For this installment of the Testing in Go series we'll be talking about a grouping of packages that facilitate general-purpose comparisons in various contexts. Since the most common context is testing it seemed like this series was the right place for the discussion.

We generally refer to these comparison functions as assertions (cue ominous background music and spooky sound effects). You may have already read the opinions found on the Golang FAQ related to assertions.

"Why does Go not have assertions?"

Go doesn't provide assertions. They are undeniably convenient, but our experience has been that programmers use them as a crutch to avoid thinking about proper error handling and reporting. Proper error handling means that servers continue operation after non-fatal errors instead of crashing...

"Where is my favorite helper function for testing?"

Go's standard testing package makes it easy to write unit tests, but it lacks features provided in other language's testing frameworks such as assertion functions. An earlier section of this document explained why Go doesn't have assertions, and the same arguments apply to the use of assert in tests.

In general, we agree that in many scenarios a single assertion failure shouldn't prevent a test from running. So, by default the assertion functions we use don't do that. Problem solved.