test: cover wttrin-debug.el and expand lint to all source files

I added 24 unit tests across six new files for wttrin-debug.el. They cover enable/disable, the debug-log writer, clear-log, show-log, and the mode-line diagnostic dump. That lifts wttrin-debug.el coverage from 27% to 95%, and overall coverage from 84% to 94%. Each function gets Normal / Boundary / Error categories where applicable. Globals like `wttrin-debug` and `wttrin--debug-log` are isolated per test with let-bindings. The dynamic-scope rebinding restores state cleanly at exit.

I expanded the `lint` target to run on all three source files instead of just `wttrin.el`. Checkdoc and elisp-lint run on every file. Package-lint stays scoped to `wttrin.el` because the others aren't standalone packages.

The tricky bit: `elisp-lint-file` re-runs package-lint internally as one of its validators. So the explicit guard alone wasn't enough. The fix binds `elisp-lint-ignored-validators` to include "package-lint" for the secondaries, which suppresses the re-run at the validator level.

I also added `*-autoloads.el` to .gitignore. Eask generates `emacs-wttrin-autoloads.el` during install, and it shouldn't be tracked.

I skipped one function: `wttrin--debug-mode-line-info` is a one-line dispatcher to `debug-wttrin-mode-line`. Testing it would assert the dispatch happened, which only tests Emacs.

8 files changed, 417 insertions, 16 deletions

diff --git a/.gitignore b/.gitignore
index b622a8e..aead5da 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@
 /.coverage/
 /dist/
 *.elc
+*-autoloads.el
diff --git a/Makefile b/Makefile
index 846fdb5..f80a494 100644
--- a/Makefile
+++ b/Makefile
@@ -280,22 +280,29 @@ compile:
 	@echo "[v] Compilation complete"
 
 lint:
-	@echo "Running linters on $(MAIN_FILE)..."
-	@$(EASK_EMACS) \
-		--eval "(progn \
-			(require 'checkdoc nil t) \
-			(require 'package-lint nil t) \
-			(require 'elisp-lint nil t) \
-			(find-file \"$(MAIN_FILE)\") \
-			(when (featurep 'checkdoc) \
-				(message \"-- checkdoc --\") \
-				(checkdoc-current-buffer t)) \
-			(when (featurep 'package-lint) \
-				(message \"-- package-lint --\") \
-				(package-lint-current-buffer)) \
-			(when (featurep 'elisp-lint) \
-				(message \"-- elisp-lint --\") \
-				(elisp-lint-file \"$(MAIN_FILE)\")))" || true
+	@echo "Running linters on source files..."
+	@for src in $(SOURCE_FILES); do \
+		echo "  Linting $$src..."; \
+		$(EASK_EMACS) \
+			--eval "(let ((src \"$$src\") (main \"$(MAIN_FILE)\")) \
+				(require 'checkdoc nil t) \
+				(require 'package-lint nil t) \
+				(require 'elisp-lint nil t) \
+				(find-file src) \
+				(when (featurep 'checkdoc) \
+					(message \"-- checkdoc on %s --\" src) \
+					(checkdoc-current-buffer t)) \
+				(when (and (featurep 'package-lint) (string= src main)) \
+					(message \"-- package-lint on %s --\" src) \
+					(package-lint-current-buffer)) \
+				(when (featurep 'elisp-lint) \
+					(message \"-- elisp-lint on %s --\" src) \
+					(let ((elisp-lint-ignored-validators \
+							(if (string= src main) \
+								elisp-lint-ignored-validators \
+								(cons \"package-lint\" elisp-lint-ignored-validators)))) \
+						(elisp-lint-file src))))" || true; \
+	done
 	@echo "[i] Lint complete (informational)"
 
