refactor(prog-general): lift cj/find-project-root-file out of :config

The pure project-root file finder lived inside the projectile use-package :config, so it was unreachable under make test. Move it to top level (its forward declaration already existed); cj/open-project-root-todo and cj/project-switch-actions still call it. Adds unit coverage for string regexps, rx forms, no-match, and no-project.

2 files changed, 62 insertions, 14 deletions

diff --git a/modules/prog-general.el b/modules/prog-general.el
index 53f20ce46..ae48bc9cb 100644
--- a/modules/prog-general.el
+++ b/modules/prog-general.el
@@ -64,9 +64,21 @@
 (defvar treesit-auto-recipe-list)
 
 ;; Forward declarations for functions defined later in this file
-(declare-function cj/find-project-root-file "prog-general")
 (declare-function cj/project-switch-actions "prog-general")
 (declare-function cj/deadgrep--initial-term "prog-general")
+
+(defun cj/find-project-root-file (regexp)
+  "Return first file in the current Projectile project root matching REGEXP.
+
+Match is done against (downcase file) for case-insensitivity.
+REGEXP must be a string or an rx form."
+  (when-let ((root (projectile-project-root)))
+    (seq-find (lambda (file)
+                (string-match-p (if (stringp regexp)
+                                    regexp
+                                  (rx-to-string regexp))
+                                (downcase file)))
+              (directory-files root))))
 (declare-function cj/highlight-indent-guides-disable-in-non-prog-modes "prog-general")
 
 ;; --------------------- General Programming Mode Settings ---------------------
@@ -177,19 +189,6 @@ reuses the current window otherwise, matching `cj/open-project-root-todo'."
   :config
   (require 'seq)
 
-  (defun cj/find-project-root-file (regexp)
-	"Return first file in the current Projectile project root matching REGEXP.
-
-Match is done against (downcase file) for case-insensitivity.
-REGEXP must be a string or an rx form."
-	(when-let ((root (projectile-project-root)))
-	  (seq-find (lambda (file)
-				  (string-match-p (if (stringp regexp)
-									  regexp
-									(rx-to-string regexp))
-								  (downcase file)))
-				(directory-files root))))
-
   (defun cj/open-project-root-todo ()
 	"Open todo.org in the current Projectile project root.
 
diff --git a/tests/test-prog-general--find-project-root-file.el b/tests/test-prog-general--find-project-root-file.el
new file mode 100644
index 000000000..97db0b979
--- /dev/null
+++ b/tests/test-prog-general--find-project-root-file.el
@@ -0,0 +1,49 @@
+;;; test-prog-general--find-project-root-file.el --- Tests for cj/find-project-root-file -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; cj/find-project-root-file returns the first file in the current Projectile
+;; project root matching a regexp (string or rx form), case-insensitively.  It
+;; was defined inside the projectile use-package :config (unreachable under
+;; `make test'); lifting it to top level makes it unit-testable.  projectile's
+;; root and directory-files are mocked at the boundary.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(require 'seq)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'prog-general)
+
+(defmacro test-prg--with-root (files &rest body)
+  "Run BODY with projectile-project-root \"/proj/\" and directory-files = FILES."
+  (declare (indent 1))
+  `(cl-letf (((symbol-function 'projectile-project-root) (lambda (&rest _) "/proj/"))
+             ((symbol-function 'directory-files) (lambda (&rest _) ,files)))
+     ,@body))
+
+(ert-deftest test-prg-find-root-file-string-regexp ()
+  "Normal: a string regexp matches case-insensitively."
+  (test-prg--with-root '("README.md" "TODO.org" "src")
+    (should (equal (cj/find-project-root-file "^todo\\.org$") "TODO.org"))))
+
+(ert-deftest test-prg-find-root-file-rx-form ()
+  "Normal: an rx form is converted and matched."
+  (test-prg--with-root '("notes.txt" "todo.md" "x")
+    (should (equal (cj/find-project-root-file
+                    '(seq bos "todo." (or "org" "md" "txt") eos))
+                   "todo.md"))))
+
+(ert-deftest test-prg-find-root-file-no-match ()
+  "Boundary: no matching file yields nil."
+  (test-prg--with-root '("a.el" "b.el")
+    (should (null (cj/find-project-root-file "^todo\\.org$")))))
+
+(ert-deftest test-prg-find-root-file-no-project ()
+  "Boundary: outside a project (nil root) yields nil."
+  (cl-letf (((symbol-function 'projectile-project-root) (lambda (&rest _) nil)))
+    (should (null (cj/find-project-root-file "^todo\\.org$")))))
+
+(provide 'test-prog-general--find-project-root-file)
+;;; test-prog-general--find-project-root-file.el ends here