View Source AOC.Case (Advent of Code Utils v4.0.0)

ExUnit.CaseTemplate for writing advent of code test cases.

This template inserts module tags and helper functions into the unit test module. Concretely, it inserts several module tags, which can be used to selectively test certain days using mix test. It also inserts several helpers which make it possible to access the example and puzzle input within the tests.

The use statement expects a year and day option, which are used to generate the correct module tags and helper functions.

Consider using AOC.aoc_test/4 instead of this case template.

Module tags and filtering

This case adds the following module tags:

  • year: the year of the puzzle
  • day: the day of the puzzle
  • aoc: the year and day of the puzzle, separated by a dash, e.g. "1991-8"

mix test allows you to filter tests based on tags, therefore, you can do the following:

  • mix test --only year:1991: will run all tests associated with year 1991.
  • mix test --only day:8: will run all tests associated with day 8.

Specifying multiple --only options combines the options, i.e., running mix test --only day:8 --year:1991 will run all tests of year 1991 and all the tests of any day 8. This is problematic if your solution repository spans multiple years. Therefore, we include the aoc tag, which uniquely identifies a day:

  • mix test --only aoc:1991-8: will run all the tests associated with day 8 of year 1991.

If your solution repository only contains modules for a single year, this behaves identical to mix test --only day:8.


This template injects several helpers into the test module which can be used to access the example and puzzle input. These helpers behave similar to those defined in AOC.IEx, but always fetch the input or example associated with the solution module. The following helpers are injected:

  • example_string/0: Fetch the example input with trailing newlines removed.
  • input_string/0: Fetch the puzzle input, trailing newlines are removed.
  • input_path/0: Get the path to the puzzle input.
  • example_path/0: Get the path to the example input.