Java variable not assigned in JUnit Test Class

Question

I found something strange in my project. I create a test class using JUnit to test my service layer. The service layer itself is not my question. My problem is, I don't know why after I assigned a value to an int variable in my first test method, and then when I try to use that value in the second test method, the variable value is 0

Executed in order because I use @FixMethodOrder(MethodSorters.NAME_ASCENDING)

int id;

@Test
public void firstMethodToTest() {
    id = 10;
    System.out.println(id); // here printed correctly 10
}

@Test
public void secondMethodToTest() {
    System.out.println(id); // here printed 0
}

I also try to change int to Integer but it returns null not 0 anymore. I wonder if in JUnit Test class like this, Java variable acts differently. Thanks.

Yes, I use @SuppressWarnings, @RunWith, @ContextConfiguration and @FixMethodOrder. What could go wrong? :) — Hobas Matius
– Hobas Matius, Commented Dec 29, 2017 at 2:45
jUnit may or may not use the same instance of test to run all test methods: stackoverflow.com/questions/19381352/… Also it is better to make tests independent from each other and from execution order. — Ivan
– Ivan, Commented Dec 29, 2017 at 2:47
Well in my case, the execution order is that important. It should be create at first, update and lastly: remove — Hobas Matius
– Hobas Matius, Commented Dec 29, 2017 at 3:08

Hobas Matius · Accepted Answer · 2017-12-29 03:00:32Z

2

Thanks to @Ivan for giving me a clue to the answer

For each test method (the method annotated with @Test), a new instance of YourTestClass will be created. This is the behavior of Junit.

So, the point is if you want to use a class member for all test methods, just declare the variable as static. In my case: static int id;

answered Dec 29, 2017 at 3:00

Hobas Matius

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2 Comments

Dan Torrey Over a year ago

Great! Can you please mark this as the answer to your question (click the checkbox to make it green)?

Hobas Matius Over a year ago

Yes, I need to wait for 2 days to accept my own answer bro :)

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