Question

Suppose that I am intending to draw some user-supplied text on a bitmap in C#, what sort of tests would I write up front?

Is this sort of thing even possible? BDD seems very straight-forward when dealing with mathematical problems but I find it near impossible and more trouble than it’s worth when dealing with custom UI controls, graphics etc.

All of the TDD examples that I can find use simple calculation examples like currency conversion or ten-pin bowling scoring which even a newbie can easily do using TDD. Am I missing something?

Answer 1

Hmm.. I’d like some more specific examples of the behavior you want to test.

AFAIK, BDD is problem-complexity agnostic. If you can explain it to someone in English, you can write a BDD story / scenario.

GIVEN some text entered by the user 'DRAW THIS'
WHEN I have a bitmap 'c:\temp\SampleImage.bmp'
THEN the text should be drawn on the bitmap

Next you map each of the above steps to glue code – that keys into your app code

• some text entered by the user ‘DRAW THIS’ => setText(‘DRAW THIS’)
• I have a bitmap ‘c:\temp\SampleImage.bmp’ => loadBitmap(‘c:\temp\SampleImage.bmp’)
• the text should be drawn on the bitmap => verifyTextOnBitmapInMemory()

The glue code is the developers to define and can be as complex as the situation mandates. Ditto in TDD.