February 1, 2018

...Learn TDD with Codemanship

A Bit of Old School BDD with NUnit & MS Excel

I'm going Old School this morning with my pairing partner, and while she's popped out for a meeting, I thought I'd quickly jot down what we've been working on.

Back in the good old days before BDD/ATDD frameworks, when we wanted to automate customer tests we just captured the customer's example data in something like MS Excel and then wrote a bit of code to read that data into a unit test. (That, essentially, is what SBE tools do, just with some bells and whistles.)

For example, imagine our customer wants to be able to calculate square roots using the software. We could agree an acceptance test, in the trendy hipster "Given...When...Then..." style, and put that in a spreadsheet, like so.

If we name the cell range containing the example data "examples" (for ease of extracting using OLE DB), and save this spreadsheet in the root directory of our Visual Studio test project, then we can relatively easily suck out that data to provide NUnit test cases for a parameterised test with arguments that match the data in the table.

Here's a complete source listing for our basic spike.

(We're going to try and refine this a bit, and see if it can't be made more general. One of the downsides of using a custom TestCaseSource is that we can't parameterise it easily to specify different Excel files and different ranges. Though why such a mechanism doesn't already exist is a bit of a mystery, after 15+ years of NUnit.)

Posted 2 weeks, 5 days ago on February 1, 2018