Add configuration for modules to exclude for alias lifting

lib/style/module_directives.ex

@@ -102,7 +102,7 @@ defmodule Styler.Style.ModuleDirectives do
         # we want only-child literal block to be handled in the only-child catch-all. it means someone did a weird
         # (that would be a literal, so best case someone wrote a string and forgot to put `@moduledoc` before it)
         {:__block__, _, [_, _ | _]} ->
-          {:skip, organize_directives(body_zipper, moduledoc), ctx}
+          {:skip, organize_directives(body_zipper, ctx, moduledoc), ctx}
 
         # a module whose only child is a moduledoc. nothing to do here!
         # seems weird at first blush but lots of projects/libraries do this with their root namespace module
@@ -128,7 +128,7 @@ defmodule Styler.Style.ModuleDirectives do
   def run({{directive, _, children}, _} = zipper, ctx) when directive in @directives and is_list(children) do
     # Need to be careful that we aren't getting false positives on variables or fns like `def import(foo)` or `alias = 1`
     case Style.ensure_block_parent(zipper) do
-      {:ok, zipper} -> {:skip, zipper |> Zipper.up() |> organize_directives(), ctx}
+      {:ok, zipper} -> {:skip, zipper |> Zipper.up() |> organize_directives(ctx), ctx}
       # not actually a directive! carry on.
       :error -> {:cont, zipper, ctx}
     end
@@ -173,7 +173,7 @@ defmodule Styler.Style.ModuleDirectives do
   # a dynamic module name, like `defmodule my_variable do ... end`
   defp moduledoc(_), do: nil
 
-  defp organize_directives(parent, moduledoc \\ nil) do
+  defp organize_directives(parent, ctx, moduledoc \\ nil) do
     {directives, nondirectives} =
       parent
       |> Zipper.children()
@@ -201,7 +201,7 @@ defmodule Styler.Style.ModuleDirectives do
     aliases = expand_and_sort(directives[:alias] || [])
     requires = expand_and_sort(directives[:require] || [])
 
-    {aliases, requires, nondirectives} = lift_aliases(aliases, requires, nondirectives)
+    {aliases, requires, nondirectives} = lift_aliases(aliases, requires, nondirectives, ctx.config.lift_exclude)
 
     directives =
       [
@@ -229,9 +229,9 @@ defmodule Styler.Style.ModuleDirectives do
     end
   end
 
-  defp lift_aliases(aliases, requires, nondirectives) do
+  defp lift_aliases(aliases, requires, nondirectives, excluded_by_config) do
     excluded =
-      Enum.reduce(aliases, @stdlib, fn
+      Enum.reduce(aliases, MapSet.union(@stdlib, excluded_by_config), fn
         {:alias, _, [{:__aliases__, _, aliases}]}, excluded -> MapSet.put(excluded, List.last(aliases))
         {:alias, _, [{:__aliases__, _, _}, [{_as, {:__aliases__, _, [as]}}]]}, excluded -> MapSet.put(excluded, as)
         # `alias __MODULE__` or other oddities

lib/styler.ex

@@ -31,7 +31,9 @@ defmodule Styler do
   def style({ast, comments}, file, opts) do
     on_error = opts[:on_error] || :log
     zipper = Zipper.zip(ast)
-    context = %{comments: comments, file: file}
+    excludes = MapSet.new(List.wrap(opts[:alias_lifting_exclude]))
+
+    context = %{comments: comments, file: file, config: %{lift_exclude: excludes}}
 
     {{ast, _}, %{comments: comments}} =
       Enum.reduce(@styles, {zipper, context}, fn style, {zipper, context} ->
@@ -58,13 +60,14 @@ defmodule Styler do
   def features(_opts), do: [sigils: [], extensions: [".ex", ".exs"]]
 
   @impl Format
-  def format(input, formatter_opts, opts \\ []) do
+  def format(input, formatter_opts) do
     file = formatter_opts[:file]
+    styler_opts = formatter_opts[:styler] || []
 
     {ast, comments} =
       input
       |> string_to_quoted_with_comments(to_string(file))
-      |> style(file, opts)
+      |> style(file, styler_opts)
 
     quoted_to_string(ast, comments, formatter_opts)
   end
@@ -81,7 +84,7 @@ defmodule Styler do
   end
 
   @doc false
-  def literal_encoder(a, b), do: {:ok, {:__block__, b, [a]}}
+  def literal_encoder(literal, meta), do: {:ok, {:__block__, meta, [literal]}}
 
   @doc false
   # Turns an ast and comments back into code, formatting it along the way.

test/style/module_directives/alias_lifting_test.exs

@@ -179,6 +179,18 @@ defmodule Styler.Style.ModuleDirectives.AliasLiftingTest do
   end
 
   describe "it doesn't lift" do
+    test "collisions with configured modules" do
+      assert_style(
+        """
+        alias Foo.Bar
+
+        A.B.C
+        A.B.C
+        """,
+        alias_lifting_exclude: ~w(C)a
+      )
+    end
+
     test "collisions with std lib" do
       assert_style """
       defmodule DontYouDare do

test/support/style_case.ex

@@ -16,18 +16,16 @@ defmodule Styler.StyleCase do
 
   using do
     quote do
-      import unquote(__MODULE__), only: [assert_style: 1, assert_style: 2, style: 1]
+      import unquote(__MODULE__), only: [assert_style: 1, assert_style: 2, style: 1, style: 2]
     end
   end
 
-  defmacro assert_style(before, expected \\ nil) do
-    expected = expected || before
-
-    quote bind_quoted: [before: before, expected: expected] do
+  defmacro assert_style(before, expected, options) do
+    quote bind_quoted: [before: before, expected: expected, options: options] do
       alias Styler.Zipper
 
       expected = String.trim(expected)
-      {styled_ast, styled, styled_comments} = style(before)
+      {styled_ast, styled, styled_comments} = style(before, options)
 
       if styled != expected and ExUnit.configuration()[:trace] do
         IO.puts("\n======Given=============\n")
@@ -89,7 +87,7 @@ defmodule Styler.StyleCase do
       end)
 
       assert expected == styled
-      {_, restyled, _} = style(styled)
+      {_, restyled, _} = style(styled, options)
 
       assert restyled == styled, """
       expected styling to be idempotent, but a second pass resulted in more changes.
@@ -107,9 +105,13 @@ defmodule Styler.StyleCase do
     end
   end
 
-  def style(code) do
+  def assert_style(no_change), do: assert_style(no_change, no_change, [])
+  def assert_style(before, expected) when is_binary(expected), do: assert_style(before, expected, [])
+  def assert_style(no_change, opts) when is_list(opts), do: assert_style(no_change, no_change, opts)
+
+  def style(code, options \\ []) do
     {ast, comments} = Styler.string_to_quoted_with_comments(code)
-    {styled_ast, comments} = Styler.style({ast, comments}, "testfile", on_error: :raise)
+    {styled_ast, comments} = Styler.style({ast, comments}, "testfile", [{:on_error, :raise} | options])
 
     try do
       styled_code = styled_ast |> Styler.quoted_to_string(comments) |> String.trim_trailing("\n")