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

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

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

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

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,