test: add overlay coverage for cloze hide/show and entry text replacement

19 ERT tests covering the buffer-overlay machinery behind card
presentation:

- org-drill-hide-region / unhide-text: bounds, optional display
  text, no-op on clean buffers, leaves unrelated overlays alone
- org-drill-hide-clozed-text / unhide-clozed-text: hides every
  cloze span with org-drill-cloze-overlay-defaults category, clean
  round-trip
- org-drill-hide-cloze-hints: hides only the ||hint portion when
  present, no-op when absent (locks in the production fix)
- org-drill-replace-entry-text / unreplace-entry-text: covers entry
  body with placeholder string overlay
- org-drill-get-entry-text: returns body text, strips text-properties
  by default

1 files changed, 222 insertions, 0 deletions

diff --git a/tests/test-org-drill-hide-show.el b/tests/test-org-drill-hide-show.el
new file mode 100644
index 0000000..da234c1
--- /dev/null
+++ b/tests/test-org-drill-hide-show.el
@@ -0,0 +1,222 @@
+;;; test-org-drill-hide-show.el --- Tests for cloze-hide / replace-text overlay functions  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for the buffer-overlay machinery that drives card presentation:
+;;
+;; - `org-drill-hide-region': make a single hidden-text overlay
+;; - `org-drill-unhide-text': remove all hidden-text overlays
+;; - `org-drill-hide-clozed-text' / `unhide-clozed-text': hide every
+;;   `[cloze]' span in the buffer (using `org-drill-cloze-overlay-defaults'
+;;   category).  This is what makes the answer disappear when the card
+;;   is presented.
+;; - `org-drill-hide-cloze-hints': hide just the `||hint' tail of each
+;;   cloze span without hiding the rest.
+;; - `org-drill-replace-entry-text' / `unreplace-entry-text': overlay
+;;   the entry body with a placeholder string.
+;;
+;; The user-facing contract: when the card is shown, the answer is
+;; hidden behind an overlay.  When the answer is revealed, every
+;; overlay disappears.  Round-trip cleanliness matters.
+
+;;; Code:
+
+(require 'ert)
+(require 'org)
+(require 'org-drill)
+
+;;;; Helpers
+
+(defmacro with-cloze-buffer (content &rest body)
+  "Run BODY in a temp org buffer with CONTENT, point at start, fontification
+caches refreshed so the cloze regex picks up current delimiter values."
+  (declare (indent 1))
+  `(with-temp-buffer
+     (let ((org-startup-folded nil))
+       (insert ,content)
+       (org-mode)
+       (goto-char (point-min))
+       (setq-local org-drill-cloze-regexp (org-drill--compute-cloze-regexp))
+       ,@body)))
+
+(defun count-overlays-of-category (cat)
+  "Count overlays in current buffer whose `category' property equals 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-hide-region
+
+(ert-deftest test-org-drill-hide-region-creates-one-overlay ()
+  (with-cloze-buffer "Some plain text here."
+    (org-drill-hide-region 6 11)
+    (should (= 1 (count-overlays-of-category 'org-drill-hidden-text-overlay)))))
+
+(ert-deftest test-org-drill-hide-region-respects-given-bounds ()
+  (with-cloze-buffer "Some plain text here."
+    (org-drill-hide-region 6 11)
+    (let ((ovl (car (overlays-at 8))))
+      (should (= 6 (overlay-start ovl)))
+      (should (= 11 (overlay-end ovl))))))
+
+(ert-deftest test-org-drill-hide-region-with-text-shows-replacement ()
+  "When a TEXT arg is supplied, the overlay's `display' shows that string
+instead of being invisible."
+  (with-cloze-buffer "Some plain text here."
