With this example, we are going to demonstrate users when, how and why JUnit FixMethodOrder annotation is used. In previous example JUnit Hello World, users have seen how they can start using JUnit. Users are advised to see the setup of project in JUnit Hello World example, if they want to continue with Maven.
This example is useful in cases where user wants to run their test cases in particular order. Users are required to have basic knowledge of Java for this example. We will follow with an short example to show the process of using JUnit FixMethodOrder annotation.
You may skip introduction and jump directly to the beginning of the example below.
1. Tools Used
For this example you will need:
- Java 8
- JUnit 4.12
2. Introduction
JUnit @FixMethodOrder annotation is used with JUnit for specifying order of the methods to run. JUnit is a testing framework for Java. Users who are not aware of the JUnit, can refer to the post JUnit Hello World.
By default there is no specific order of execution and the test cases run without any predictability. @FixMethodOrder is useful in instances, where users need to run their test cases in order of the names of the test cases. @FixMethodOrder annotation helps to achieve this goal.
3. JUnit FixMethodOrder Annotation
Furthermore this annotation makes use of MethodSorters Enum as parameter name to identify the order. In order to start with @FixMethodOrder annotation, let’s do a quick look into the MethodSorters Enum.
3.1 MethodSorters Enum
MethodSorters Enum contains 3 types of constants.
- DEFAULT: Default implementation and the order is not predictable.
- JVM: This constant leaves the execution of order on JVM.
- NAME_ASCENDING: This is mostly used constant that sorts the method name in ascending order.
MethodSorters.NAME_ASCENDING is the most noteworthy, and especially relevant for users. It uses Method.toString() method, in case there is a tie breaker (i.e. method with same name) between the method names.
Let’s start with an example.
4. Example
First of all let’s create a class without the @FixMethodOrder annotation. This is a simple class with 3 test cases:
- firstTest()
- secondTest()
- thirdTest()
These are simple test cases which prints out the name of the test case. The output result is also shown after class.
JUnitFixMethodOrderTest
package junit;
import org.junit.Test;
public class JUnitFixMethodOrderTest {
@Test
public void firstTest() {
System.out.println("First Test");
}
@Test
public void thirdTest() {
System.out.println("Third Test");
}
@Test
public void secondTest() {
System.out.println("Second Test");
}
}
The output result is shown below:
Third Test First Test Second Test
Users can see, that the order of execution is not predictable at all, rather test cases run randomly. Now make changes to the class to include the @FixMethodOrder annotation.
See the changes below, especially the highlighted lines.
package junit;
import org.junit.FixMethodOrder;
import org.junit.Test;
import org.junit.runners.MethodSorters;
@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class JUnitFixMethodOrderTest {
@Test
public void firstTest() {
System.out.println("First Test");
}
@Test
public void thirdTest() {
System.out.println("Third Test");
}
@Test
public void secondTest() {
System.out.println("Second Test");
}
}
The output result is shown below:
First Test Second Test Third Test
Hence from the above output, it is clear that the JUnit @FixMethodOrder annotation helps test cases run according to the names of methods.
5. Conclusion
In this example, users have learnt about the use of the JUnit @FixMethodOrder annotation. Users get an insight into how, why and when they should use @FixMethodOrder annotation.
6. Download The Source Code
This was an example of JUnit @FixMethodOrder annotation.
You can download the java file of this example here: JUnitFixMethodOrderTest.zip
