch(item, mismatch);
+                    return false;
+                }
+
+                return true;
+            }
+
+            @Override
+            public void describeTo(Description description) {
+                description
+                    .appendText(type.getSimpleName())
+                    .appendText(" with ");
+                downcastMatcher.describeTo(description);
+            }
+        };
+    }
+}