Add test for method mechanisms

Author: mperor

FirstSteps/src/test/java/pl/mperor/lab/java/lang/element/MethodTest.java

@@ -0,0 +1,72 @@
+package pl.mperor.lab.java.lang.element;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+public class MethodTest {
+
+    @Test
+    public void testOverloading() {
+        byte b = 1;
+        Assertions.assertEquals(1, Overloading.countArgs(b), "Type Promotion");
+        Assertions.assertEquals(1, Overloading.countArgs(1.0), "Different Parameter Types");
+        Assertions.assertEquals(2, Overloading.countArgs(1, 'a'), "Different Number of Parameters");
+        Assertions.assertEquals(3, Overloading.countArgs("one", "two", "three"), "Varargs");
+        Assertions.assertEquals(0, Overloading.countArgs(), "Varargs");
+        Assertions.assertEquals(1, new Overloading().countArgs('c'), "Not only static!");
+    }
+
+    static class Overloading {
+        static int countArgs(long l) {
+            return 1;
+        }
+
+        static int countArgs(double d) {
+            return 1;
+        }
+
+        static <T> int countArgs(long l, T t) {
+            return 2;
+        }
+
+        static <T> int countArgs(T... t) {
+            return t != null ? t.length : 0;
+        }
+
+        int countArgs(char c) {
+            return 1;
+        }
+    }
+
+    @Test
+    public void testParameterPassingMechanism() {
+        int primitive = 0;
+        ParameterPassing.primitiveByValue(primitive);
+        Assertions.assertEquals(0, primitive);
+
+        String string = "original";
+        ParameterPassing.immutableObjectByValue(string);
+        Assertions.assertEquals("original", string);
+
+        int[] array = {1, 2, 3};
+        ParameterPassing.mutableObjectByValue(array);
+        Assertions.assertArrayEquals(new int[]{0, 0, 0}, array);
+    }
+
+    static class ParameterPassing {
+        static void primitiveByValue(int primitive) {
+            primitive = 1;
+        }
+
+        static void immutableObjectByValue(String immutable) {
+            immutable = "";
+        }
+
+        static void mutableObjectByValue(int[] array) {
+            Arrays.fill(array, 0);
+        }
+    }
+
+}