test: add list-utility, hide-comments/drawers, and Leitner promotion coverage

17 ERT tests covering:

- org-drill-swap: distinct indices, same-index no-op, end-to-start
- org-drill-shuffle: preserves element multiset, empty list, singleton
- org-drill-pop-random: removes-one, nil-on-empty, empties singleton
- org-drill-hide-comments: per-line overlay, no-op on comment-free buffer
- org-drill-hide-drawers: PROPERTIES drawer, multiple drawers, no-op
  on drawer-free entry
- org-drill-leitner-promote: box-N → box-(N+1), graduation at box 5
  (with and without org-drill-leitner-promote-to-drill-p flag)

1 files changed, 175 insertions, 0 deletions

diff --git a/tests/test-org-drill-utilities-and-leitner.el b/tests/test-org-drill-utilities-and-leitner.el
new file mode 100644
index 0000000..cc0157c
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+++ b/tests/test-org-drill-utilities-and-leitner.el
@@ -0,0 +1,175 @@
+;;; test-org-drill-utilities-and-leitner.el --- Tests for list utils, hide helpers, Leitner promote  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for a grab-bag of small helpers:
+;;
+;; - `org-drill-swap' / `org-drill-shuffle': in-place list utilities
+;; - `org-drill-pop-random': macro that removes a random element
+;; - `org-drill-hide-comments' / `org-drill-hide-drawers': overlay hiders
+;;   for buffer noise the user shouldn't see during a drill
+;; - `org-drill-leitner-promote': move a card forward in the Leitner
+;;   box system, including the special "graduate to drill" jump at box 5
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(require 'org)
+(require 'org-drill)
+
+;;;; Helpers
+
+(defun count-overlays-of-category (cat)
+  (let ((n 0))
+    (dolist (ovl (overlays-in (point-min) (point-max)))
+      (when (eql cat (overlay-get ovl 'category))
+        (cl-incf n)))
+    n))
+
+;;;; org-drill-swap
+
+(ert-deftest test-org-drill-swap-normal-distinct-indices ()
+  "Swapping indices 0 and 2 in (a b c d) gives (c b a d)."
+  (let ((lst (list 'a 'b 'c 'd)))
+    (org-drill-swap lst 0 2)
+    (should (equal '(c b a d) lst))))
+
+(ert-deftest test-org-drill-swap-same-index-is-noop ()
+  "Swapping an index with itself leaves the list unchanged."
+  (let ((lst (list 'a 'b 'c)))
+    (org-drill-swap lst 1 1)
+    (should (equal '(a b c) lst))))
+
+(ert-deftest test-org-drill-swap-end-and-start ()
+  (let ((lst (list 1 2 3 4 5)))
+    (org-drill-swap lst 0 4)
+    (should (equal '(5 2 3 4 1) lst))))
+
+;;;; org-drill-shuffle
+
+(ert-deftest test-org-drill-shuffle-preserves-element-set ()
+  "After shuffling, the multiset of elements is unchanged."
+  (let* ((original '(1 2 3 4 5 6 7 8 9 10))
+         (shuffled (org-drill-shuffle (copy-sequence original))))
+    (should (equal (sort (copy-sequence shuffled) #'<)
+                   original))))
+
+(ert-deftest test-org-drill-shuffle-empty-list-is-empty ()
+  (should (null (org-drill-shuffle nil)))
+  (should (equal '() (org-drill-shuffle (list)))))
+
+(ert-deftest test-org-drill-shuffle-single-element-unchanged ()
+  (should (equal '(42) (org-drill-shuffle (list 42)))))
+
+;;;; org-drill-pop-random (macro)
+
+(ert-deftest test-org-drill-pop-random-removes-one-element ()
+  (let ((lst (list 'a 'b 'c 'd)))
+    (let ((popped (org-drill-pop-random lst)))
+      (should (memq popped '(a b c d)))
+      (should (= 3 (length lst)))
+      (should-not (memq popped lst)))))
+
+(ert-deftest test-org-drill-pop-random-on-nil-returns-nil ()
+  (let ((lst nil))
+    (should (null (org-drill-pop-random lst)))))
+
+(ert-deftest test-org-drill-pop-random-on-singleton-empties-list ()
+  (let ((lst (list 'only)))
+    (should (eq 'only (org-drill-pop-random lst)))
+    (should (null lst))))
+
+;;;; org-drill-hide-comments
+
