Added unit test for TypeSwitchUtil

Author: SgtSilvio

src/test/java/com/hivemq/client/util/TypeSwitchTest.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2018 dc-square and the HiveMQ MQTT Client Project
+ *
+ * Licensed 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 com.hivemq.client.util;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * @author Silvio Giebl
+ */
+class TypeSwitchTest {
+
+    @Test
+    void never_alwaysSame() {
+        final TypeSwitch<Interface> never1 = TypeSwitch.never();
+        final TypeSwitch<String> never2 = TypeSwitch.never();
+        assertSame(never1, never2);
+    }
+
+    @Test
+    void when_true() {
+        final Interface i = new Impl1();
+        final AtomicInteger counter = new AtomicInteger();
+        TypeSwitch.when(i).is(Impl1.class, impl1 -> counter.incrementAndGet());
+        assertEquals(1, counter.get());
+    }
+
+    @Test
+    void when_false() {
+        final Interface i = new Impl2();
+        final AtomicInteger counter = new AtomicInteger();
+        TypeSwitch.when(i).is(Impl1.class, impl1 -> counter.incrementAndGet());
+        assertEquals(0, counter.get());
+    }
+
+    @Test
+    void when_true_false() {
+        final Interface i = new Impl1();
+        final AtomicInteger counter = new AtomicInteger();
+        TypeSwitch.when(i).is(Impl1.class, impl1 -> counter.incrementAndGet()).is(Impl2.class, impl2 -> fail());
+        assertEquals(1, counter.get());
+    }
+
+    @Test
+    void when_false_true() {
+        final Interface i = new Impl1();
+        final AtomicInteger counter = new AtomicInteger();
+        TypeSwitch.when(i).is(Impl2.class, impl2 -> fail()).is(Impl1.class, impl1 -> counter.incrementAndGet());
+        assertEquals(1, counter.get());
+    }
+
+    private interface Interface {}
+
+    private static class Impl1 implements Interface {}
+
+    private static class Impl2 implements Interface {}
+}