test: custom linked list get before, after

assignment/src/test/java/appointmentplanner/customlist/api/CustomLinkedListTest.java

@@ -7,7 +7,10 @@ import java.util.stream.Stream;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.converter.ConvertWith;
+import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.MethodSources;
 
 import appointmentplanner.StringArrayConverter;
 import appointmentplanner.customlist.CustomLinkedListImpl;
@@ -61,4 +64,42 @@ public class CustomLinkedListTest {
     assertThat(list.contains(toRemove)).isFalse();
   }
 
+  private static enum LlGetPosition {
+    BEFORE, AFTER
+  }
+
+  private static String[] someBasicDataSet = new String[] { "O", "MUJ", "BOZE" };
+
+  private static Stream<Arguments> getAfterBeforeData() {
+    return Stream.of(
+        Arguments.of(someBasicDataSet, LlGetPosition.BEFORE, "MUJ", "O"),
+        Arguments.of(someBasicDataSet, LlGetPosition.AFTER, "MUJ", "BOZE"),
+        Arguments.of(someBasicDataSet, LlGetPosition.AFTER, "BOZE", null),
+        Arguments.of(someBasicDataSet, LlGetPosition.BEFORE, "O", null));
+  }
+
+  @ParameterizedTest
+  @MethodSource("getAfterBeforeData")
+  void cllGetAfter_shouldReturnCorrectResult(String[] data, LlGetPosition position, String reference,
+      String expectedResult) {
+
+    CustomLinkedList<String> list = new CustomLinkedListImpl<>();
+    Stream.of(data).forEach(list::add);
+
+    switch (position) {
+      case BEFORE:
+        assertThat(list.getBefore(reference)).isEqualTo(expectedResult);
+        break;
+
+      case AFTER:
+        assertThat(list.getAfter(reference)).isEqualTo(expectedResult);
+        break;
+
+      default:
+        fail("Incorrect parameters");
+        break;
+    }
+
+  }
+
 }