 # ============================================================================
diff --git a/tests/test-debug-wttrin-disable.el b/tests/test-debug-wttrin-disable.el
new file mode 100644
index 0000000..dc560c3
--- /dev/null
+++ b/tests/test-debug-wttrin-disable.el
@@ -0,0 +1,43 @@
+;;; test-debug-wttrin-disable.el --- Tests for debug-wttrin-disable -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for debug-wttrin-disable.  Verifies the interactive command
+;; clears `wttrin-debug' and is idempotent when already disabled.
+
+;;; 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-debug-wttrin-disable-normal-flips-from-t-to-nil ()
+  "Calling disable when wttrin-debug is t sets it to nil."
+  (let ((wttrin-debug t))
+    (debug-wttrin-disable)
+    (should-not wttrin-debug)))
+
+(ert-deftest test-debug-wttrin-disable-normal-idempotent-when-already-disabled ()
+  "Calling disable when wttrin-debug is already nil leaves it nil."
+  (let ((wttrin-debug nil))
+    (debug-wttrin-disable)
+    (should-not wttrin-debug)))
+
+;;; Boundary Cases
+
+(ert-deftest test-debug-wttrin-disable-boundary-clears-non-boolean-truthy-value ()
+  "Calling disable replaces any truthy value with nil."
+  (let ((wttrin-debug 'verbose))
+    (debug-wttrin-disable)
+    (should-not wttrin-debug)))
+
+(provide 'test-debug-wttrin-disable)
+;;; test-debug-wttrin-disable.el ends here
diff --git a/tests/test-debug-wttrin-enable.el b/tests/test-debug-wttrin-enable.el
new file mode 100644
index 0000000..569547d
--- /dev/null
+++ b/tests/test-debug-wttrin-enable.el
@@ -0,0 +1,43 @@
+;;; test-debug-wttrin-enable.el --- Tests for debug-wttrin-enable -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for debug-wttrin-enable.  Verifies the interactive command
+;; flips `wttrin-debug' to t and is idempotent when already enabled.
+
+;;; 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-debug-wttrin-enable-normal-flips-from-nil-to-t ()
+  "Calling enable when wttrin-debug is nil sets it to t."
+  (let ((wttrin-debug nil))
+    (debug-wttrin-enable)
+    (should (eq wttrin-debug t))))
+
+(ert-deftest test-debug-wttrin-enable-normal-idempotent-when-already-enabled ()
+  "Calling enable when wttrin-debug is already t leaves it t."
+  (let ((wttrin-debug t))
+    (debug-wttrin-enable)
+    (should (eq wttrin-debug t))))
+
+;;; Boundary Cases
+
+(ert-deftest test-debug-wttrin-enable-boundary-overrides-non-boolean-truthy-value ()
+  "Calling enable replaces a non-boolean truthy value with t."
+  (let ((wttrin-debug 'verbose))
+    (debug-wttrin-enable)
+    (should (eq wttrin-debug t))))
+
+(provide 'test-debug-wttrin-enable)
+;;; test-debug-wttrin-enable.el ends here
diff --git a/tests/test-debug-wttrin-mode-line.el b/tests/test-debug-wttrin-mode-line.el
new file mode 100644
index 0000000..437185a
--- /dev/null
+++ b/tests/test-debug-wttrin-mode-line.el
@@ -0,0 +1,79 @@
+;;; test-debug-wttrin-mode-line.el --- Tests for debug-wttrin-mode-line -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for debug-wttrin-mode-line.  This function is a UI-heavy
+;; diagnostic dump, so testing focuses on the two top-level branches:
+;; - When *wttr.in* is missing, no diagnostic buffer is produced.
+;; - When *wttr.in* exists, the diagnostic buffer is created and contains
+;;   the expected section labels.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+(require 'testutil-wttrin)
+
+(require 'wttrin-debug
+         (expand-file-name "wttrin-debug.el"
+                           (file-name-directory (locate-library "wttrin"))))
+
+;;; Setup and Teardown
+
+(defun test-debug-wttrin-mode-line-setup ()
+  "Setup for debug-wttrin-mode-line tests."
+  (when (get-buffer "*wttr.in*")
+    (kill-buffer "*wttr.in*"))
+  (when (get-buffer "*wttrin-mode-debug*")
+    (kill-buffer "*wttrin-mode-debug*")))
+
+(defun test-debug-wttrin-mode-line-teardown ()
+  "Teardown for debug-wttrin-mode-line tests."
+  (when (get-buffer "*wttr.in*")
+    (kill-buffer "*wttr.in*"))
+  (when (get-buffer "*wttrin-mode-debug*")
+    (kill-buffer "*wttrin-mode-debug*")))
+
+;;; Normal Cases
+
+(ert-deftest test-debug-wttrin-mode-line-normal-no-buffer-skips-diagnostic-buffer ()
+  "When the *wttr.in* buffer is absent, no diagnostic buffer is created."
+  (test-debug-wttrin-mode-line-setup)
+  (unwind-protect
+      (progn
+        (debug-wttrin-mode-line)
+        (should-not (get-buffer "*wttrin-mode-debug*")))
+    (test-debug-wttrin-mode-line-teardown)))
