feature: Completed component design pattern implementation, testing and respective README (#2153)

* update the explanation in README.md

* #556 update initial files

* added README to component design pattern

* Rearrange the file

* Finalize the directory

* Add test sample

* Update the title for README.md

* Update the title for README.md

* Update the title for README.md

* Update the title for README.md

* Finish the component design pattern

* Updated comments and docstrings for component DP, added basic tests for App and GameObject java classes. Slight modifications to pom.xml to reflect the test suite introduction.

* updated comments/docstrings for all classes - wrote v1 of README.md for component design pattern.

This still requires the class diagram sketch.

* Update the UML and linked with the README.md

* Update the README.md

* Remove the additional update method and rearrange the file based on the CheckStyle plugin

* Changed the structure based on the code smells feedback from PR

* Documentation update - uml

* Documentation update - grammar

* Updated readme to reflect the use of the LOGGER instead of the system output prints.

* Correct the constant name

* Uses Lombok to remove getter/setter boilerplate

* Rename the constant name

* Branch out from master and finish all the review changes

* Correct the CheckStyle warning

Co-authored-by: Samman Palihapitiya Gamage <u7287889@anu.edu.au>
Co-authored-by: SammanPali <110753804+SammanPali@users.noreply.github.com>

component/src/test/java/com/iluwatar/component/AppTest.java

@@ -0,0 +1,17 @@
+package com.iluwatar.component;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+/**
+ * Tests App class : src/main/java/com/iluwatar/component/App.java
+ * General execution test of the application.
+ */
+class AppTest {
+
+    @Test
+    void shouldExecuteComponentWithoutException() {
+        assertDoesNotThrow(() -> App.main(new String[]{}));
+    }
+}

component/src/test/java/com/iluwatar/component/GameObjectTest.java

@@ -0,0 +1,71 @@
+package com.iluwatar.component;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import java.awt.event.KeyEvent;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Tests GameObject class.
+ * src/main/java/com/iluwatar/component/GameObject.java
+ */
+@Slf4j
+class GameObjectTest {
+    GameObject playerTest;
+    GameObject npcTest;
+    @BeforeEach
+    public void initEach() {
+        //creates player & npc objects for testing
+        //note that velocity and coordinates are initialised to 0 in GameObject.java
+        playerTest = GameObject.createPlayer();
+        npcTest = GameObject.createNpc();
+    }
+
+    /**
+     * Tests the create methods - createPlayer() and createNPC().
+     */
+    @Test
+    void objectTest(){
+        LOGGER.info("objectTest:");
+        assertEquals("player",playerTest.getName());
+        assertEquals("npc",npcTest.getName());
+    }
+
+    /**
+     * Tests the input component with varying key event inputs.
+     * Targets the player game object.
+     */
+    @Test
+    void eventInputTest(){
+        LOGGER.info("eventInputTest:");
+        playerTest.update(KeyEvent.KEY_LOCATION_LEFT);
+        assertEquals(-1, playerTest.getVelocity());
+        assertEquals(-1, playerTest.getCoordinate());
+
+        playerTest.update(KeyEvent.KEY_LOCATION_RIGHT);
+        playerTest.update(KeyEvent.KEY_LOCATION_RIGHT);
+        assertEquals(1, playerTest.getVelocity());
+        assertEquals(0, playerTest.getCoordinate());
+
+        LOGGER.info(Integer.toString(playerTest.getCoordinate()));
+        LOGGER.info(Integer.toString(playerTest.getVelocity()));
+
+        GameObject p2 = GameObject.createPlayer();
+        p2.update(KeyEvent.KEY_LOCATION_LEFT);
+        //in the case of an unknown, object stats are set to default
+        p2.update(KeyEvent.KEY_LOCATION_UNKNOWN);
+        assertEquals(-1, p2.getVelocity());
+    }
+
+    /**
+     * Tests the demo component interface.
+     */
+    @Test
+    void npcDemoTest(){
+        LOGGER.info("npcDemoTest:");
+        npcTest.demoUpdate();
+        assertEquals(2, npcTest.getVelocity());
+        assertEquals(2, npcTest.getCoordinate());
+    }
+}