Run specific tests in Elixir (ExUnit)

28 Apr 2015

When developing Elixir applications, there are two options I’ve learned to use for running my tests in a more specific manner. The normal approach for running tests in a Mix based Elixir project is to simply run:

mix test

This will run all tests, but you can also use this task to only run a specific test file by executing:

mix test test/some_test.exs

You can be even more specific by specifying the line-number of a single task you want to run. Say that you have a test on line 42, then you simply execute:

mix test test/some_test.exs:42

The line number, 42 in the previous example, can be any line number between the line where the wanted test’s test keyword is defined until the next test’s test keyword.