JUnit test with dynamic number of tests

Question

In our project I have several JUnit tests that e.g. take every file from a directory and run a test on it. If I implement a testEveryFileInDirectory method in t

Answer 1

You could consider using JUnitParams library, so you would have a few more (cleaner) options:

@org.junit.runner.RunWith(junitparams.JUnitParamsRunner.class)
public class ParameterizedTest {

    @org.junit.Test
    @junitparams.Parameters(method = "data")
    public void test1(File file) throws Exception {  }

    @org.junit.Test
    @junitparams.Parameters(method = "data")
    public void test2(File file) throws Exception {  }

    public static File[] data() {
        return new File[] { new File("path1"), new File("path2") };
    }
}

---

@org.junit.runner.RunWith(junitparams.JUnitParamsRunner.class)
public class ParameterizedTest {

    @org.junit.Test
    @junitparams.Parameters(value = { "path1", "path2" })
    public void test1(String path) throws Exception {
        File file = new File(path);
    }

    @org.junit.Test
    @junitparams.Parameters(value = { "path1", "path2" })
    public void test2(String path) throws Exception {
        File file = new File(path);
    }
}

---

You can see more samples of usage here.

In addition about JUnitParams, why writting parameterized tests with it is easier and more readable:

JUnitParams project adds a new runner to JUnit and provides much easier and readable parametrised tests for JUnit >=4.6.

Main differences to standard JUnit Parametrised runner:

• more explicit - params are in test method params, not class fields
• less code - you don't need a constructor to set up parameters
• you can mix parametrised with non-parametrised methods in one class
• params can be passed as a CSV string or from a parameters provider class
• parameters provider class can have as many parameters providing methods as you want, so that you can group different cases
• you can have a test method that provides parameters (no external classes or statics anymore)
• you can see actual parameter values in your IDE (in JUnit's Parametrised it's only consecutive numbers of parameters)