test: explain-text helpers and SM-or-Leitner dispatch

9 ERT tests covering:

- get-explain-text: no :explain: parent returns existing-text,
  parent with :explain: tag adds its body, recursion stops at
  top-level outline depth
- explain-answer-presenter: creates after-string overlay with
  Explanation: prefix, replaces prior overlay on second call
- explain-cleaner: removes the overlay, no-op on missing overlay
- sm-or-leitner: runs SM (via org-drill-again) when pending entries
  exceed leitner-completed, falls through to Leitner otherwise

1 files changed, 161 insertions, 0 deletions

diff --git a/tests/test-org-drill-explain-text-and-leitner.el b/tests/test-org-drill-explain-text-and-leitner.el
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+;;; test-org-drill-explain-text-and-leitner.el --- Tests for explain helpers and leitner dispatch  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for:
+;;
+;; - `org-drill-get-explain-text': walks up the outline collecting body
+;;   text from any parent heading tagged `:explain:'.
+;; - `org-drill-explain-answer-presenter': appends an explanation
+;;   overlay below the entry.
+;; - `org-drill-explain-cleaner': removes the explanation overlay.
+;; - `org-drill-sm-or-leitner': chooses between SM and Leitner
+;;   learning based on the pending entry count.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(require 'org)
+(require 'org-drill)
+
+;;;; Helpers
+
+(defmacro with-org-buffer (content &rest body)
+  (declare (indent 1))
+  `(with-temp-buffer
+     (let ((org-startup-folded nil))
+       (insert ,content)
+       (org-mode)
+       (goto-char (point-min))
+       ,@body)))
+
+;;;; org-drill-get-explain-text
+
+(ert-deftest test-get-explain-text-no-explain-parent-returns-existing-text ()
+  "When no parent has :explain:, returns the existing-text arg unchanged."
+  (with-org-buffer "* Parent\n** Child :drill:\nbody\n"
+    (re-search-forward "^\\*\\* Child")
+    (org-back-to-heading t)
+    (should (equal '("preserved")
+                   (org-drill-get-explain-text '("preserved"))))))
+
+(ert-deftest test-get-explain-text-with-explain-parent-collects-body ()
+  "Parent tagged :explain: contributes its body text to the result."
+  (with-org-buffer "* Parent :explain:
+explain-body
+** Child :drill:
+drill-body
+"
+    (re-search-forward "^\\*\\* Child")
+    (org-back-to-heading t)
+    (let ((result (org-drill-get-explain-text)))
+      (should (listp result))
+      (should (= 1 (length result)))
+      (should (string-match-p "explain-body" (car result))))))
+
+(ert-deftest test-get-explain-text-stops-at-top-level ()
+  "Recursion stops when outline-level reaches 1 (no further parents)."
+  (with-org-buffer "* Top\nbody\n"
+    (org-back-to-heading t)
+    ;; outline-level is 1 → returns existing-text immediately.
+    (should (null (org-drill-get-explain-text)))))
+
+;;;; org-drill-explain-answer-presenter
+
+(ert-deftest test-explain-answer-presenter-creates-overlay-with-explanation ()
+  "Creates an overlay below the entry whose after-string contains the
+collected explanation text."
+  (with-org-buffer "* Parent :explain:
+the-explanation
+** Child :drill:
+the-question
+"
+    (re-search-forward "^\\*\\* Child")
+    (org-back-to-heading t)
+    (setq org-drill-explain-overlay nil)
+    (org-drill-explain-answer-presenter)
+    (should org-drill-explain-overlay)
+    (let ((after-text (overlay-get org-drill-explain-overlay 'after-string)))
+      (should (string-match-p "Explanation:" after-text))
+      (should (string-match-p "the-explanation" after-text)))
+    (delete-overlay org-drill-explain-overlay)
+    (setq org-drill-explain-overlay nil)))
+
+(ert-deftest test-explain-answer-presenter-replaces-existing-overlay ()
+  "Calling twice doesn't accumulate overlays — the prior one is cleared."
+  (with-org-buffer "* Parent :explain:\nA\n** Child :drill:\nQ\n"
+    (re-search-forward "^\\*\\* Child")
+    (org-back-to-heading t)
+    (setq org-drill-explain-overlay nil)
+    (org-drill-explain-answer-presenter)
+    (let ((first-overlay org-drill-explain-overlay))
+      (org-drill-explain-answer-presenter)
+      ;; First overlay is no longer live in the buffer.
+      (should-not (memq first-overlay (overlays-in (point-min) (point-max)))))
+    (delete-overlay org-drill-explain-overlay)
+    (setq org-drill-explain-overlay nil)))
+
+;;;; org-drill-explain-cleaner
+
+(ert-deftest test-explain-cleaner-removes-the-overlay ()
+  (with-org-buffer "* Parent :explain:\nA\n** Child :drill:\nQ\n"
+    (re-search-forward "^\\*\\* Child")
+    (org-back-to-heading t)
+    (setq org-drill-explain-overlay nil)
+    (org-drill-explain-answer-presenter)
+    (should org-drill-explain-overlay)
+    (org-drill-explain-cleaner)
+    (should-not (memq org-drill-explain-overlay
+                      (overlays-in (point-min) (point-max))))
+    (setq org-drill-explain-overlay nil)))
+
+(ert-deftest test-explain-cleaner-no-overlay-no-error ()
+  "Cleaner is safe to call when no overlay exists."
+  (setq org-drill-explain-overlay nil)
+  ;; Should not error.
+  (org-drill-explain-cleaner))
+
+;;;; org-drill-sm-or-leitner
+
+(ert-deftest test-sm-or-leitner-with-pending-entries-runs-again ()
+  "When the prior session has pending entries beyond leitner-completed,
+sm-or-leitner runs the SM (org-drill-again) flow."
+  (let ((again-called nil)
+        (leitner-called nil)
+        (session (org-drill-session)))
+    (oset session new-entries
+          (list (let ((m (make-marker))) (set-marker m 1) m)
+                (let ((m (make-marker))) (set-marker m 1) m)))
+    (oset session start-time (float-time (current-time)))
+    (let ((org-drill-last-session session)
+          (org-drill-leitner-completed 0))
+      (cl-letf (((symbol-function 'org-drill-again)
+                 (lambda () (setq again-called t)))
+                ((symbol-function 'org-drill-leitner)
+                 (lambda (&rest _) (setq leitner-called t)))
+                ((symbol-function 'sit-for) #'ignore)
+                ((symbol-function 'org-drill-map-entries) #'ignore))
+        (org-drill-sm-or-leitner)
+        (should again-called)
+        (should-not leitner-called)))))
+
+(ert-deftest test-sm-or-leitner-no-pending-entries-runs-leitner ()
+  "When there's nothing pending in SM-style, fall through to Leitner."
+  (let ((again-called nil)
+        (leitner-called nil)
+        (session (org-drill-session)))
+    (let ((org-drill-last-session session)
+          (org-drill-leitner-completed 0))
+      (cl-letf (((symbol-function 'org-drill-again)
+                 (lambda () (setq again-called t)))
+                ((symbol-function 'org-drill-leitner)
+                 (lambda (&rest _) (setq leitner-called t)))
+                ((symbol-function 'sit-for) #'ignore)
+                ((symbol-function 'org-drill-map-entries) #'ignore))
+        (org-drill-sm-or-leitner)
+        (should-not again-called)
+        (should leitner-called)))))
+
+(provide 'test-org-drill-explain-text-and-leitner)
+
+;;; test-org-drill-explain-text-and-leitner.el ends here