+
+(ert-deftest test-debug-wttrin-mode-line-normal-buffer-exists-creates-diagnostic-buffer ()
+  "When the *wttr.in* buffer exists, the diagnostic buffer is created."
+  (test-debug-wttrin-mode-line-setup)
+  (unwind-protect
+      (progn
+        (with-current-buffer (get-buffer-create "*wttr.in*")
+          (wttrin-mode))
+        (debug-wttrin-mode-line)
+        (should (get-buffer "*wttrin-mode-debug*")))
+    (test-debug-wttrin-mode-line-teardown)))
+
+(ert-deftest test-debug-wttrin-mode-line-normal-diagnostic-buffer-contains-section-labels ()
+  "Diagnostic buffer contains the expected section labels."
+  (test-debug-wttrin-mode-line-setup)
+  (unwind-protect
+      (progn
+        (with-current-buffer (get-buffer-create "*wttr.in*")
+          (wttrin-mode))
+        (debug-wttrin-mode-line)
+        (with-current-buffer "*wttrin-mode-debug*"
+          (let ((contents (buffer-string)))
+            (should (string-match-p "Wttrin Mode-Line Debug Info" contents))
+            (should (string-match-p "Buffer:" contents))
+            (should (string-match-p "Major mode:" contents))
+            (should (string-match-p "mode-name variable:" contents))
+            (should (string-match-p "mode-line-format first 5 elements:" contents)))))
+    (test-debug-wttrin-mode-line-teardown)))
+
+(provide 'test-debug-wttrin-mode-line)
+;;; test-debug-wttrin-mode-line.el ends here
diff --git a/tests/test-wttrin--debug-log.el b/tests/test-wttrin--debug-log.el
new file mode 100644
index 0000000..4f4e2ba
--- /dev/null
+++ b/tests/test-wttrin--debug-log.el
@@ -0,0 +1,82 @@
+;;; test-wttrin--debug-log.el --- Tests for wttrin--debug-log -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for wttrin--debug-log.  Verifies that messages are appended
+;; only when `wttrin-debug' is non-nil, that format args are interpolated,
+;; and that entries are timestamped (timestamp . message) cons cells.
+
+;;; 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-log-normal-appends-entry-when-debug-enabled ()
+  "Calling debug-log with debug enabled appends a single entry."
+  (let ((wttrin-debug t)
+        (wttrin--debug-log nil))
+    (wttrin--debug-log "hello")
+    (should (= 1 (length wttrin--debug-log)))))
+
+(ert-deftest test-wttrin--debug-log-normal-interpolates-format-args ()
+  "Format args are passed through `format' before storage."
+  (let ((wttrin-debug t)
+        (wttrin--debug-log nil))
+    (wttrin--debug-log "value=%d name=%s" 42 "foo")
+    (should (string= "value=42 name=foo" (cdar wttrin--debug-log)))))
+
+(ert-deftest test-wttrin--debug-log-normal-prepends-most-recent-entry ()
+  "Most recent entry is at the head of the log (push semantics)."
+  (let ((wttrin-debug t)
+        (wttrin--debug-log nil))
+    (wttrin--debug-log "first")
+    (wttrin--debug-log "second")
+    (should (string= "second" (cdar wttrin--debug-log)))
+    (should (string= "first" (cdadr wttrin--debug-log)))))
+
+(ert-deftest test-wttrin--debug-log-normal-timestamp-has-millisecond-format ()
+  "Timestamp is a string in HH:MM:SS.mmm format."
+  (let ((wttrin-debug t)
+        (wttrin--debug-log nil))
+    (wttrin--debug-log "anything")
+    (should (string-match-p "^[0-9]\\{2\\}:[0-9]\\{2\\}:[0-9]\\{2\\}\\.[0-9]\\{3\\}$"
+                            (caar wttrin--debug-log)))))
+
+;;; Boundary Cases
+
+(ert-deftest test-wttrin--debug-log-boundary-empty-format-string-stores-empty-message ()
+  "An empty format string produces an entry with an empty message."
+  (let ((wttrin-debug t)
+        (wttrin--debug-log nil))
+    (wttrin--debug-log "")
+    (should (= 1 (length wttrin--debug-log)))
+    (should (string= "" (cdar wttrin--debug-log)))))
+
+(ert-deftest test-wttrin--debug-log-boundary-no-format-args-stores-literal-string ()
+  "Calling with only a format string and no args stores it as-is."
+  (let ((wttrin-debug t)
+        (wttrin--debug-log nil))
+    (wttrin--debug-log "literal text with no format directives")
+    (should (string= "literal text with no format directives"
+                     (cdar wttrin--debug-log)))))
+
+;;; Error Cases
+
+(ert-deftest test-wttrin--debug-log-error-no-entry-when-debug-disabled ()
+  "When wttrin-debug is nil, debug-log adds nothing."
+  (let ((wttrin-debug nil)
+        (wttrin--debug-log nil))
+    (wttrin--debug-log "should not appear")
+    (should-not wttrin--debug-log)))
+
+(provide 'test-wttrin--debug-log)
+;;; test-wttrin--debug-log.el ends here
