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Power Assert

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Power Assert makes test results easier to understand, without changing your ExUnit test code.

Demo

Example test is here:

test "Enum.at should return the element at the given index" do
  array = [1, 2, 3, 4, 5, 6]; index = 2; two = 2
  assert array |> Enum.at(index) == two
end

Here is the difference between ExUnit and Power Assert results:

Difference between ExUnit and Power Assert

Enjoy :muscle: !

Installation

Add Power Assert to your mix.exs dependencies:

defp deps do
  [{:power_assert, "~> 0.2.0", only: :test}]
end

and fetch $ mix deps.get.

Usage

Replace use ExUnit.Case into use PowerAssert in your test code:

## before(ExUnit)
defmodule YourAwesomeTest do
  use ExUnit.Case  # <-- **HERE**
end

## after(PowerAssert)
defmodule YourAwesomeTest do
  use PowerAssert  # <-- **REPLACED**
end

Done! You can run $ mix test.

Use with ExUnit.CaseTemplate

Insert use PowerAssert with ExUnit.CaseTemplate.using/2 macro:

## before(ExUnit.CaseTemplate)
defmodule YourAwesomeTest do
  use ExUnit.CaseTemplate
end

## after(PowerAssert)
defmodule YourAwesomeTest do
  use ExUnit.CaseTemplate

  # add the following
  using do
    quote do
      use PowerAssert
    end
  end
end

protip: useful command to replace use ExUnit.Case

$ git grep -l 'use ExUnit\.Case' | xargs sed -i.bak -e 's/use ExUnit\.Case/use PowerAssert/g'

How to use with other framework depending on ExUnit such as ExSpec

ExSpec

Append use PowerAssert after use ExSpec:

defmodule ExSpecBasedTest do
  use ExSpec
  use PowerAssert   # <-- append

  describe "describe" do
    it "it" do
      assert something == "hoge"
    end
  end
end

See also: test/ex_spec/ex_spec_test.exs

API

Only provide assert macro:

assert(expression, message \\ nil)

Dependencies

Limitation

Resources

Author

Takayuki Matsubara (@ma2ge on twitter)

License

Distributed under the Apache 2 License.

Check LICENSE files for more information.