test: add gloss-core test suite (red phase)

The commit lands eight per-function test files and a shared testutil. 32 tests across Normal/Boundary/Error categories cover the public API (lookup, save, list, find-buffer-position) and the internals that need observable behavior tests (mtime invalidation, corrupt-file resilience, alphabetical insert, first-call file creation).

All 32 fail with void-function on the gloss-core symbols. That is the intended red-phase signal. The next commit lands the implementation that turns them green.

testutil-gloss provides a with-temp-glossary macro. It binds gloss-file to a temp file, resets the cache before and after, and cleans up the visiting buffer.

1 files changed, 49 insertions, 0 deletions

diff --git a/tests/test-gloss-core--invalidate-on-mtime.el b/tests/test-gloss-core--invalidate-on-mtime.el
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+++ b/tests/test-gloss-core--invalidate-on-mtime.el
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+;;; test-gloss-core--invalidate-on-mtime.el --- Tests for cache mtime invalidation -*- lexical-binding: t -*-
+
+;; SPDX-License-Identifier: GPL-3.0-or-later
+
+;;; Commentary:
+;; Tests that the cache reloads when `gloss-file' is edited out-of-band.
+
+;;; Code:
+
+(require 'ert)
+(require 'gloss-core)
+(require 'testutil-gloss)
+
+(ert-deftest test-gloss-core-invalidate-on-mtime-new-content-detected ()
+  "Normal: out-of-band edit + later lookup sees the new content."
+  (gloss-test--with-temp-glossary gloss-test--sample-content
+    ;; Prime cache.
+    (should (gloss-core-lookup "anaphora"))
+    ;; Append a new entry directly to disk.
+    (with-temp-buffer
+      (insert-file-contents gloss-file)
+      (goto-char (point-max))
+      (insert "\n* hapax\n:PROPERTIES:\n:SOURCE:   manual\n:ADDED:    2026-04-28\n:END:\nA word used only once in a corpus.\n")
+      (write-region (point-min) (point-max) gloss-file))
+    ;; Force mtime change to be visible (1-second granularity on some FSes).
+    (set-file-times gloss-file (time-add (current-time) 5))
+    ;; Lookup detects the mtime change and reloads.
+    (let ((entry (gloss-core-lookup "hapax")))
+      (should entry)
+      (should (string-match-p "used only once" (plist-get entry :body))))))
+
+(ert-deftest test-gloss-core-invalidate-on-mtime-unchanged-uses-cache ()
+  "Boundary: unchanged mtime — two consecutive lookups both succeed."
+  (gloss-test--with-temp-glossary gloss-test--sample-content
+    (should (gloss-core-lookup "anaphora"))
+    (should (gloss-core-lookup "anaphora"))))
+
+(ert-deftest test-gloss-core-invalidate-on-mtime-deleted-file-clears-cache ()
+  "Error: file deleted out-of-band — subsequent lookup returns nil."
+  (gloss-test--with-temp-glossary gloss-test--sample-content
+    (should (gloss-core-lookup "anaphora"))
+    (when-let ((buf (find-buffer-visiting gloss-file)))
+      (with-current-buffer buf (set-buffer-modified-p nil))
+      (kill-buffer buf))
+    (delete-file gloss-file)
+    (should-not (gloss-core-lookup "anaphora"))))
+
+(provide 'test-gloss-core--invalidate-on-mtime)
+;;; test-gloss-core--invalidate-on-mtime.el ends here