blocks: invert if/unless with !=. Closes #132

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## main
 
+### Improvements
+
+* blocks: invert if and unless with `!=` or `!==`, like we do for `!` and `not`. Closes #132
+
 ## v0.11.9
 
 ### Improvements

lib/style/blocks.ex

@@ -30,7 +30,7 @@ defmodule Styler.Style.Blocks do
   alias Styler.Style
   alias Styler.Zipper
 
-  defguardp is_negator(n) when n in [:!, :not]
+  defguardp is_negator(n) when elem(n, 0) in [:!, :not, :!=, :!==]
 
   # case statement with exactly 2 `->` cases
   # rewrite to `if` if it's any of 3 trivial cases
@@ -163,8 +163,8 @@ defmodule Styler.Style.Blocks do
         zipper |> Zipper.replace({:if, m, [{:!, hm, [head]}, do_else]}) |> run(ctx)
 
       # Credo.Check.Refactor.NegatedConditionsInUnless
-      [{negator, _, [expr]}, [{do_, do_body}]] when is_negator(negator) ->
-        zipper |> Zipper.replace({:if, m, [expr, [{do_, do_body}]]}) |> run(ctx)
+      [negator, [{do_, do_body}]] when is_negator(negator) ->
+        zipper |> Zipper.replace({:if, m, [invert(negator), [{do_, do_body}]]}) |> run(ctx)
 
       _ ->
         {:cont, zipper, ctx}
@@ -174,12 +174,12 @@ defmodule Styler.Style.Blocks do
   def run({{:if, m, children}, _} = zipper, ctx) do
     case children do
       # Credo.Check.Refactor.NegatedConditionsWithElse
-      [{negator, _, [expr]}, [{do_, do_body}, {else_, else_body}]] when is_negator(negator) ->
-        zipper |> Zipper.replace({:if, m, [expr, [{do_, else_body}, {else_, do_body}]]}) |> run(ctx)
+      [negator, [{do_, do_body}, {else_, else_body}]] when is_negator(negator) ->
+        zipper |> Zipper.replace({:if, m, [invert(negator), [{do_, else_body}, {else_, do_body}]]}) |> run(ctx)
 
       # if not x, do: y => unless x, do: y
-      [{negator, _, [expr]}, [do_block]] when is_negator(negator) ->
-        zipper |> Zipper.replace({:unless, m, [expr, [do_block]]}) |> run(ctx)
+      [negator, [do_block]] when is_negator(negator) ->
+        zipper |> Zipper.replace({:unless, m, [invert(negator), [do_block]]}) |> run(ctx)
 
       # drop `else: nil`
       [head, [do_block, {_, {:__block__, _, [nil]}}]] ->
@@ -317,4 +317,8 @@ defmodule Styler.Style.Blocks do
 
     max_line
   end
+
+  defp invert({:!=, m, [a, b]}), do: {:==, m, [a, b]}
+  defp invert({:!==, m, [a, b]}), do: {:===, m, [a, b]}
+  defp invert({_, _, [expr]}), do: expr
 end

test/style/blocks_test.exs

@@ -793,6 +793,25 @@ defmodule Styler.Style.BlocksTest do
         )
       end
 
+      for negator <- ["!=", "!=="], inverse = String.replace(negator, "!", "=") do
+        assert_style(
+          """
+          unless x #{negator} y do
+            b
+          else
+            c
+          end
+          """,
+          """
+          if x #{inverse} y do
+            b
+          else
+            c
+          end
+          """
+        )
+      end
+
       assert_style(
         """
         unless a do
@@ -828,6 +847,23 @@ defmodule Styler.Style.BlocksTest do
           """
         )
       end
+
+      for negator <- ["!=", "!=="], inverse = String.replace(negator, "!", "=") do
+        assert_style("unless a #{negator} b, do: :bar", "if a #{inverse} b, do: :bar")
+
+        assert_style(
+          """
+          unless a #{negator} b do
+            c
+          end
+          """,
+          """
+          if a #{inverse} b do
+            c
+          end
+          """
+        )
+      end
     end
 
     test "Credo.Check.Refactor.NegatedConditionsWithElse" do
@@ -851,6 +887,27 @@ defmodule Styler.Style.BlocksTest do
           """
         )
       end
+
+      for negator <- ["!=", "!=="], inverse = String.replace(negator, "!", "=") do
+        assert_style("if a #{negator} b, do: :bar, else: :baz", "if a #{inverse} b, do: :baz, else: :bar")
+
+        assert_style(
+          """
+          if a #{negator} b do
+            bar
+          else
+            baz
+          end
+          """,
+          """
+          if a #{inverse} b do
+            baz
+          else
+            bar
+          end
+          """
+        )
+      end
     end
 
     test "recurses" do
@@ -887,6 +944,8 @@ defmodule Styler.Style.BlocksTest do
         end
         """
       )
+
+      assert_style("if not (a != b), do: c", "if a == b, do: c")
     end
 
     test "comments and flips" do