BAEL-2030 remove first element from list (#4803)

core-java-collections/src/test/java/com/baeldung/list/removefirst/RemoveFirstElementUnitTest.java

@@ -0,0 +1,51 @@
+package com.baeldung.list.removefirst;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class RemoveFirstElementUnitTest {
+
+    private List<String> list = new ArrayList<>();
+    private LinkedList<String> linkedList = new LinkedList<>();
+
+    @Before
+    public void init() {
+
+        list.add("cat");
+        list.add("dog");
+        list.add("pig");
+        list.add("cow");
+        list.add("goat");
+
+        linkedList.add("cat");
+        linkedList.add("dog");
+        linkedList.add("pig");
+        linkedList.add("cow");
+        linkedList.add("goat");
+    }
+
+    @Test
+    public void givenList_whenRemoveFirst_thenRemoved() {
+        list.remove(0);
+
+        assertThat(list, hasSize(4));
+        assertThat(list, not(contains("cat")));
+    }
+
+    @Test
+    public void givenLinkedList_whenRemoveFirst_thenRemoved() {
+
+        linkedList.removeFirst();
+
+        assertThat(linkedList, hasSize(4));
+        assertThat(linkedList, not(contains("cat")));
+    }
+
+}