refactor(jumper): extract marker-traversal and location-candidates helpers

jumper--location-exists-p and jumper--format-location both opened a marker with the same save-current-buffer/set-buffer/save-excursion/goto-char dance; jumper-jump-to-location and jumper-remove-location shared a verbatim candidate-list cl-loop. Extract jumper--with-marker-at (index fn) and jumper--location-candidates; the four callers delegate. Adds direct coverage of the candidate list.

1 files changed, 52 insertions, 0 deletions

diff --git a/tests/test-jumper--location-candidates.el b/tests/test-jumper--location-candidates.el
new file mode 100644
index 000000000..df095830a
--- /dev/null
+++ b/tests/test-jumper--location-candidates.el
@@ -0,0 +1,52 @@
+;;; test-jumper--location-candidates.el --- Tests for jumper--location-candidates -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; jumper--location-candidates is the (display . index) builder extracted from
+;; the verbatim cl-loop in jumper-jump-to-location and jumper-remove-location.
+;; It composes jumper--format-location (which now goes through the extracted
+;; jumper--with-marker-at).  The wrappers cover it transitively; this exercises
+;; it directly against stored locations.
+
+;;; Code:
+
+(require 'ert)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'jumper)
+
+(ert-deftest test-jumper-location-candidates-one-pair-per-stored-location ()
+  "Normal: one (display . index) pair per stored location, indices in order."
+  (let ((saved-regs jumper--registers)
+        (saved-idx jumper--next-index))
+    (unwind-protect
+        (progn
+          (setq jumper--registers (make-vector jumper-max-locations nil)
+                jumper--next-index 0)
+          (with-temp-buffer
+            (insert "line one\nline two\nline three\n")
+            (goto-char (point-min))
+            (should (integerp (jumper--do-store-location)))   ; index 0
+            (forward-line 2)
+            (should (integerp (jumper--do-store-location)))   ; index 1
+            (let ((cands (jumper--location-candidates)))
+              (should (= (length cands) 2))
+              (should (equal (mapcar #'cdr cands) '(0 1)))
+              (should (stringp (car (nth 0 cands))))
+              (should (stringp (car (nth 1 cands)))))))
+      (setq jumper--registers saved-regs
+            jumper--next-index saved-idx))))
+
+(ert-deftest test-jumper-location-candidates-empty-when-none-stored ()
+  "Boundary: no stored locations yields an empty candidate list."
+  (let ((saved-regs jumper--registers)
+        (saved-idx jumper--next-index))
+    (unwind-protect
+        (progn
+          (setq jumper--registers (make-vector jumper-max-locations nil)
+                jumper--next-index 0)
+          (should (null (jumper--location-candidates))))
+      (setq jumper--registers saved-regs
+            jumper--next-index saved-idx))))
+
+(provide 'test-jumper--location-candidates)
+;;; test-jumper--location-candidates.el ends here