+    (org-drill-hide-region 6 11 "[REDACTED]")
+    (let ((ovl (car (overlays-at 8))))
+      (should (equal "[REDACTED]" (overlay-get ovl 'display))))))
+
+(ert-deftest test-org-drill-hide-region-without-text-uses-invisible ()
+  "Without a TEXT arg, the overlay relies on the category's invisible
+property — no `display' string is set."
+  (with-cloze-buffer "Some plain text here."
+    (org-drill-hide-region 6 11)
+    (let ((ovl (car (overlays-at 8))))
+      (should (null (overlay-get ovl 'display))))))
+
+;;;; org-drill-unhide-text
+
+(ert-deftest test-org-drill-unhide-text-removes-hidden-overlays ()
+  (with-cloze-buffer "Some text and more."
+    (org-drill-hide-region 1 5)
+    (org-drill-hide-region 11 15)
+    (should (= 2 (count-overlays-of-category 'org-drill-hidden-text-overlay)))
+    (org-drill-unhide-text)
+    (should (= 0 (count-overlays-of-category 'org-drill-hidden-text-overlay)))))
+
+(ert-deftest test-org-drill-unhide-text-leaves-other-categories-alone ()
+  "`unhide-text' only removes hidden-text-overlay; other categories survive."
+  (with-cloze-buffer "Some text and more."
+    (let ((ovl (make-overlay 1 5)))
+      (overlay-put ovl 'category 'unrelated-overlay))
+    (org-drill-hide-region 11 15)
+    (org-drill-unhide-text)
+    (should (= 0 (count-overlays-of-category 'org-drill-hidden-text-overlay)))
+    (should (= 1 (count-overlays-of-category 'unrelated-overlay)))))
+
+(ert-deftest test-org-drill-unhide-text-on-clean-buffer-is-noop ()
+  (with-cloze-buffer "No overlays here."
+    (org-drill-unhide-text)
+    (should (= 0 (count-overlays-of-category 'org-drill-hidden-text-overlay)))))
+
+;;;; org-drill-hide-clozed-text — full cloze hiding
+
+(ert-deftest test-org-drill-hide-clozed-text-hides-every-cloze ()
+  "Two clozes in the buffer → two cloze-overlay-defaults overlays after hiding."
+  (with-cloze-buffer "Capital of France is [Paris] and Italy is [Rome]."
+    (org-drill-hide-clozed-text)
+    (should (= 2 (count-overlays-of-category 'org-drill-cloze-overlay-defaults)))))
+
+(ert-deftest test-org-drill-hide-clozed-text-no-cloze-no-overlays ()
+  (with-cloze-buffer "Plain prose without any cloze syntax."
+    (org-drill-hide-clozed-text)
+    (should (= 0 (count-overlays-of-category 'org-drill-cloze-overlay-defaults)))))
+
+(ert-deftest test-org-drill-hide-clozed-text-with-hint-still-hides ()
+  "A cloze with a hint `[hidden||hint]' is hidden the same way."
+  (with-cloze-buffer "Capital of France is [Paris||a city of light]."
+    (org-drill-hide-clozed-text)
+    (should (= 1 (count-overlays-of-category 'org-drill-cloze-overlay-defaults)))))
+
+;;;; org-drill-unhide-clozed-text
+
+(ert-deftest test-org-drill-unhide-clozed-text-removes-cloze-overlays ()
+  (with-cloze-buffer "Capital of France is [Paris] and Italy is [Rome]."
+    (org-drill-hide-clozed-text)
+    (should (= 2 (count-overlays-of-category 'org-drill-cloze-overlay-defaults)))
+    (org-drill-unhide-clozed-text)
+    (should (= 0 (count-overlays-of-category 'org-drill-cloze-overlay-defaults)))))
+
+;;;; org-drill-hide-cloze-hints
+
+(ert-deftest test-org-drill-hide-cloze-hints-hides-only-hint-portion ()
+  "On `[hidden||hint]', only the `||hint' portion gets a hidden-text
+overlay — the `[hidden' part stays visible."
