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+;;; test-wttrin-debug-clear-log.el --- Tests for wttrin-debug-clear-log -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for wttrin-debug-clear-log.  Verifies the interactive
+;; command empties the debug log alist regardless of prior state.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+(require 'testutil-wttrin)
+
+(require 'wttrin-debug
+         (expand-file-name "wttrin-debug.el"
+                           (file-name-directory (locate-library "wttrin"))))
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin-debug-clear-log-normal-empties-populated-log ()
+  "Clearing a non-empty log leaves it nil."
+  (let ((wttrin--debug-log '(("00:00:01.000" . "one")
+                             ("00:00:02.000" . "two"))))
+    (wttrin-debug-clear-log)
+    (should-not wttrin--debug-log)))
+
+(ert-deftest test-wttrin-debug-clear-log-normal-multiple-calls-stay-empty ()
+  "Calling clear twice in a row leaves the log empty."
+  (let ((wttrin--debug-log '(("00:00:01.000" . "one"))))
+    (wttrin-debug-clear-log)
+    (wttrin-debug-clear-log)
+    (should-not wttrin--debug-log)))
+
+;;; Boundary Cases
+
+(ert-deftest test-wttrin-debug-clear-log-boundary-clearing-already-empty-log ()
+  "Clearing an already-empty log is a no-op and leaves it nil."
+  (let ((wttrin--debug-log nil))
+    (wttrin-debug-clear-log)
+    (should-not wttrin--debug-log)))
+
+(provide 'test-wttrin-debug-clear-log)
+;;; test-wttrin-debug-clear-log.el ends here