diagnostic: check for bad tap files.

Check for Ruby files in taps that are outside of the detected `Formula`
directory for a tap but inside one of the other potential directories.

This usually indicates a formula has been added in the wrong directory
in a tap and is used to fail CI in this case.

1 files changed, 5 insertions, 1 deletions

diff --git a/Library/Homebrew/tap.rb b/Library/Homebrew/tap.rb
index 68b21ac60..4b59f2344 100644
--- a/Library/Homebrew/tap.rb
+++ b/Library/Homebrew/tap.rb
@@ -292,7 +292,11 @@ class Tap
 
   # path to the directory of all {Formula} files for this {Tap}.
   def formula_dir
-    @formula_dir ||= [path/"Formula", path/"HomebrewFormula", path].detect(&:directory?)
+    @formula_dir ||= potential_formula_dirs.detect(&:directory?)
+  end
+
+  def potential_formula_dirs
+    @potential_formula_dirs ||= [path/"Formula", path/"HomebrewFormula", path].freeze
   end
 
   # path to the directory of all {Cask} files for this {Tap}.