+1 (315) 557-6473 

Deque Implementation Tests in Java

This Java code provides a suite of JUnit tests for a deque (double-ended queue) implementation. The abstract class, BaseDequeTests, defines tests for size, element retrieval, addition, and removal, ensuring compatibility with both array-based and linked-node-based deque implementations. The tests cover various scenarios, including empty deques, single-element cases, multiple deque interference checks, and operations with different parameterized types. The code emphasizes comprehensive testing, aiming to expose potential bugs through a nuanced test sequence. The final test, confusingTest, challenges the deque's robustness, revealing issues and guiding improvements for array-backed deque implementations.

In-Depth Testing Suite for Java Deque Implementations

This Java code offers a robust suite of JUnit tests for evaluating a deque (double-ended queue) implementation. The abstract class, BaseDequeTests, meticulously examines various scenarios, encompassing size checks, element retrieval, and addition/removal operations. Designed to accommodate both array-based and linked-node-based deque implementations, these tests provide a thorough assessment of the deque's functionality. If you're seeking assistance with your Java assignment, this code serves as a valuable resource for understanding and testing deque implementations, covering critical aspects like interference checks and parameterized type handling. The inclusive and detailed nature of these tests can aid in ensuring the reliability and correctness of your Java assignment involving deque structures.

Block 1. Import Statements

package deques; import edu.washington.cse373.BaseTest; import org.junit.jupiter.api.Test; import java.util.stream.IntStream;
  • This block includes necessary import statements for the test class.
  • BaseTest is a test base class, and Test is from JUnit, a testing framework.
  • IntStream is used later for creating a stream of integers.

Block 2: Class Declaration

public abstract class BaseDequeTests extends BaseTest { protected abstract Deque createDeque(); protected abstract void checkInvariants(Deque deque);
  • This block declares an abstract class BaseDequeTests that extends BaseTest.
  • Abstract methods (createDeque and checkInvariants) need to be implemented by subclasses.

Block 3: Abstract Methods

protected abstract Deque createDeque(); protected abstract void checkInvariants(Deque deque);
  • These abstract methods define the creation of a deque and checking invariants.

Block 4: Test for Size when Empty

@Test void size_whenEmpty_is0() { // ... }
  • This test checks if the size of a newly created deque is 0.
  • Uses assertions from the testing framework.

Block 5: Test for Getting at Index 0 when Empty

@Test void get_at0_whenEmpty_returnsNull() { // ... }
  • This test checks if attempting to get an element at index 0 from an empty deque returns null.

Block 6: Tests for Getting at Negative and Positive Indices when Empty

@Test void get_atNegative_whenEmpty_returnsNull() { // ... } @Test void get_atPositive_whenEmpty_returnsNull() { // ... }
  • Similar to the previous test, but for negative and positive indices.

Block 7: Test for Using Multiple Deques Simultaneously

@Test void usingMultipleDequesSimultaneously_doesNotCauseInterference() { // ... }
  • Checks if using two deques simultaneously does not interfere with each other.

Block 8: Tests for Adding to an Empty Deque

@Test void addTo_empty_doesNotThrow() { // ... } @Test void size_with1Item_is1() { // ... } @Test void get_at0__with1Item_returnsItem() { // ... }
  • Tests the behavior of adding an item to an empty deque.

Block 9: Tests for Removing After Adding 1 Item

@Test void remove_afterAdd1Item_toSameSide_returnsItem() { // ... } @Test void remove_afterAdd1Item_toOppositeSide_returnsItem() { // ... } @Test void remove_whenEmpty_returnsNull() { // ... }
  • Checks the behavior of removing an item after adding one.

Block 10: Tests for Adding and Removing to/from Opposite Ends

@Test void getEach_afterAddToOppositeEnds_returnsCorrectItems() { // ... } @Test void size_afterAddToOppositeEnds_is2() { // ... } @Test void remove_afterAddToOppositeEnds_returnsCorrectItem() { // ... } @Test void size_afterRemove_afterAddToOppositeEnds_is1() { // ... } @Test void remove_afterRemove_afterAddToOppositeEnds_returnsCorrectItem() { // ... }
  • Tests adding many items to the same side and checking if get returns correct items.

Block 11: Tests for Adding Many Items to the Same Side

@Test void getEach_afterAddManyToSameSide_returnsCorrectItems() { // ... }
  • Tests adding many items to the same side and checking if get returns correct items.

Block 12: Tests for Adding and Removing Different Parameterized Types

@Test void remove_afterAddString_returnsCorrectString() { // ... } @Test void remove_afterAddDouble_returnsCorrectDouble() { // ... } @Test void remove_afterAddBoolean_returnsCorrectBoolean() { // ... }
  • Checks if the deque works correctly with different parameterized types.

Block 13. Confusing Test (Multiple Operations)

@Test void confusingTest() { // ... }
  • Demonstrates a test with multiple operations to check the deque's behavior.
  • It involves adding, removing, and checking the correctness of items at different indices.


In conclusion, the BaseDequeTests class serves as a comprehensive suite of tests for generic deque implementations, aiming to validate the correctness and robustness of the deque's behavior. Through a structured series of test cases, it thoroughly examines scenarios such as empty deque states, addition and removal of elements from both ends, handling of various parameterized types, and concurrent usage of multiple deques. By adhering to the principles of unit testing, the suite provides a systematic approach to ensuring the reliability of deque implementations, enabling developers to identify and rectify potential issues. These tests contribute to the overall quality and dependability of deque-based data structures in software systems.