+(ert-deftest test-org-drill-hide-comments-hides-each-comment-line ()
+  "Each `^#' comment line gets its own hidden-text overlay."
+  (with-temp-buffer
+    (insert "# first comment\n# second comment\nactual body\n")
+    (goto-char (point-min))
+    (org-drill-hide-comments)
+    (should (= 2 (count-overlays-of-category 'org-drill-hidden-text-overlay)))))
+
+(ert-deftest test-org-drill-hide-comments-no-comments-no-overlays ()
+  (with-temp-buffer
+    (insert "no comments here\njust regular text\n")
+    (goto-char (point-min))
+    (org-drill-hide-comments)
+    (should (= 0 (count-overlays-of-category 'org-drill-hidden-text-overlay)))))
+
+;;;; org-drill-hide-drawers
+
+(ert-deftest test-org-drill-hide-drawers-hides-properties-drawer ()
+  "PROPERTIES drawer becomes a hidden-text overlay during drilling."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\n:PROPERTIES:\n:ID: x\n:END:\nbody\n")
+      (org-mode)
+      (goto-char (point-min))
+      (org-drill-hide-drawers)
+      (should (>= (count-overlays-of-category 'org-drill-hidden-text-overlay) 1)))))
+
+(ert-deftest test-org-drill-hide-drawers-handles-multiple-drawers ()
+  "Multiple drawers each get an overlay."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\n:PROPERTIES:\n:ID: x\n:END:\n:LOGBOOK:\nentry\n:END:\nbody\n")
+      (org-mode)
+      (goto-char (point-min))
+      (org-drill-hide-drawers)
+      (should (>= (count-overlays-of-category 'org-drill-hidden-text-overlay) 2)))))
+
+(ert-deftest test-org-drill-hide-drawers-no-drawer-no-overlay ()
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\nbody only\n")
+      (org-mode)
+      (goto-char (point-min))
+      (org-drill-hide-drawers)
+      (should (= 0 (count-overlays-of-category 'org-drill-hidden-text-overlay))))))
+
+;;;; org-drill-leitner-promote
+
+(ert-deftest test-org-drill-leitner-promote-non-graduating-increments-box ()
+  "Promotion from box 1 → 2, 2 → 3, etc.  No tag change, just a property bump."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :leitner:\n:PROPERTIES:\n:DRILL_LEITNER_BOX: 1\n:END:\n")
+      (org-mode)
+      (goto-char (point-min))
+      (org-drill-leitner-promote 1)
+      (should (equal "2" (org-entry-get (point) "DRILL_LEITNER_BOX")))
+      ;; Tags unchanged.
+      (should (member "leitner" (org-get-tags nil t)))
+      (should-not (member "drill" (org-get-tags nil t))))))
+
+(ert-deftest test-org-drill-leitner-promote-from-box-5-graduates-to-drill ()
+  "Promotion from box 5 toggles `leitner' off and (with the flag) `drill' on."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :leitner:\n:PROPERTIES:\n:DRILL_LEITNER_BOX: 5\n:END:\n")
+      (org-mode)
+      (goto-char (point-min))
+      (let ((org-drill-leitner-promote-to-drill-p t)
+            (org-drill-leitner-completed 0))
+        (org-drill-leitner-promote 5)
+        (should-not (member "leitner" (org-get-tags nil t)))
+        (should (member "drill" (org-get-tags nil t)))
+        (should (= 1 org-drill-leitner-completed))))))
+
+(ert-deftest test-org-drill-leitner-promote-from-box-5-without-promote-flag ()
+  "Without the promote-to-drill flag, only `leitner' tag is removed."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :leitner:\n:PROPERTIES:\n:DRILL_LEITNER_BOX: 5\n:END:\n")
+      (org-mode)
+      (goto-char (point-min))
+      (let ((org-drill-leitner-promote-to-drill-p nil)
+            (org-drill-leitner-completed 0))
+        (org-drill-leitner-promote 5)
+        (should-not (member "leitner" (org-get-tags nil t)))
+        (should-not (member "drill" (org-get-tags nil t)))
+        (should (= 1 org-drill-leitner-completed))))))
+
+(provide 'test-org-drill-utilities-and-leitner)
+
+;;; test-org-drill-utilities-and-leitner.el ends here