Welcome to our article, “The Best JUnit Assertion Examples for Your Next Project,” where we’ll dive deep into the realm of JUnit assertion examples. This comprehensive guide is designed to equip you with the knowledge and practical examples you need to harness JUnit’s assertion capabilities effectively.
JUnit assertion examples are the backbone of unit testing, enabling you to assert whether the actual results of your code match the expected outcomes. These assertions not only validate the behavior of your methods but also serve as documentation for your code, helping you and your team understand the intended functionality. Throughout this article The Best JUnit Assertion Examples for Your Next Project, we’ll explore a curated selection of the finest JUnit assertion examples, covering a wide range of scenarios and use cases. Whether you’re a seasoned JUnit user or just starting your journey into unit testing, you’ll find valuable insights and actionable examples that will elevate your testing prowess and enhance the quality of your projects.
By the end of this article, you’ll not only have a firm grasp of the fundamental JUnit assertions but also an extensive repertoire of examples to draw upon in your testing endeavors. You’ll be better equipped to write tests that are not only comprehensive but also maintainable and expressive, setting the stage for the success of your next software project. So, let’s embark on this journey into the world of “JUnit Assertion Examples” and unlock the full potential of JUnit for your development projects.
Table of Contents
JUnit Assertion Examples
JUnit 5 provides a set of assertion methods that allow you to verify the expected outcomes of your test cases. These assertion methods are part of the org.junit.jupiter.api.Assertions class in JUnit 5. Here’s a list of commonly used JUnit 5 assertion methods
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assertEquals(expected, actual)
Check if the expected and actual values are equal. This is often used for comparing objects, primitives, and arrays.
assertEquals(5, result);
assertNotEquals(expected, actual)
Checks if the expected and actual values are not equal.
assertNotEquals(10, result);
assertTrue(condition)
Checks if the given condition is true.
assertTrue(result > 0);
assertFalse(condition)
Checks if the given condition is false.
assertFalse(isEmpty);
assertNull(object)
Checks if the given object is null.
assertNull(object);
assertNotNull(object)
Checks if the given object is not null.
assertNotNull(object);
assertSame(expected, actual)
Checks if the expected and actual references point to the same object.
assertSame(expectedList, actualList);
assertNotSame(expected, actual)
Checks if the expected and actual references do not point to the same object.
assertNotSame(expectedList, actualList);
assertArrayEquals(expectedArray, actualArray)
Checks if the expected and actual arrays are equal in terms of elements and order.
assertArrayEquals(expectedArray, actualArray);
assertIterableEquals(expectedIterable, actualIterable)
Checks if the expected and actual iterables (e.g., collections, lists) contain the same elements in the same order.
assertIterableEquals(expectedList, actualList);
assertThrows(exceptionType, executable)
Checks if executing the specified executable (a lambda or method reference) throws an exception of the specified type.
assertThrows(ArithmeticException.class, () -> divide(10, 0));
assertTimeout(duration, executable)
Checks if executing the specified executable completes within the given duration.
assertTimeout(Duration.ofSeconds(5), () -> performComplexOperation());
assertTimeoutPreemptively(duration, executable)
Similar to assertTimeout, but it runs the executable in a separate thread, allowing it to be preemptively terminated if it exceeds the specified duration.
assertTimeoutPreemptively(Duration.ofSeconds(5), () -> performComplexOperation());
assertAll(executables…)
Allows you to group multiple assertions together and ensures that all of them are executed. Useful for asserting multiple conditions within a single test.
assertAll(
() -> assertEquals(5, result),
() -> assertNotNull(object)
);
