Added walltest, test the getters and setters in the class wall

src/test/java/inf112/skeleton/app/WallTest.java

+package inf112.skeleton.app;
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.*;
+
+public class WallTest{
+	Wall wall;
+	@BeforeEach
+	void setup() {
+		this.wall = new Wall(0, 0, 100, 100, "grass");
+	}
+	
+    @Test
+	void TestgetHeight() {
+	    assertEquals(wall.getHeight(), 100);
+	}
+	@Test
+	void TestgetWidth() {
+		assertEquals(wall.getWidth(), 100);
+	}
+	@Test
+	void TestgetX() {
+		assertEquals(wall.getX(), 0);
+	}
+	@Test
+	void getY() {
+	    assertEquals(wall.getY(), 0);
+	}
+	@Test
+	void getSpeed() {
+		assertEquals(wall.getSpeed(), 0);
+	}
+	@Test
+	void getGravity() {
+	    assertEquals(wall.getGravity(), 0);
+	}
+}