testing - A crust of code

Custom assertions with ExUnit

Any unit testing library makes it easy to build your own custom assertions on top of the base assertions: just write functions. Often, though, you lose important information like appropriate line numbers, output that highlights structure differences, and so on. ExUnit makes it fairly

testing

Code for comparing TDD to Property-Based Testing

Hillel Wayne gave an example problem. The idea, as I understood it, was for people to solve it via property-based testing (PBT) or test-driven design and see what the differences were. In particular, I'm interested whether I missed any bugs that could have been

testing

Tabular tests in Elixir

I recently read Aleksandr Skobelev's nice "Fundamentals of Optimal Code Style." I like that he uses principles of human perception – how the eye tracks things, how humans read – to produce his suggestions for style. And I especially like that he provides justification for my

testing

Where do properties come from?

A not-infrequent response to my skeptical essay on property-based-testing (PBT) is that I left out an important benefit: it makes you think about properties. (I think "invariant" would be a more precise word, but I'll stick with the standard "property".) That response appeals to

testing

Property testing does not inspire (my) confidence

In a post, Hillel Wayne misunderstands my argument about (not necessarily against) property-based testing (PBT). My fault for talking about it on twitter. Here I’ll try to start the discussion I’ve been wanting to have for a long time. Disclaimer: I am

testing

Scannable map or struct assertions

TL;DR: I introduce assert_fields and assert_copy and provide their code. (Updated 2019-12-22 with a new syntax for assert_copy.) I used to say "All the words in a test should be about the purpose of the test." I'll probably be exploring

testing

Chained assertions

TL;DR: Chain assertions for scannability. Here's some code to help. I suspect tests are more often scanned than read. When a test unexpectedly fails, I think people often jump to its source. But they don't read that source sequentially from the top; instead,