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javaunit-testingjunitjunit4
arieljannai
arieljannai

Reputation: 2146

Creating multiple unit tests from a loop in Java

I'm writing unit tests for my (small) program, and the test cases are specified in around 30 different files.
To test it, all I need is a loop that goes over all the files, parse them, and execute what's needed.

The problem is that in that case, all of my tests will be considered as one, since it's all in the same function with the @Test notation.
Is it possible to split it somehow without having to have a separate function for each test file?

The problem with all the tests as one test case, is that I can't see which test case fail the process; and if one fails it fail the rest (I'll get 1 test failed instead of 5/30 failed)

I'm currently using JUnit (4.12), but I'm not obligated to keep using it, so I can switch framework if there's a better solution.

Thanks!

Example:

public class MyTests {
    @Test
    public void testFromFiles {
        // loop through all the files
    }
}

output: 1 test run successfully

Update: The selected answer worked great for me, and I added another solution with JUnit 5 (instead of 4), in case it will help someone.

Upvotes: 1

Views: 6295

Answers (2)

arieljannai
arieljannai

Reputation: 2146

With JUnit 5 and Dynamic Tests:

  • Basic example:

    class DynamicTests {

  @TestFactory
  List<DynamicTest> createSomeTests() {

    return Arrays.asList(
      DynamicTest.dynamicTest("First dynamically created test",
        () -> assertTrue(true)),

      DynamicTest.dynamicTest("Second dynamically created test",
        () -> assertTrue(true))
    );
  }
}

  • Example of getting and filtering all test files:

    class MyTestsClass {
    @TestFactory
    List<DynamicTest> runAllTestFiles() {
        List<DynamicTest> list = new ArrayList<DynamicTest>();
        try (Stream<Path> paths = Files.walk(Paths.get("tests_dir"))) {
            List<Path> files = paths
                    .filter(path -> path.getFileName().toString().endsWith(".mytests"))
                    .collect(Collectors.toList());
            files.forEach(file -> list.add(
                    DynamicTest.dynamicTest(
                        file.getFileName().toString(), 
                        () -> testFileWithSomeAsserts(file))
            ));
        } catch (IOException e) {
            e.printStackTrace();
        }

        return list;
    }
}

The @TestFactory works differently than regular tests, and @BeforeEach / @AfterEach cannot be used in that case:

Dynamic Test Lifecycle

The execution lifecycle of a dynamic test is quite different than it is for a standard @Test case. Specifically, there are no lifecycle callbacks for individual dynamic tests. This means that @BeforeEach and @AfterEach methods and their corresponding extension callbacks are executed for the @TestFactory method but not for each dynamic test. In other words, if you access fields from the test instance within a lambda expression for a dynamic test, those fields will not be reset by callback methods or extensions between the execution of individual dynamic tests generated by the same @TestFactory method.

More examples in the official documentation.

Upvotes: 3

Bor Laze
Bor Laze

Reputation: 2506

Try this way:

@RunWith(Parameterized.class)
public class EdiTest {

    @SuppressWarnings("WeakerAccess")
    @Parameterized.Parameter(value = 0)
    public String model;

    @SuppressWarnings("WeakerAccess")
    @Parameterized.Parameter(value = 1)
    public String filename;

    @Parameterized.Parameters(name = "{index}: testEDI({0}, {1})")
    public static Collection<Object[]> data() {
        return Arrays.asList(new Object[][]{
                {"753", "edi753_A.edi"},
                {"753", "edi753_B.edi"},
                {"754", "edi754.edi"},
                {"810", "edi810-withTax.edi"},
                {"810", "edi810-withoutTax.edi"},
        });
    }

    @Before
    public void setUpContext() throws Exception {
        TestContextManager testContextManager = new TestContextManager(getClass());
        testContextManager.prepareTestInstance(this);
    }

    @Test
    public void testEDI() throws IOException {
        String edi = IOUtils.toString(ClassLoader.getSystemResource(filename));
        EdiConverter driver = ediConverterProvider.getConverter(model);

        // your test code here
    }

}

Upvotes: 6

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