[BAEL-1935] Synthetic Class in Java (#5122)

* BAEL-1935: Synthetic Class in Java

* Converted tabs to spaces

core-java/src/test/java/com/baeldung/synthetic/SyntheticUnitTest.java

@@ -0,0 +1,99 @@
+package com.baeldung.synthetic;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Unit test for {@link SyntheticFieldDemo}, {@link SyntheticMethodDemo},
+ * {@link SyntheticConstructorDemo} and {@link BridgeMethodDemo} classes.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class SyntheticUnitTest {
+
+    /**
+     * Tests that the {@link SyntheticMethodDemo.NestedClass} contains two synthetic
+     * methods.
+     */
+    @Test
+    public void givenSyntheticMethod_whenIsSinthetic_thenTrue() {
+        // Checks that the nested class contains exactly two synthetic methods.
+        Method[] methods = SyntheticMethodDemo.NestedClass.class.getDeclaredMethods();
+        Assert.assertEquals("This class should contain only two methods", 2, methods.length);
+
+        for (Method m : methods) {
+            System.out.println("Method: " + m.getName() + ", isSynthetic: " + m.isSynthetic());
+            Assert.assertTrue("All the methods of this class should be synthetic", m.isSynthetic());
+        }
+    }
+
+    /**
+     * Tests that {@link SyntheticConstructorDemo.NestedClass} contains a synthetic
+     * constructor.
+     */
+    @Test
+    public void givenSyntheticConstructor_whenIsSinthetic_thenTrue() {
+        // Checks that the nested class contains exactly a synthetic
+        // constructor.
+        int syntheticConstructors = 0;
+        Constructor<?>[] constructors = SyntheticConstructorDemo.NestedClass.class.getDeclaredConstructors();
+        Assert.assertEquals("This class should contain only two constructors", 2, constructors.length);
+
+        for (Constructor<?> c : constructors) {
+            System.out.println("Constructor: " + c.getName() + ", isSynthetic: " + c.isSynthetic());
+
+            // Counts the synthetic constructors.
+            if (c.isSynthetic()) {
+                syntheticConstructors++;
+            }
+        }
+
+        // Checks that there's exactly one synthetic constructor.
+        Assert.assertEquals(1, syntheticConstructors);
+    }
+
+    /**
+     * Tests that {@link SyntheticFieldDemo.NestedClass} contains a synthetic field.
+     */
+    @Test
+    public void givenSyntheticField_whenIsSinthetic_thenTrue() {
+        // This class should contain exactly one synthetic field.
+        Field[] fields = SyntheticFieldDemo.NestedClass.class.getDeclaredFields();
+        Assert.assertEquals("This class should contain only one field", 1, fields.length);
+
+        for (Field f : fields) {
+            System.out.println("Field: " + f.getName() + ", isSynthetic: " + f.isSynthetic());
+            Assert.assertTrue("All the fields of this class should be synthetic", f.isSynthetic());
+        }
+    }
+
+    /**
+     * Tests that {@link BridgeMethodDemo} contains a synthetic bridge method.
+     */
+    @Test
+    public void givenBridgeMethod_whenIsBridge_thenTrue() {
+        // This class should contain exactly one synthetic bridge method.
+        int syntheticMethods = 0;
+        Method[] methods = BridgeMethodDemo.class.getDeclaredMethods();
+        for (Method m : methods) {
+            System.out.println(
+                    "Method: " + m.getName() + ", isSynthetic: " + m.isSynthetic() + ", isBridge: " + m.isBridge());
+
+            // Counts the synthetic methods and checks that they are also bridge
+            // methods.
+            if (m.isSynthetic()) {
+                syntheticMethods++;
+                Assert.assertTrue("The synthetic method in this class should also be a bridge method", m.isBridge());
+            }
+        }
+        
+        // Checks that there's exactly one synthetic bridge method.
+        Assert.assertEquals("There should be exactly 1 synthetic bridge method in this class", 1, syntheticMethods);
+    }
+
+}