refactor: move and test theme persistence behavior

1 files changed, 138 insertions, 0 deletions

diff --git a/tests/test-ui-theme-persistence.el b/tests/test-ui-theme-persistence.el
new file mode 100644
index 00000000..86ed9de9
--- /dev/null
+++ b/tests/test-ui-theme-persistence.el
@@ -0,0 +1,138 @@
+;;; test-ui-theme-persistence.el --- Tests for UI theme persistence -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Smoke and unit coverage for ui-theme.el persistence behavior.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+
+(require 'ui-theme)
+
+(ert-deftest test-ui-theme-default-theme-file-is-emacs-dotfile ()
+  "The default theme file should live under `user-emacs-directory'."
+  (should (equal theme-file
+                 (expand-file-name ".emacs-theme" user-emacs-directory)))
+  (should-not (string-match-p "emacs-theme\\.persist\\'" theme-file)))
+
+(ert-deftest test-ui-theme-read-missing-file-returns-nil ()
+  "Reading a missing theme file should return nil."
+  (let ((theme-file (expand-file-name "missing-theme" temporary-file-directory)))
+    (should-not (cj/theme-read-file-contents theme-file))))
+
+(ert-deftest test-ui-theme-write-file-contents-writes-content ()
+  "Writing theme content should persist exactly that content."
+  (let ((file (make-temp-file "ui-theme-write-")))
+    (unwind-protect
+        (progn
+          (should (cj/theme-write-file-contents "modus-vivendi" file))
+          (should (equal (cj/theme-read-file-contents file)
+                         "modus-vivendi")))
+      (delete-file file))))
+
+(ert-deftest test-ui-theme-write-file-contents-uses-write-region ()
+  "Theme persistence should write directly instead of visiting the file."
+  (let ((file (make-temp-file "ui-theme-write-region-"))
+        write-region-args
+        write-file-called)
+    (unwind-protect
+        (cl-letf (((symbol-function 'write-region)
+               (lambda (&rest args)
+                 (setq write-region-args args)
+                 nil))
+              ((symbol-function 'write-file)
+               (lambda (&rest _args)
+                 (setq write-file-called t)
+                 (error "write-file should not be used"))))
+          (should (cj/theme-write-file-contents "dupre" file)))
+      (delete-file file))
+    (should (equal (list (car write-region-args)
+                         (cadr write-region-args)
+                         (nth 2 write-region-args))
+                   (list "dupre" nil file)))
+    (should-not write-file-called)))
+
+(ert-deftest test-ui-theme-load-valid-persisted-theme ()
+  "A valid persisted theme should disable current themes and load that theme."
+  (let ((file (make-temp-file "ui-theme-valid-"))
+        (custom-enabled-themes '(old-theme))
+        disabled
+        loaded)
+    (unwind-protect
+        (progn
+          (cj/theme-write-file-contents "modus-vivendi" file)
+          (let ((theme-file file))
+            (cl-letf (((symbol-function 'disable-theme)
+                       (lambda (theme) (push theme disabled)))
+                      ((symbol-function 'load-theme)
+                       (lambda (theme &optional _no-confirm _no-enable)
+                         (push theme loaded))))
+              (cj/load-theme-from-file)))
+          (should (equal disabled '(old-theme)))
+          (should (equal loaded '(modus-vivendi))))
+      (delete-file file))))
+
+(ert-deftest test-ui-theme-load-invalid-theme-falls-back ()
+  "An invalid persisted theme should disable current themes and load fallback."
+  (let ((file (make-temp-file "ui-theme-invalid-"))
+        (fallback-theme-name "modus-vivendi")
+        (custom-enabled-themes '(old-theme))
+        disabled
+        loaded)
+    (unwind-protect
+        (progn
+          (cj/theme-write-file-contents "missing-theme" file)
+          (let ((theme-file file))
+            (cl-letf (((symbol-function 'disable-theme)
+                       (lambda (theme) (push theme disabled)))
+                      ((symbol-function 'load-theme)
+                       (lambda (theme &optional _no-confirm _no-enable)
+                         (push theme loaded)
+                         (when (eq theme 'missing-theme)
+                           (error "missing theme")))))
+              (cj/load-theme-from-file)))
+          (should (equal disabled '(old-theme)))
+          (should (equal loaded '(modus-vivendi missing-theme))))
+      (delete-file file))))
+
+(ert-deftest test-ui-theme-load-missing-file-loads-fallback ()
+  "A missing theme file should disable current themes and load fallback."
+  (let ((theme-file (expand-file-name "missing-theme" temporary-file-directory))
+        (fallback-theme-name "modus-vivendi")
+        (custom-enabled-themes '(old-theme))
+        disabled
+        loaded)
+    (cl-letf (((symbol-function 'disable-theme)
+               (lambda (theme) (push theme disabled)))
+              ((symbol-function 'load-theme)
+               (lambda (theme &optional _no-confirm _no-enable)
+                 (push theme loaded))))
+      (cj/load-theme-from-file))
+    (should (equal disabled '(old-theme)))
+    (should (equal loaded '(modus-vivendi)))))
+
+(ert-deftest test-ui-theme-load-literal-nil-disables-themes ()
+  "A persisted literal nil should disable current themes and load nothing."
+  (let ((file (make-temp-file "ui-theme-nil-"))
+        (custom-enabled-themes '(old-theme newer-theme))
+        disabled
+        loaded)
+    (unwind-protect
+        (progn
+          (cj/theme-write-file-contents "nil" file)
+          (let ((theme-file file))
+            (cl-letf (((symbol-function 'disable-theme)
+                       (lambda (theme) (push theme disabled)))
+                      ((symbol-function 'load-theme)
+                       (lambda (theme &optional _no-confirm _no-enable)
+                         (push theme loaded))))
+              (cj/load-theme-from-file)))
+          (should (equal disabled '(newer-theme old-theme)))
+          (should-not loaded))
+      (delete-file file))))
+
+(provide 'test-ui-theme-persistence)
+;;; test-ui-theme-persistence.el ends here