adding test to JSONWriter - testing the hack added in aeaef68

Author: erosb

core/src/test/java/org/everit/json/schema/internal/JSONWriterTest.java

@@ -0,0 +1,43 @@
+package org.everit.json.schema.internal;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.json.JSONString;
+import org.junit.Test;
+
+public class JSONWriterTest {
+
+    public static class Ancestor implements JSONString {
+
+        @Override public String toJSONString() {
+            return null;
+        }
+
+    }
+
+    public static class Descendant extends Ancestor {
+
+    }
+
+    @Test
+    public void classImplementsJSONString() {
+        assertTrue(JSONWriter.implementsJSONString(new Ancestor()));
+    }
+
+    @Test
+    public void subclassImplementsJSONString() {
+        assertTrue(JSONWriter.implementsJSONString(new Descendant()));
+    }
+
+    @Test
+    public void nullDoesNotImplementJSONString() {
+        assertFalse(JSONWriter.implementsJSONString(null));
+    }
+
+    @Test
+    public void objectDoesNotImplementJSONString() {
+        assertFalse(JSONWriter.implementsJSONString(new Object()));
+    }
+
+}