Add tests for the ListStack class

app/src/test/java/ch/nuth/zhaw/exbox/ADS1_2_test.java

@@ -0,0 +1,52 @@
+package ch.nuth.zhaw.exbox;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class ADS1_2_test {
+    ListStack stack;
+
+    @BeforeEach
+    public void setUp() {
+        stack = new ListStack();
+    }
+
+    @Test
+    public void testPush1() {
+        stack.push("A");
+        Object o = stack.pop();
+        assertEquals("A", o);
+    }
+
+    @Test
+    public void testPush2() {
+        stack.push("A");
+        stack.push("B");
+        assertEquals("B", stack.pop());
+        assertEquals("A", stack.pop());
+    }
+
+    @Test
+    public void testIsEmpty() {
+        assertTrue(stack.isEmpty());
+        stack.push("A");
+        assertFalse(stack.isEmpty());
+        stack.pop();
+        assertTrue(stack.isEmpty());
+    }
+
+    @Test
+    public void testIsFull() {
+        assertFalse(stack.isFull());
+    }
+
+    @Test
+    public void testEmptyPop() {
+        assertNull(stack.pop());
+    }
+}