fix(dashboard): add EMMS exclusion to recentf-exclude without clobbering it

dashboard-config used setq on recentf-exclude, discarding the five exclusions system-defaults adds earlier in init order (bookmarks, elpa, recentf, ElfeedDB, airootfs). Extract the EMMS exclusion into cj/--dashboard-exclude-emms-from-recentf (the :config side-effect was not reachable for a test) and use add-to-list so prior entries survive. Two ERT tests cover preservation and the added pattern.

2 files changed, 40 insertions, 1 deletions

diff --git a/modules/dashboard-config.el b/modules/dashboard-config.el
index b4e4545d0..c70b78c2d 100644
--- a/modules/dashboard-config.el
+++ b/modules/dashboard-config.el
@@ -145,6 +145,12 @@ window."
 ;; --------------------------------- Dashboard ---------------------------------
 ;; a useful startup screen for Emacs
 
+(defun cj/--dashboard-exclude-emms-from-recentf ()
+  "Exclude the EMMS history file from recentf.
+Adds to `recentf-exclude' so entries set elsewhere (e.g. in
+system-defaults) are preserved rather than overwritten."
+  (add-to-list 'recentf-exclude "/emms/history"))
+
 (use-package dashboard
   :demand t
   :hook (emacs-startup . cj/dashboard-only)
@@ -196,7 +202,7 @@ window."
   (setq dashboard-bookmarks-show-path nil)                            ;; don't show paths in bookmarks
   (setq dashboard-recentf-show-base t)                                ;; show filename, not full path
   (setq dashboard-recentf-item-format "%s")
-  (setq recentf-exclude '("/emms/history"))                            ;; exclude EMMS history from recent files
+  (cj/--dashboard-exclude-emms-from-recentf)                            ;; exclude EMMS history from recent files
   (setq dashboard-set-footer nil)                                     ;; don't show footer and quotes
 
   ;; == navigation
diff --git a/tests/test-dashboard-config-recentf-exclude.el b/tests/test-dashboard-config-recentf-exclude.el
new file mode 100644
index 000000000..f35b3eda1
--- /dev/null
+++ b/tests/test-dashboard-config-recentf-exclude.el
@@ -0,0 +1,33 @@
+;;; test-dashboard-config-recentf-exclude.el --- recentf-exclude is not clobbered -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; `cj/--dashboard-exclude-emms-from-recentf' adds the EMMS history pattern
+;; to `recentf-exclude'.  It must ADD to the list, not replace it, or it
+;; wipes the exclusions system-defaults.el set earlier in init order
+;; (emacs_bookmarks, elpa, recentf, ElfeedDB, airootfs).
+
+;;; Code:
+
+(require 'ert)
+(require 'recentf)   ; makes `recentf-exclude' special so the let below is dynamic
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'testutil-general)
+(require 'dashboard-config)
+
+(ert-deftest test-dashboard-config-exclude-emms-preserves-existing-entries ()
+  "Error: excluding the EMMS history preserves prior recentf-exclude entries."
+  (let ((recentf-exclude (list "emacs_bookmarks" "airootfs")))
+    (cj/--dashboard-exclude-emms-from-recentf)
+    (should (member "/emms/history" recentf-exclude))
+    (should (member "emacs_bookmarks" recentf-exclude))
+    (should (member "airootfs" recentf-exclude))))
+
+(ert-deftest test-dashboard-config-exclude-emms-adds-the-pattern ()
+  "Normal: the EMMS history pattern is present after the call."
+  (let ((recentf-exclude nil))
+    (cj/--dashboard-exclude-emms-from-recentf)
+    (should (member "/emms/history" recentf-exclude))))
+
+(provide 'test-dashboard-config-recentf-exclude)
+;;; test-dashboard-config-recentf-exclude.el ends here