[BAEL-9547] - Moved 3 articles from guava to guava-collections

guava-collections/src/test/java/org/baeldung/guava/ClassToInstanceMapUnitTest.java

@@ -0,0 +1,70 @@
+package org.baeldung.guava;
+import com.google.common.collect.ClassToInstanceMap;
+import com.google.common.collect.ImmutableClassToInstanceMap;
+import com.google.common.collect.MutableClassToInstanceMap;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class ClassToInstanceMapUnitTest {
+    @Test
+    public void whenOfCalled_thenCreateEmptyImmutableMap() {
+        ClassToInstanceMap<Action> map = ImmutableClassToInstanceMap.of();
+        assertTrue(map.isEmpty());
+    }
+
+    @Test
+    public void whenCreateCalled_thenCreateEmptyMutableMap() {
+        ClassToInstanceMap<Action> map = MutableClassToInstanceMap.create();
+        assertTrue(map.isEmpty());
+    }
+
+    @Test
+    public void whenOfWithParameterCalled_thenCreateSingleEntryMap() {
+        ClassToInstanceMap<Action> map = ImmutableClassToInstanceMap.of(Save.class, new Save());
+        assertEquals(1, map.size());
+    }
+
+    @Test
+    public void whenBuilderUser_thenCreateMap() {
+        ClassToInstanceMap<Action> map = ImmutableClassToInstanceMap.<Action>builder()
+                .put(Save.class, new Save())
+                .put(Open.class, new Open())
+                .build();
+        assertEquals(2, map.size());
+    }
+
+    @Test
+    public void givenClassToInstanceMap_whenGetCalled_returnUpperBoundElement() {
+        ClassToInstanceMap<Action> map = ImmutableClassToInstanceMap.of(Save.class, new Save());
+        Action action = map.get(Save.class);
+        assertTrue(action instanceof Save);
+
+        // Use getInstance to avoid casting
+        Save save = map.getInstance(Save.class);
+    }
+
+    @Test
+    public void givenClassToInstanceMap_whenPutCalled_returnPreviousElementUpperBound() {
+        ClassToInstanceMap<Action> map = MutableClassToInstanceMap.create();
+        map.put(Save.class, new Save());
+        // Put again to get previous value returned
+        Action action = map.put(Save.class, new Save());
+        assertTrue(action instanceof Save);
+
+        // Use putInstance to avoid casting
+        Save save = map.putInstance(Save.class, new Save());
+    }
+}
+
+abstract class Action {
+}
+
+class Save extends Action {
+}
+
+class Open extends Action {
+}
+
+class Delete extends Action {
+}