test: Add boundary, error, and edge case tests

Added 66 comprehensive tests covering:
- Entry detection with extreme values and Unicode
- SM2 algorithm with boundary conditions
- Workflow error handling with malformed data
- Card types with complex content structures

1 files changed, 345 insertions, 0 deletions

diff --git a/tests/test-card-type-twosided.el b/tests/test-card-type-twosided.el
index cda508f..bda4f79 100644
--- a/tests/test-card-type-twosided.el
+++ b/tests/test-card-type-twosided.el
@@ -214,5 +214,350 @@ Two sides for word translation pairs."
     (should (eq twosided-fn 'org-drill-present-two-sided-card))
     (should (eq simple-fn 'org-drill-present-simple-card))))
 
+;;; Aggressive Edge Cases
+
+(ert-deftest test-card-type-twosided-edge-unicode-in-sides ()
+  "Test two-sided card with Unicode in both sides.
+Unicode characters should be preserved correctly."
+  (let ((content "* Unicode Card :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** English
+
+Hello
+
+** 日本語
+
+こんにちは
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-very-long-side-content ()
+  "Test two-sided card with very long content in sides.
+Should handle large amounts of text without issues."
+  (let* ((long-text (make-string 5000 ?x))
+         (content (format "* Long Sides :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Side A
+
+%s
+
+** Side B
+
+%s
+" long-text long-text)))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-sides-with-lists ()
+  "Test two-sided card with org-mode lists in sides."
+  (let ((content "* Lists Card :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Question
+
+What are primary colors?
+
+** Answer
+
+- Red
+- Blue
+- Yellow
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-sides-with-tables ()
+  "Test two-sided card with org-mode tables in sides."
+  (let ((content "* Table Card :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Question
+
+Temperature conversion?
+
+** Table
+
+| Celsius | Fahrenheit |
+|---------+------------|
+|       0 |         32 |
+|     100 |        212 |
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-sides-with-code-blocks ()
+  "Test two-sided card with source code blocks in sides."
+  (let ((content "* Code Card :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Question
+
+Python hello world?
+
+** Code
+
+#+BEGIN_SRC python
+print(\"Hello, World!\")
+#+END_SRC
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-sides-with-links ()
+  "Test two-sided card with org-mode links in sides."
+  (let ((content "* Links Card :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Term
+
+Emacs
+
+** Definition
+
+A [[https://www.gnu.org/software/emacs/][powerful text editor]].
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-sides-with-formatting ()
+  "Test two-sided card with org-mode text formatting in sides."
+  (let ((content "* Formatted Card :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Question
+
+What is *bold*, /italic/, =code=?
+
+** Answer
+
+These are *org-mode* /text/ =formatting= options.
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-sides-with-tags ()
+  "Test two-sided card where sides have tags.
+Tags on subheadings should not interfere with card."
+  (let ((content "* Card with Tagged Sides :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Question :important:
+
+What is the answer?
+
+** Answer :note:
+
+42
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-nested-subheadings-in-sides ()
+  "Test two-sided card with nested subheadings within sides.
+Nested content should be part of the side."
+  (let ((content "* Nested Content :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Side A
+
+Content A
+
+*** Nested Under A
+
+More details.
+
+** Side B
+
+Content B
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-empty-headings ()
+  "Test two-sided card where heading text is minimal."
+  (let ((content "* Minimal Headings :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** A
+
+Full content for A.
+
+** B
+
+Full content for B.
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-special-characters-in-sides ()
+  "Test two-sided card with special characters in side content."
+  (let ((content "* Special Chars :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Question
+
+What are these: @#$%^&*()?
+
+** Answer
+
+Special programming characters.
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-many-extra-sides ()
+  "Test two-sided card with many subheadings (10+).
+Only first two should be used for presentation."
+  (let ((content "* Many Sides :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Side 1
+
+Content 1
+
+** Side 2
+
+Content 2
+
+** Side 3
+
+Extra
+
+** Side 4
+
+Extra
+
+** Side 5
+
+Extra
+
+** Side 6
+
+Extra
+
+** Side 7
+
+Extra
+
+** Side 8
+
+Extra
+
+** Side 9
+
+Extra
+
+** Side 10
+
+Extra
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (>= (test-card-type-twosided--count-subheadings) 10))))))
+
+(ert-deftest test-card-type-twosided-edge-no-subheadings ()
+  "Test two-sided card with no subheadings at all.
+Card is invalid but should not crash."
+  (let ((content "* No Sides :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+Just main body, no subheadings.
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 0 (test-card-type-twosided--count-subheadings)))))))
+
+(ert-deftest test-card-type-twosided-edge-sides-with-drawers ()
+  "Test two-sided card with drawers in sides.
+Drawers should be preserved."
+  (let ((content "* Drawer Card :drill:
+:PROPERTIES:
+:DRILL_CARD_TYPE: twosided
+:END:
+
+** Side A
+
+:LOGBOOK:
+- Note taken on [2024-01-01]
+:END:
+
+Content A
+
+** Side B
+
+Content B
+"))
+    (test-card-type-twosided--with-card
+     content
+     (lambda ()
+       (should (org-drill-entry-p))
+       (should (= 2 (test-card-type-twosided--count-subheadings)))))))
+
 (provide 'test-card-type-twosided)
 ;;; test-card-type-twosided.el ends here