feat: Igniter.Code.Module.move_to_attribute_definition (#207)

lib/igniter/code/module.ex

@@ -109,6 +109,43 @@ defmodule Igniter.Code.Module do
     Igniter.Code.Function.move_to_def(zipper, fun, arity)
   end
 
+  @doc """
+  Move to an attribute definition inside a module.
+
+  ## Example
+
+  Given this module:
+
+      defmodule MyAppWeb.Endpoint do
+        @doc "My App Endpoint"
+
+        @session_options [
+          store: :cookie,
+          ...
+        ]
+      end
+
+  You can move into `@doc` attribute with:
+
+      Igniter.Code.Module.move_to_attribute_definition(zipper, :doc)
+
+  Or you can move into `@session_options` constant with:
+
+      Igniter.Code.Module.move_to_attribute_definition(zipper, :session_options)
+
+  """
+  @spec move_to_attribute_definition(Zipper.t(), atom()) :: {:ok, Zipper.t()} | :error
+  def move_to_attribute_definition(zipper, name) when is_atom(name) do
+    with {:ok, zipper} <- Igniter.Code.Module.move_to_defmodule(zipper),
+         {:ok, zipper} <- Common.move_to_do_block(zipper),
+         {:ok, zipper} <- Common.move_to_pattern(zipper, {:@, _, [{^name, _, _}]}) do
+      {:ok, zipper}
+    else
+      _ ->
+        :error
+    end
+  end
+
   def module?(zipper) do
     Common.node_matches_pattern?(zipper, {:__aliases__, _, [_ | _]})
   end

test/igniter/code/module_test.exs

@@ -136,4 +136,24 @@ defmodule Igniter.Code.ModuleTest do
                end)
     end
   end
+
+  test "move_to_attribute_definition" do
+    mod_zipper =
+      ~s"""
+      defmodule MyApp.Foo do
+        @doc "My app module doc"
+        @foo_key Application.compile_env!(:my_app, :key)
+      end
+      """
+      |> Sourceror.parse_string!()
+      |> Sourceror.Zipper.zip()
+
+    assert {:ok, zipper} = Igniter.Code.Module.move_to_attribute_definition(mod_zipper, :doc)
+    assert Igniter.Util.Debug.code_at_node(zipper) == ~s|@doc "My app module doc"|
+
+    assert {:ok, zipper} = Igniter.Code.Module.move_to_attribute_definition(mod_zipper, :foo_key)
+
+    assert Igniter.Util.Debug.code_at_node(zipper) ==
+             "@foo_key Application.compile_env!(:my_app, :key)"
+  end
 end