Testing is the process of checking the functionality of an application to ensure it runs as per requirements. Unit testing comes into picture at the developers’ level; it is the testing of single entity (class or method). Unit testing plays a critical role in helping a software company deliver quality products to its customers.
Unit testing can be done in two ways − manual testing and automated testing.
What is JUnit ?
JUnit is a unit testing framework for Java programming language. It plays a crucial role test-driven development, and is a family of unit testing frameworks collectively known as xUnit.
JUnit promotes the idea of “first testing then coding”, which emphasizes on setting up the test data for a piece of code that can be tested first and then implemented. This approach is like “test a little, code a little, test a little, code a little.” It increases the productivity of the programmer and the stability of program code, which in turn reduces the stress on the programmer and the time spent on debugging.
What is a Unit Test Case ?
A Unit Test Case is a part of code, which ensures that another part of code (method) works as expected. To achieve the desired results quickly, a test framework is required. JUnit is a perfect unit test framework for Java programming language.
A formal written unit test case is characterized by a known input and an expected output, which is worked out before the test is executed. The known input should test a precondition and the expected output should test a post-condition.
There must be at least two unit test cases for each requirement − one positive test and one negative test. If a requirement has sub-requirements, each sub-requirement must have at least two test cases as positive and negative.
Framework
JUnit is a Regression Testing Framework used by developers to implement unit testing in Java, and accelerate programming speed and increase the quality of code.
Fixtures
Fixtures is a fixed state of a set of objects used as a baseline for running tests. The purpose of a test fixture is to ensure that there is a well-known and fixed environment in which tests are run so that results are repeatable. It includes −
- setUp() method, which runs before every test invocation.
- tearDown() method, which runs after every test method.
Test Suites
A test suite bundles a few unit test cases and runs them together. In JUnit, both @RunWith and @Suite annotation are used to run the suite test.
Test Runners
Test runner is used for executing the test cases.
JUnit Classes
JUnit classes are important classes, used in writing and testing JUnits. Some of the important classes are −
- Assert − Contains a set of assert methods.
- TestCase − Contains a test case that defines the fixture to run multiple tests.
- TestResult − Contains methods to collect the results of executing a test case.
