JUnit Framework

  • Apply the JUnit framework to unit testing Java code.
  • Define what a unit test is.

In this course, we use a Java library called JUnit to write and run tests.

JUnit provides annotations to write tests using the familiar structure and syntax of Java classes and methods but treats them as "tests" once annotated as one.

The library is included in the lib folder, which we provide as the starter/solution for homework and chapters.

Let's create a test class for the IndexedList ADT:

import org.junit.jupiter.api.Test;

class IndexedListTest {

  @Test
  void put() {
  }

  @Test
  void get() {
  }

  @Test
  void length() {
  }
}

You must store the IndexedListTest.java file inside the folder src/test/java.

Conventionally, a test class has the word "Test" in its name, either preceding or following the class name the tests are written for.

Each method that is annotated with @Test is a unit test.

A "unit test" is a term used in software engineering to refer to a test written to examine the smallest block of code that can be isolated for testing. In most programming languages, such a "unit" is a function/method.

Notice, to use @Test annotation; to use it, you must have the following import at the top of your source code. 

import org.junit.jupiter.api.Test;

IntelliJ is equipped with a plugin that facilitates running JUnit tests. For example, you can click on the green play arrow next to each test to run it.

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