validate popping & shifting from empty linkedlist (exercism#2332)

p-czigany · web-flow · commit cdb28e9346b3 · 2023-08-28T13:59:32.000+02:00
diff --git a/exercises/practice/linked-list/src/test/java/DoublyLinkedListTest.java b/exercises/practice/linked-list/src/test/java/DoublyLinkedListTest.java
@@ -18,6 +18,17 @@ public void testPushPop() {
         assertThat(list.pop()).isEqualTo(10);
     }
 
+    @Ignore("Remove to run test")
+    @Test
+    public void testPushOncePopTwice() {
+        DoublyLinkedList<Integer> list = new DoublyLinkedList<>();
+
+        list.push(10);
+
+        assertThat(list.pop()).isEqualTo(10);
+        assertThat(list.pop()).isNull();
+    }
+
     @Ignore("Remove to run test")
     @Test
     public void testPushShift() {
@@ -32,6 +43,17 @@ public void testPushShift() {
         assertThat(list.shift()).isEqualTo("30");
     }
 
+    @Ignore("Remove to run test")
+    @Test
+    public void testPushPopShift() {
+        DoublyLinkedList<Integer> list = new DoublyLinkedList<>();
+
+        list.push(10);
+
+        assertThat(list.pop()).isEqualTo(10);
+        assertThat(list.shift()).isNull();
+    }
+
     @Ignore("Remove to run test")
     @Test
     public void testUnshiftShift() {
@@ -46,6 +68,17 @@ public void testUnshiftShift() {
         assertThat(list.shift()).isEqualTo('1');
     }
 
+    @Ignore("Remove to run test")
+    @Test
+    public void testUnshiftOnceShiftTwice() {
+        DoublyLinkedList<String> list = new DoublyLinkedList<>();
+
+        list.unshift("10");
+
+        assertThat(list.shift()).isEqualTo("10");
+        assertThat(list.shift()).isNull();
+    }
+
     @Ignore("Remove to run test")
     @Test
     public void testUnshiftPop() {
@@ -60,6 +93,17 @@ public void testUnshiftPop() {
         assertThat(list.pop()).isEqualTo(30);
     }
 
+    @Ignore("Remove to run test")
+    @Test
+    public void testUnshiftShiftPop() {
+        DoublyLinkedList<Integer> list = new DoublyLinkedList<>();
+
+        list.unshift(10);
+
+        assertThat(list.shift()).isEqualTo(10);
+        assertThat(list.pop()).isNull();
+    }
+
     @Ignore("Remove to run test")
     @Test
     public void testExample() {
