Add ComparatorUtilsTest.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1684262 13f79535-47bb-0310-9956-ffa450edef68

src/test/java/org/apache/commons/collections4/ComparatorUtilsTest.java

@@ -0,0 +1,125 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.collections4;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.util.Comparator;
+
+import org.junit.Test;
+
+/**
+ * Tests ComparatorUtils.
+ *
+ * @version $Id$
+ */
+public class ComparatorUtilsTest {
+
+    @Test
+    public void booleanComparator() {
+        Comparator<Boolean> comp = ComparatorUtils.booleanComparator(true);
+        assertTrue(comp.compare(Boolean.TRUE, Boolean.FALSE) < 0);
+        assertTrue(comp.compare(Boolean.TRUE, Boolean.TRUE) == 0);
+        assertTrue(comp.compare(Boolean.FALSE, Boolean.TRUE) > 0);
+
+        comp = ComparatorUtils.booleanComparator(false);
+        assertTrue(comp.compare(Boolean.TRUE, Boolean.FALSE) > 0);
+        assertTrue(comp.compare(Boolean.TRUE, Boolean.TRUE) == 0);
+        assertTrue(comp.compare(Boolean.FALSE, Boolean.TRUE) < 0);
+    }
+
+    @Test
+    public void chainedComparator() {
+        // simple test: chain 2 natural comparators
+        Comparator<Integer> comp = ComparatorUtils.chainedComparator(ComparatorUtils.<Integer>naturalComparator(),
+                                                                     ComparatorUtils.<Integer>naturalComparator());
+        assertTrue(comp.compare(1, 2) < 0);
+        assertTrue(comp.compare(1, 1) == 0);
+        assertTrue(comp.compare(2, 1) > 0);
+    }
+
+    @Test
+    public void max() {
+        Comparator<Integer> reversed =
+                ComparatorUtils.reversedComparator(ComparatorUtils.<Integer>naturalComparator());
+
+        assertEquals(Integer.valueOf(10), ComparatorUtils.max(1, 10, null));
+        assertEquals(Integer.valueOf(10), ComparatorUtils.max(10, -10, null));
+        
+        assertEquals(Integer.valueOf(1), ComparatorUtils.max(1, 10, reversed));
+        assertEquals(Integer.valueOf(-10), ComparatorUtils.max(10, -10, reversed));
+
+        try {
+            ComparatorUtils.max(1, null, null);
+            fail("expecting NullPointerException");
+        } catch (NullPointerException npe) {
+            // expected
+        }
+
+        try {
+            ComparatorUtils.max(null, 10, null);
+            fail("expecting NullPointerException");
+        } catch (NullPointerException npe) {
+            // expected
+        }
+    }
+
+    @Test
+    public void min() {
+        Comparator<Integer> reversed =
+                ComparatorUtils.reversedComparator(ComparatorUtils.<Integer>naturalComparator());
+
+        assertEquals(Integer.valueOf(1), ComparatorUtils.min(1, 10, null));
+        assertEquals(Integer.valueOf(-10), ComparatorUtils.min(10, -10, null));
+        
+        assertEquals(Integer.valueOf(10), ComparatorUtils.min(1, 10, reversed));
+        assertEquals(Integer.valueOf(10), ComparatorUtils.min(10, -10, reversed));
+
+        try {
+            ComparatorUtils.min(1, null, null);
+            fail("expecting NullPointerException");
+        } catch (NullPointerException npe) {
+            // expected
+        }
+
+        try {
+            ComparatorUtils.min(null, 10, null);
+            fail("expecting NullPointerException");
+        } catch (NullPointerException npe) {
+            // expected
+        }
+    }
+
+    @Test
+    public void nullLowComparator() {
+        Comparator<Integer> comp = ComparatorUtils.nullLowComparator(null);
+        assertTrue(comp.compare(null, 10) < 0);
+        assertTrue(comp.compare(null, null) == 0);
+        assertTrue(comp.compare(10, null) > 0);
+    }
+
+    @Test
+    public void nullHighComparator() {
+        Comparator<Integer> comp = ComparatorUtils.nullHighComparator(null);
+        assertTrue(comp.compare(null, 10) > 0);
+        assertTrue(comp.compare(null, null) == 0);
+        assertTrue(comp.compare(10, null) < 0);
+    }
+
+}