Rewrite with true <- ... to if statements. Closes #173

CHANGELOG.md

@@ -5,9 +5,15 @@ they can and will change without that change being reflected in Styler's semanti
 
 ## main
 
+### Improvements
+
+#### `with`
+
+* remove `with` structure with no left arrows in its head to be normal code (#174)
+* `with true <- x(), do: y` => `if x(), do: y` (#173)
+
 ### Fixes
 
-* rewrite `with` with no left arrows to be normal code (#174)
 * fix `with` arrow replacement + redundant body removal creating invalid statements (#184, h/t @JesseHerrick)
 * allow Kernel unary `!` and `not` as valid pipe starts (#183, h/t @nherzing)
 

lib/style/blocks.ex

@@ -59,6 +59,22 @@ defmodule Styler.Style.Blocks do
     run({{:case, m, [single_statement, clauses]}, zm}, ctx)
   end
 
+  # `with true <- x, do: bar` =>`if x, do: bar`
+  def run({{:with, m, [{:<-, _, [{_, _, [true]}, rhs]}, [do_kwl]]}, _} = zipper, ctx) do
+    children =
+      case rhs do
+        # `true <- foo || {:error, :shouldve_used_an_if_statement}``
+        # turn the rhs of an `||` into an else body
+        {:||, _, [head, else_body]} ->
+          [head, [do_kwl, {{:__block__, [line: m[:line] + 2], [:else]}, Style.shift_line(else_body, 3)}]]
+
+        _ ->
+          [rhs, [do_kwl]]
+      end
+
+    {:cont, Zipper.replace(zipper, {:if, m, children}), ctx}
+  end
+
   # Credo.Check.Refactor.WithClauses
   def run({{:with, with_meta, children}, _} = zipper, ctx) when is_list(children) do
     # a std lib `with` block will have at least one left arrow and a `do` body. anything else we skip ¯\_(ツ)_/¯

test/style/blocks_test.exs

@@ -556,6 +556,40 @@ defmodule Styler.Style.BlocksTest do
       )
     end
 
+    test "with to if" do
+      assert_style(
+        """
+        with true <- foo do
+          boop
+          bar
+        end
+        """,
+        """
+        if foo do
+          boop
+          bar
+        end
+        """
+      )
+
+      assert_style "with true <- x, do: bar", "if x, do: bar"
+
+      assert_style(
+        """
+        with true <- foo || {:error, :shouldve_used_an_if_statement} do
+          bar
+        end
+        """,
+        """
+        if foo do
+          bar
+        else
+          {:error, :shouldve_used_an_if_statement}
+        end
+        """
+      )
+    end
+
     test "switches keyword do to block do when adding postroll" do
       assert_style(
         """