Parametrized Testing With WebDriver and JUnit

12 May

Parametrized testing, with WebDriver and JUnit (4 in this case) is not all that hard, provided you have a few magical incantations, tremendous computing horsepower and endless coffers of disposable funds.

No, really, it’s not that hard! If I can do it, anyone can. The incantations are all you really need (although ample funding, a sturdy laptop and plenty of tasty snacks is always nice).

The first one is this:


This magical JUnit directive goes above the initial class declaration in your code.

The next one is this:

public LoginsParameterizedTest(String uname, String pword, String schoolID, String userType) {
        this.Username = uname;
        this.Password = pword;
        this.SchoolID = schoolID;
        this.UserType = userType;

That’s a constructor for my particular class file. Yours will be different. Just make sure to replace ‘LoginsParameterizedTest’ with whatever the name of your class is, and pass along whatever parameters will be important for your testing. All this constructor does is assign the passed in variables to the actual class variables (each of which should be declared as private beforehand outside of the constructor method).

Now we get to the fun part, the data we’ll be passing to each iteration of the test.

    public static Collection data() {
        return Arrays.asList(
                new Object[][]{
                        { "username1", "password1", "demo", "Instructor" },
                        { "username2", "password2", "demo", "Student" },
                        { "username3", "password3", "demo", "Student" },
                        { "username4", "password4", "demo", "Student" }

You can copy/paste the framework of the code and then tailor your data to match your own test. Just 4 lines here, but there could be as many as you wish. Each element of a given array should map directly to the parameters passed to the constructor. Easy, no?

Finally, for the actual @Test’s, go on as usual, but replace specific parameter data with the parameter variable names you defined earlier in the class, prefixed with ‘this.’ like so:


Those are not the most robust assertions of course, but that’s pretty much all there is to it for the basic approach. For each line of data passed to the constructor, you’ll get a fresh junit test result as output. This can really revolutionize your tests and save you from writing mountains of fragile code. Try taking a simple project you already have under way and parametrizing it.

Next up will be parametrizing values from a spreadsheet or file, instead of from within the code itself.

Huge thanks to Alan Richardson and his absolutely beyond superb WebDriver course on Udemy. Check him out, sign up and let the learning really begin!


One Response to “Parametrized Testing With WebDriver and JUnit”

  1. Scott May 12, 2013 at 3:29 pm #

    Good stuff! I’ve done it from an Excel SS using TestNG, but it was a bear to setup.

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