Show hints for mix test --no-color (#14198)

Author: NickNeck

lib/ex_unit/lib/ex_unit/formatter.ex

@@ -477,7 +477,19 @@ defmodule ExUnit.Formatter do
     content_width = if width == :infinity, do: width, else: width - padding_size
 
     case format_diff(left, right, context, formatter) do
-      {result, env} ->
+      {nil, hints} when is_atom(context) ->
+        {if_value(left, inspect), if_value(right, inspect), hints}
+
+      {nil, hints} ->
+        left =
+          Macro.prewalk(left, fn
+            {_, [original: original], _} -> original
+            other -> other
+          end)
+
+        {if_value(left, &code_multiline(&1, padding_size)), if_value(right, inspect), hints}
+
+      {result, hints} ->
         left =
           result.left
           |> Diff.to_algebra(&colorize_diff_delete(&1, formatter))
@@ -490,32 +502,25 @@ defmodule ExUnit.Formatter do
           |> Algebra.nest(padding_size)
           |> Algebra.format(content_width)
 
-        {left, right, Enum.map(env.hints, &{:hint, format_hint(&1)})}
-
-      nil when is_atom(context) ->
-        {if_value(left, inspect), if_value(right, inspect), []}
-
-      nil ->
-        left =
-          Macro.prewalk(left, fn
-            {_, [original: original], _} -> original
-            other -> other
-          end)
+        {left, right, hints}
+    end
+  end
 
-        {if_value(left, &code_multiline(&1, padding_size)), if_value(right, inspect), []}
+  defp format_diff(left, right, context, formatter) do
+    if has_value?(left) and has_value?(right) do
+      {result, env} = find_diff(left, right, context)
+      result = if formatter.(:diff_enabled?, false), do: result
+      hints = Enum.map(env.hints, &{:hint, format_hint(&1)})
+      {result, hints}
+    else
+      {nil, []}
     end
   end
 
   defp format_hint(:equivalent_but_different_strings) do
     "you are comparing strings that have the same visual representation but are made of different Unicode codepoints"
   end
 
-  defp format_diff(left, right, context, formatter) do
-    if has_value?(left) and has_value?(right) and formatter.(:diff_enabled?, false) do
-      find_diff(left, right, context)
-    end
-  end
-
   defp colorize_diff_delete(doc, formatter) do
     format = colorize_format(doc, :diff_delete, :diff_delete_whitespace)
     formatter.(format, doc)

lib/ex_unit/test/ex_unit/formatter_test.exs

@@ -332,6 +332,9 @@ defmodule ExUnit.FormatterTest do
                 hint:  you are comparing strings that have the same visual representation but are made of different Unicode codepoints
            """
 
+    assert format_test_failure(test(), failure, 1, 80, &diff_formatter/2) ==
+             format_test_failure(test(), failure, 1, 80, &formatter/2)
+
     assert format_assertion_diff(assertion_error, 0, :infinity, &diff_formatter/2)
            |> kw_to_string() ==
              [