+  (with-cloze-buffer "Capital is [Paris||a city of light]."
+    (org-drill-hide-cloze-hints)
+    (should (= 1 (count-overlays-of-category 'org-drill-hidden-text-overlay)))))
+
+(ert-deftest test-org-drill-hide-cloze-hints-no-hint-no-overlay ()
+  "A cloze with no hint section is left alone."
+  (with-cloze-buffer "Capital is [Paris]."
+    (org-drill-hide-cloze-hints)
+    (should (= 0 (count-overlays-of-category 'org-drill-hidden-text-overlay)))))
+
+;;;; Round-trip — show then unhide cleanly
+
+(ert-deftest test-org-drill-cloze-roundtrip-hide-then-unhide-leaves-no-overlays ()
+  "Hiding clozes then unhiding leaves the buffer free of any cloze overlays.
+This is the contract that lets a card be re-shown after the user reveals
+the answer."
+  (with-cloze-buffer "[A] then [B] then [C]."
+    (org-drill-hide-clozed-text)
+    (should (= 3 (count-overlays-of-category 'org-drill-cloze-overlay-defaults)))
+    (org-drill-unhide-clozed-text)
+    (should (= 0 (count-overlays-of-category 'org-drill-cloze-overlay-defaults)))))
+
+;;;; org-drill-replace-entry-text / unreplace-entry-text
+
+(ert-deftest test-org-drill-replace-entry-text-creates-replaced-overlay ()
+  "Replacing entry text adds one `org-drill-replaced-text-overlay'."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\nThe body of the entry.\n* Other heading\n")
+      (org-mode)
+      (goto-char (point-min))
+      (org-drill-replace-entry-text "[hidden]")
+      (should (= 1 (count-overlays-of-category 'org-drill-replaced-text-overlay))))))
+
+(ert-deftest test-org-drill-replace-entry-text-displays-given-string ()
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\nThe body of the entry.\n* Other heading\n")
+      (org-mode)
+      (goto-char (point-min))
+      (org-drill-replace-entry-text "[hidden]")
+      (let ((ovl (cl-find-if
+                  (lambda (o)
+                    (eq 'org-drill-replaced-text-overlay (overlay-get o 'category)))
+                  (overlays-in (point-min) (point-max)))))
+        (should (equal "[hidden]" (overlay-get ovl 'display)))))))
+
+(ert-deftest test-org-drill-unreplace-entry-text-removes-replaced-overlays ()
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\nThe body of the entry.\n* Other heading\n")
+      (org-mode)
+      (goto-char (point-min))
+      (org-drill-replace-entry-text "[hidden]")
+      (should (= 1 (count-overlays-of-category 'org-drill-replaced-text-overlay)))
+      (org-drill-unreplace-entry-text)
+      (should (= 0 (count-overlays-of-category 'org-drill-replaced-text-overlay))))))
+
+;;;; org-drill-get-entry-text
+
+(ert-deftest test-org-drill-get-entry-text-returns-body-text ()
+  "Body text under the heading comes back as the entry text."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\nThis is the body of the question.\n")
+      (org-mode)
+      (goto-char (point-min))
+      (let ((text (org-drill-get-entry-text)))
+        (should (stringp text))
+        (should (string-match-p "body of the question" text))))))
+
+(ert-deftest test-org-drill-get-entry-text-strips-text-properties-by-default ()
+  "Default call returns a string with no text properties.
+With KEEP-PROPERTIES-P nil (the default) the org-mode font-lock
+properties are stripped before the string is returned."
+  (with-temp-buffer
+    (let ((org-startup-folded nil))
+      (insert "* Question :drill:\nThe body.\n")
+      (org-mode)
+      (goto-char (point-min))
+      (let ((text (org-drill-get-entry-text)))
+        (should (null (text-properties-at 0 text)))))))
+
+(provide 'test-org-drill-hide-show)
+
+;;; test-org-drill-hide-show.el ends here