Added tests for null-key edge cases of IsMapContaining.hasKey() and IsMapContaining.hasEntry()

Author: brownian-motion

hamcrest/src/test/java/org/hamcrest/collection/IsMapContainingKeyTest.java

@@ -4,6 +4,7 @@
 import org.hamcrest.Matcher;
 
 import java.util.HashMap;
+import java.util.Hashtable;
 import java.util.Map;
 import java.util.TreeMap;
 
@@ -62,7 +63,25 @@ public void testMatchesMapContainingKeyWithNumberKeys() throws Exception {
         assertThat(map, hasKey((Number)1));
 
         // TODO: work out the correct sprinkling of wildcards to get this to work!
-//        assertThat(map, hasKey(1));
+        //        assertThat(map, hasKey(1));
+    }
+
+    public void test_mapContainingNullKey_returnsFalse_forMapsWithNonnullKeys() throws Exception {
+        Map<Number, String> map = new Hashtable<>(); // Hashtables cannot store null keys
+        map.put(1, "A");
+        map.put(2, "B");
+
+        assertDoesNotMatch(hasKey((Number)null), map);
+    }
+
+
+    public void test_mapContainingNullKey_returnsTrue_forMapWithNullKey() throws Exception {
+        Map<Number, String> map = new HashMap<>(); // HashMap can store null keys
+        map.put(1, "A");
+        map.put(2, "B");
+        map.put(null, "C");
+
+        assertMatches(hasKey((Number)null), map);
     }
 
     public void testHasReadableDescription() {

hamcrest/src/test/java/org/hamcrest/collection/IsMapContainingTest.java

@@ -4,6 +4,7 @@
 import org.hamcrest.Matcher;
 
 import java.util.HashMap;
+import java.util.Hashtable;
 import java.util.Map;
 import java.util.TreeMap;
 
@@ -46,4 +47,29 @@ public void testDoesNotMatchNull() {
     public void testHasReadableDescription() {
         assertDescription("map containing [\"a\"-><2>]", hasEntry(equalTo("a"), (equalTo(2))));
     }
+
+    public void test_mapContainsEntryWithNullKey_returnsFalseForMapsWithoutNullKeys(){
+        Map<String, Integer> map = new Hashtable<>(); // throws exception if given null key, or if map.containsKey(null) is called
+        map.put("a", 1);
+        map.put("b", 2);
+
+        assertDoesNotMatch(hasEntry(null, 2), map);
+    }
+
+    public void test_mapContainsEntryWithNullKey_returnsTrueForMapWithNullKeyAndMatchingValue(){
+        Map<String, Integer> map = new HashMap<>(); // throws exception if given null key, or if map.containsKey(null) is called
+        map.put("a", 1);
+        map.put("b", 2);
+        map.put(null, 3);
+
+        assertMatches(hasEntry(null, 3), map);
+    }
+
+    public void test_mapContainsEntryWithNullKey_returnsFalseForMapWithNullKeyAndNoMatchingValue(){
+        Map<String, Integer> map = new HashMap<>(); // throws exception if given null key, or if map.containsKey(null) is called
+        map.put("a", 1);
+        map.put("b", 2);
+
+        assertDoesNotMatch(hasEntry(null, 3), map);
+    }
 }