Surprising lines missing from coverage results

Questions & Help Questions
1

Hey Elixir-land!

It’s been a while since I’ve been around. Getting back into lots of elixir work and I found something unexpected regarding the coverage system. Essentially function calls wrapped in literals don’t seem to get counted as coverable statements.

Steps to reproduce:

  1. run mix new coverage_why
  2. paste in lib/coverage_why.ex
defmodule CoverageWhy do
  def hello do
    :world
  end

  def i_has_coverage do
    hello()
  end

  def i_has_no_coverage do
    {:ok, hello()}
  end

  def i_has_no_coverage_as_well do
    [hello()]
  end

  def i_has_no_coverage_as_either do
    [hello()]

    :ok
  end
end
  1. run mix test --cover

I get the results of

image
image814×531 31.3 KB

Expectations

I would expect all the lines except the original def hello... to be uncovered. If I had to guess the wrapping the call in a literal causes the function call to be inlined somehow. Is this the expected coverage results and is it documented anywhere?