Implement dbg for unless/2 expressions (#13620)

Author: sabiwara

lib/elixir/lib/macro.ex

@@ -2642,16 +2642,17 @@ defmodule Macro do
     end
   end
 
-  defp dbg_ast_to_debuggable({:if, meta, [condition_ast, clauses]} = ast, env) do
-    case Macro.Env.lookup_import(env, {:if, 2}) do
+  defp dbg_ast_to_debuggable({op, meta, [condition_ast, clauses]} = ast, env)
+       when op in [:if, :unless] do
+    case Macro.Env.lookup_import(env, {op, 2}) do
       [macro: Kernel] ->
         condition_result_var = unique_var(:condition_result, __MODULE__)
 
         quote do
           unquote(condition_result_var) = unquote(condition_ast)
-          result = unquote({:if, meta, [condition_result_var, clauses]})
+          result = unquote({op, meta, [condition_result_var, clauses]})
 
-          {:if, unquote(escape(ast)), unquote(escape(condition_ast)),
+          {unquote(op), unquote(escape(ast)), unquote(escape(condition_ast)),
            unquote(condition_result_var), result}
         end
 
@@ -2774,15 +2775,18 @@ defmodule Macro do
   end
 
   defp dbg_format_ast_to_debug(
-         {:if, ast, condition_ast, condition_result, result},
+         {op, ast, condition_ast, condition_result, result},
          options
-       ) do
+       )
+       when op in [:if, :unless] do
+    op_name = String.capitalize(Atom.to_string(op))
+
     formatted = [
-      dbg_maybe_underline("If condition", options),
+      dbg_maybe_underline("#{op_name} condition", options),
       ":\n",
       dbg_format_ast_with_value(condition_ast, condition_result, options),
       ?\n,
-      dbg_maybe_underline("If expression", options),
+      dbg_maybe_underline("#{op_name} expression", options),
       ":\n",
       dbg_format_ast_with_value(ast, result, options)
     ]

lib/elixir/test/elixir/macro_test.exs

@@ -542,7 +542,7 @@ defmodule MacroTest do
              """
     end
 
-    test "if statement" do
+    test "if expression" do
       x = true
       map = %{a: 5, b: 1}
 
@@ -572,7 +572,7 @@ defmodule MacroTest do
              """
     end
 
-    test "if statement without else" do
+    test "if expression without else" do
       x = true
       map = %{a: 5, b: 1}
 
@@ -618,6 +618,36 @@ defmodule MacroTest do
              """
     end
 
+    test "unless expression" do
+      x = false
+      map = %{a: 5, b: 1}
+
+      {result, formatted} =
+        dbg_format(
+          unless true and x do
+            map[:a] * 2
+          else
+            map[:b]
+          end
+        )
+
+      assert result == 10
+
+      assert formatted =~ "macro_test.exs"
+
+      assert formatted =~ """
+             Unless condition:
+             true and x #=> false
+
+             Unless expression:
+             unless true and x do
+               map[:a] * 2
+             else
+               map[:b]
+             end #=> 10
+             """
+    end
+
     test "with \"syntax_colors: []\" it doesn't print any color sequences" do
       {_result, formatted} = dbg_format("hello")
       refute formatted =~ "\e["