diff --git a/tests/test-wttrin-debug-clear-log.el b/tests/test-wttrin-debug-clear-log.el
new file mode 100644
index 0000000..10e4c21
--- /dev/null
+++ b/tests/test-wttrin-debug-clear-log.el
@@ -0,0 +1,45 @@
+;;; 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
diff --git a/tests/test-wttrin-debug-show-log.el b/tests/test-wttrin-debug-show-log.el
new file mode 100644
index 0000000..e90b2e9
--- /dev/null
+++ b/tests/test-wttrin-debug-show-log.el
@@ -0,0 +1,101 @@
+;;; test-wttrin-debug-show-log.el --- Tests for wttrin-debug-show-log -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for wttrin-debug-show-log.  Verifies the *wttrin-debug-log*
+;; buffer is created with the expected header, entry rendering, and the
+;; reversed (oldest-first) ordering used for human reading.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+(require 'testutil-wttrin)
+
+(require 'wttrin-debug
+         (expand-file-name "wttrin-debug.el"
+                           (file-name-directory (locate-library "wttrin"))))
+
+;;; Setup and Teardown
+
+(defun test-wttrin-debug-show-log-setup ()
+  "Setup for show-log tests."
+  (when (get-buffer "*wttrin-debug-log*")
+    (kill-buffer "*wttrin-debug-log*")))
+
+(defun test-wttrin-debug-show-log-teardown ()
+  "Teardown for show-log tests."
+  (when (get-buffer "*wttrin-debug-log*")
+    (kill-buffer "*wttrin-debug-log*")))
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin-debug-show-log-normal-creates-display-buffer ()
+  "Show-log creates the *wttrin-debug-log* buffer."
+  (test-wttrin-debug-show-log-setup)
+  (unwind-protect
+      (let ((wttrin--debug-log nil))
+        (wttrin-debug-show-log)
+        (should (get-buffer "*wttrin-debug-log*")))
+    (test-wttrin-debug-show-log-teardown)))
+
+(ert-deftest test-wttrin-debug-show-log-normal-header-shows-entry-count ()
+  "Header reflects the number of entries currently in the log."
+  (test-wttrin-debug-show-log-setup)
+  (unwind-protect
+      (let ((wttrin--debug-log '(("00:00:03.000" . "c")
+                                 ("00:00:02.000" . "b")
+                                 ("00:00:01.000" . "a"))))
+        (wttrin-debug-show-log)
+        (with-current-buffer "*wttrin-debug-log*"
+          (should (string-match-p "Total entries: 3" (buffer-string)))))
+    (test-wttrin-debug-show-log-teardown)))
+
+(ert-deftest test-wttrin-debug-show-log-normal-renders-entries-with-timestamps ()
+  "Each entry appears as [timestamp] message in the display."
+  (test-wttrin-debug-show-log-setup)
+  (unwind-protect
+      (let ((wttrin--debug-log '(("12:34:56.789" . "hello world"))))
+        (wttrin-debug-show-log)
+        (with-current-buffer "*wttrin-debug-log*"
+          (should (string-match-p "\\[12:34:56\\.789\\] hello world"
+                                  (buffer-string)))))
+    (test-wttrin-debug-show-log-teardown)))
+
+(ert-deftest test-wttrin-debug-show-log-normal-entries-rendered-oldest-first ()
+  "Storage is newest-first (push); display reverses to oldest-first for reading."
+  (test-wttrin-debug-show-log-setup)
+  (unwind-protect
+      (let ((wttrin--debug-log '(("00:00:03.000" . "third")
+                                 ("00:00:02.000" . "second")
+                                 ("00:00:01.000" . "first"))))
+        (wttrin-debug-show-log)
+        (with-current-buffer "*wttrin-debug-log*"
+          (let* ((contents (buffer-string))
+                 (pos-first (string-match "first" contents))
+                 (pos-second (string-match "second" contents))
+                 (pos-third (string-match "third" contents)))
+            (should pos-first)
+            (should pos-second)
+            (should pos-third)
+            (should (< pos-first pos-second))
+            (should (< pos-second pos-third)))))
+    (test-wttrin-debug-show-log-teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-wttrin-debug-show-log-boundary-empty-log-shows-placeholder ()
+  "Empty log renders the \"No log entries yet\" placeholder."
+  (test-wttrin-debug-show-log-setup)
+  (unwind-protect
+      (let ((wttrin--debug-log nil))
+        (wttrin-debug-show-log)
+        (with-current-buffer "*wttrin-debug-log*"
+          (should (string-match-p "(No log entries yet)" (buffer-string)))
+          (should (string-match-p "Total entries: 0" (buffer-string)))))
+    (test-wttrin-debug-show-log-teardown)))
+
+(provide 'test-wttrin-debug-show-log)
+;;; test-wttrin-debug-show-log.el ends here