JUnit - parameterized test - multiple constructor calls

Question

I have a list of text files. I can't load them all together, so I constructed a parameterized test, where only some of the files get tested together (test1: file1...file5, test2: file6...file10, ...). The files are loaded in the constructor of the class. The range of files loaded depends on the parameters. I have different test methods in the class (code for describe the problem below).

The problem: The constructor is called separately for every tested method of the class. That means: With 10 methods to test, the constructor is called 10 times for every range of files to test. Consequence: The files are loaded in every test case 10 times via the constructor call.

Any explanation or solution for that problem?

@RunWith(Parameterized.class)   
public class PageListTest {

    private int fileFrom, fileTo;

    @Parameters
    public static Collection<Object[]> data() {
        Object[][] data = new Object[][] {{0, 3}, {22, 24}};
        return Arrays.asList(data);
    }

    public PageListTest(int from, int to) throws Exception {
        fileFrom = from;
        fileTo = to;
        //files are loaded ....
    }

    @Test
    public void testA() {
        //....
    }

    @Test
    public void testB() {
        //....
    }

    //....
}

Thanks in advance.

PS: Of course I could solve the problem by calling all methods to test out of one 'as TEST' declared method. Bur I would like a better solution.

Answer 1

Explanation: that's how JUnit works. There's a new class instance for each test .

Create a static map of file number to file contents. In your constructor, test to see if you've already loaded the file. If not, load it. If yes, skip!