Start matching pathname directory prefixes more rigorously

Fixes #1174

The simplistic `start_with?` check was not sufficient to match that a
given file/folder was under a given folder, since we were not explicitly
checking for full folder name matches. For example, if
`path = "/foo/bar-gem/baz"` and `folder = "/foo/bar"`, then
`path.start_with?(folder)` would return `true`, but `path` is not under
the `folder` directory.

This commit fixes the problem by matching `folder` to any of the parent
directories of `path` by using the `Pathname#ascend` method to get all
parent directory prefixes of a `path`.

lib/tapioca/gemfile.rb

@@ -201,7 +201,7 @@ def contains_path?(path)
         if default_gem?
           files.any? { |file| file.to_s == to_realpath(path) }
         else
-          to_realpath(path).start_with?(full_gem_path) || has_parent_gemspec?(path)
+          path_in_dir?(to_realpath(path), full_gem_path) || has_parent_gemspec?(path)
         end
       end
 

lib/tapioca/helpers/gem_helper.rb

@@ -8,12 +8,13 @@ module GemHelper
     sig { params(gemfile_dir: String, full_gem_path: String).returns(T::Boolean) }
     def gem_in_app_dir?(gemfile_dir, full_gem_path)
       !gem_in_bundle_path?(to_realpath(full_gem_path)) &&
-        full_gem_path.start_with?(to_realpath(gemfile_dir))
+        path_in_dir?(to_realpath(gemfile_dir), full_gem_path)
     end
 
     sig { params(full_gem_path: String).returns(T::Boolean) }
     def gem_in_bundle_path?(full_gem_path)
-      full_gem_path.start_with?(Bundler.bundle_path.to_s, Bundler.app_cache.to_s)
+      path_in_dir?(full_gem_path, Bundler.bundle_path) ||
+        path_in_dir?(full_gem_path, Bundler.app_cache)
     end
 
     sig { params(path: T.any(String, Pathname)).returns(String) }
@@ -22,5 +23,14 @@ def to_realpath(path)
       path_string = File.realpath(path_string) if File.exist?(path_string)
       path_string
     end
+
+    private
+
+    sig { params(path: T.any(Pathname, String), dir: T.any(Pathname, String)).returns(T::Boolean) }
+    def path_in_dir?(path, dir)
+      dir = Pathname.new(dir)
+      path = Pathname.new(path)
+      path.ascend.any?(dir)
+    end
   end
 end