Running XCTests in an Xcode Playground
Having recently been introduced to the wonders of Test-Driven Development, starting with RSpec and then Jasmine, I was challenged to port over some UI-less Ruby/JavaScript code, test-driven, into Swift, my weapon of choice. After porting it over successfully into test-driven Swift, I wondered why Xcode didn’t have a simpler way to write just simple, UI-less code with tests, as a full Xcode project can be pretty bulky and overkill for just writing a few tiny unit tests.
Today, I switched my Codewars focus to Swift as Ruby has served me well during my eleven weeks at Makers, but I don’t see it in my future; Swift is where I wanna go. After having started a few kata, I really wanted a way to run these tests locally on my own laptop. So I opened-up a new Playground, pasted the kata’s sample tests in for shits-and-giggles, and to my surprise, Xcode did not complain. Too much. I had to change the last line which runs the suite, but that’s all.
Here’s what works for me:
Line 2: import the XCTest framework so we can actually use it!
Line 4: begin declaring the method we want to test, in this case a very simple addition method that returns an Integer.
Line 8: declare the suite of tests, sub-classing XCTestCase.
Line 9: create a test method that when executed will perform some test actions and most crucially, perform an assertion on the outcome.
Line 10: finally, we run the test suite we’ve just defined.
You should then be presented with the results in your console:
Of course, in the real world, the tests themselves would be in their own source files, and you would most definitely write a failing test first, watch it fail, then write the bare minimum amount of code to make that test pass, then refactor if need be, as per Test-Driven Development. Learn to love seeing red test failures in your console. It’ll make you a better person. Fact.
I had no idea this was possible before today as I haven’t seen an online bootcamp or decent tutorials that cover testing yet, so I kinda just pieced bits together from here and there. Now I know that the XCTest framework is available to Playgrounds, I can go back and morph those full and bulky iOS projects into light-weight Playgrounds where they belong.
Frakkin’ sweet!