Rewire (rewire v0.3.1) View Source

Rewire is a libary for replacing hard-wired dependencies of the module your unit testing. This allows you to keep your production code free of any unit testing-specific concerns.

Example

defmodule Conversation do
  def start(), do: English.greet()              # the dependency is hard-wired
end

You can rewire the dependency with a mock, using mox for example:

defmodule MyTest do
  use ExUnit.Case
  use Rewire
  import Mox

  rewire Conversation, English: Mock            # acts as an alias to the rewired module

  test "greet" do
    stub(Mock, :greet, fn -> "bonjour" end)
    assert Conversation.start() == "bonjour"    # this uses Mock now!
  end
end

defmodule MyTest do
  use ExUnit.Case
  use Rewire
  import Mox

  rewire Conversation, English: Mock            # acts as an alias to the rewired module

  test "greet" do
    stub(Mock, :greet, fn -> "bonjour" end)
    assert Conversation.start() == "bonjour"    # this uses Mock now!
  end
end

Alternatively, you can also rewire a module on a test-by-test basis:

defmodule MyTest do
  use ExUnit.Case
  use Rewire
  import Mox

  test "greet" do
    rewire Conversation, English: Mock do       # within the block it is rewired
      stub(Mock, :greet, fn -> "bonjour" end)
      assert Conversation.start() == "bonjour"  # this uses Mock now!
    end
  end
end

You can also give the alias a different name using as:

  rewire Conversation, English: Mock, as: SmallTalk

Link to this section Summary

Functions

rewire(rewire_expr, opts)

Macro that allows to rewire (and alias) a module.

rewire(rewire_expr, opts, list)

Macro that allows to rewire a module within a block.

Link to this section Functions

rewire(rewire_expr, opts)

(macro)

Macro that allows to rewire (and alias) a module.

use Rewire

rewire App.ModuleToRewire, ModuleDep: Mock

# `ModuleToRewire` will use `Mock` now
end

Options

opts is a keyword list:

as - give the rewired module a different name
any other item, like ModuleDep: Mock, will be interpreted as a mapping from one module to another

rewire(rewire_expr, opts, list)

(macro)

Macro that allows to rewire a module within a block.

use Rewire

rewire App.ModuleToRewire, ModuleDep: Mock do
  # `ModuleToRewire` will use `Mock` now
end

See rewire/2 for a description of options.