MoxInject

Maps between modules, the behaviours they implement and their mocks (using Hammox or Mox) in tests:

use AnotherModule do
    alias X, as: @x
    ...
    @x.f()
end

This will assign each dependency, or its test substitute, to the given module attribute.

Example:

use AnotherModule do
    alias Phoenix.LiveView.JS, as: @js
end

...
@js.hide(...)
...

See Examples and Configuration for how to ensure the correct behaviour is located for a given module, so that a mocking library can be used.

To replace with mocks:

if Mix.env() == :test do
    config :mox_inject, test_dependencies?: true
end

and add a file test/support/mocks.ex - so that this file is compiled (and evaluated) before the test run:

MoxInject.Test.setup_mocks(Mox) # or Hammox

And in tests:

Phoenix.LiveView.JS.Mock
|> expect(:hide, ...)

Examples

Look at lib/mox_inject/test_module.ex and test/mox_inject_test.exs.

Configuration

Either the module in question will have a Behaviour submodule, as a convention:

defmodule X.Behaviour do
    @callback f :: :ok
end

defmodule X do
    @behaviour __MODULE__.Behaviour

    @impl true
    def f do
        ...
    end
end

in configuration:

config :mox_inject, :modules_with_behaviour_submodules, [X]

or, for example, an explicit behaviour can be provided for an existing module.

defmodule ExternalBehaviour.PhoenixLiveViewJS do
    @callback ...
end

and in configuration:

config :mox_inject, :explicit_behaviours, %{
    Phoenix.LiveView.JS => ExternalBehaviour.PhoenixLiveViewJS
}

to ensure that the mocking library can find the behaviour for the module.

Installation

The package can be installed by adding mox_inject to your list of dependencies in mix.exs:

def deps do
  [
    {:mox_inject, "~> 0.1.0"}
  ]
end

Documentation and example usage can be found at https://hexdocs.pm/mox_inject.