TDD for Story 1
Now we have wrote the TA for the first Story, we can start on the TDD.
I create a class call VaadinCalculatorTest

The first thing, we need to verify it’s if press button “2”, it’s what we pressed. It’s quite similar to ourVaadinCalculatorSpec. If we run now, the compilation  work but the test fail. We need to implement the VaadinCalculator so the test run green.

For the readers who don’t use TDD, it’s quite strange to implement only the button “2” and not all the button. But we will by the time we have tested all the button. If we run the current test, now the test, it’s green.

On line 17th and 18th, we have all the properties needed to catch the information needed. Exactly now, the page display nothing. But the event work perfectly.