test: add 50 tests for untested functions; fix nil crash in save-debug-data

Add 11 new test files covering wttrin--save-debug-data,
wttrin--buffer-cache-refresh, wttrin--mode-line-stop,
wttrin--mode-line-start, wttrin-query, wttrin-requery-force,
wttrin-mode-line-click, wttrin-mode-line-force-refresh,
wttrin-fetch-raw-string, wttrin-clear-cache, and wttrin-requery.

Fix bug in wttrin--save-debug-data where nil raw-string caused
(insert nil) crash — reachable when debug mode is on and fetch fails.

Refactor wttrin-requery: extract wttrin--requery-location so the
core kill-buffer-and-query logic is testable without mocking
completing-read.

267 tests total (was 217), all passing.

1 files changed, 152 insertions, 0 deletions

diff --git a/tests/test-wttrin-requery.el b/tests/test-wttrin-requery.el
new file mode 100644
index 0000000..e643a34
--- /dev/null
+++ b/tests/test-wttrin-requery.el
@@ -0,0 +1,152 @@
+;;; test-wttrin-requery.el --- Tests for wttrin-requery -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for wttrin--requery-location and wttrin-requery.
+;; wttrin--requery-location holds the core logic (kill buffer, query new location).
+;; wttrin-requery is the interactive wrapper that adds completing-read.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+(require 'testutil-wttrin)
+
+;;; Setup and Teardown
+
+(defun test-wttrin-requery-setup ()
+  "Setup for requery tests."
+  (testutil-wttrin-setup)
+  (when (get-buffer "*wttr.in*")
+    (kill-buffer "*wttr.in*")))
+
+(defun test-wttrin-requery-teardown ()
+  "Teardown for requery tests."
+  (testutil-wttrin-teardown)
+  (when (get-buffer "*wttr.in*")
+    (kill-buffer "*wttr.in*")))
+
+;;; --------------------------------------------------------------------------
+;;; wttrin--requery-location (core logic)
+;;; --------------------------------------------------------------------------
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin--requery-location-normal-kills-existing-buffer ()
+  "Requerying should kill the existing *wttr.in* buffer before opening a new one."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((old-buffer (get-buffer-create "*wttr.in*")))
+        (cl-letf (((symbol-function 'wttrin-query) (lambda (_loc) nil)))
+          (wttrin--requery-location "Tokyo")
+          ;; Old buffer should be dead
+          (should-not (buffer-live-p old-buffer))))
+    (test-wttrin-requery-teardown)))
+
+(ert-deftest test-wttrin--requery-location-normal-queries-new-location ()
+  "Requerying should fetch weather for the newly specified location."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((queried-location nil))
+        (cl-letf (((symbol-function 'wttrin-query)
+                   (lambda (loc) (setq queried-location loc))))
+          (wttrin--requery-location "Berlin, DE")
+          (should (equal queried-location "Berlin, DE"))))
+    (test-wttrin-requery-teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-wttrin--requery-location-boundary-no-existing-buffer ()
+  "Requerying when no weather buffer exists should still query the new location."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((queried-location nil))
+        ;; Ensure no buffer exists
+        (should-not (get-buffer "*wttr.in*"))
+        (cl-letf (((symbol-function 'wttrin-query)
+                   (lambda (loc) (setq queried-location loc))))
+          (wttrin--requery-location "Paris")
+          (should (equal queried-location "Paris"))))
+    (test-wttrin-requery-teardown)))
+
+(ert-deftest test-wttrin--requery-location-boundary-unicode-location ()
+  "Requerying with unicode characters should pass them through unchanged."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((queried-location nil))
+        (cl-letf (((symbol-function 'wttrin-query)
+                   (lambda (loc) (setq queried-location loc))))
+          (wttrin--requery-location "Zürich, CH")
+          (should (equal queried-location "Zürich, CH"))))
+    (test-wttrin-requery-teardown)))
+
+;;; --------------------------------------------------------------------------
+;;; wttrin-requery (interactive wrapper)
+;;; --------------------------------------------------------------------------
+
+(ert-deftest test-wttrin-requery-normal-uses-selected-location ()
+  "The interactive command should pass the user's completing-read selection
+to the core requery function."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((requeried-location nil))
+        (cl-letf (((symbol-function 'completing-read)
+                   (lambda (_prompt _collection &rest _args) "London, GB"))
+                  ((symbol-function 'wttrin--requery-location)
+                   (lambda (loc) (setq requeried-location loc))))
+          (wttrin-requery)
+          (should (equal requeried-location "London, GB"))))
+    (test-wttrin-requery-teardown)))
+
+(ert-deftest test-wttrin-requery-normal-offers-default-locations ()
+  "Completing-read should be called with wttrin-default-locations as candidates."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((offered-collection nil)
+            (wttrin-default-locations '("Paris" "London" "Tokyo")))
+        (cl-letf (((symbol-function 'completing-read)
+                   (lambda (_prompt collection &rest _args)
+                     (setq offered-collection collection)
+                     "Paris"))
+                  ((symbol-function 'wttrin--requery-location)
+                   (lambda (_loc) nil)))
+          (wttrin-requery)
+          (should (equal offered-collection '("Paris" "London" "Tokyo")))))
+    (test-wttrin-requery-teardown)))
+
+(ert-deftest test-wttrin-requery-boundary-single-default-prefills ()
+  "When only one default location exists, it should be pre-filled in the prompt."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((initial-input nil)
+            (wttrin-default-locations '("Solo City")))
+        (cl-letf (((symbol-function 'completing-read)
+                   (lambda (_prompt _collection _predicate _require-match init &rest _args)
+                     (setq initial-input init)
+                     "Solo City"))
+                  ((symbol-function 'wttrin--requery-location)
+                   (lambda (_loc) nil)))
+          (wttrin-requery)
+          (should (equal initial-input "Solo City"))))
+    (test-wttrin-requery-teardown)))
+
+(ert-deftest test-wttrin-requery-boundary-multiple-defaults-no-prefill ()
+  "When multiple default locations exist, nothing should be pre-filled."
+  (test-wttrin-requery-setup)
+  (unwind-protect
+      (let ((initial-input 'not-called)
+            (wttrin-default-locations '("Paris" "London")))
+        (cl-letf (((symbol-function 'completing-read)
+                   (lambda (_prompt _collection _predicate _require-match init &rest _args)
+                     (setq initial-input init)
+                     "Paris"))
+                  ((symbol-function 'wttrin--requery-location)
+                   (lambda (_loc) nil)))
+          (wttrin-requery)
+          (should-not initial-input)))
+    (test-wttrin-requery-teardown)))
+
+(provide 'test-wttrin-requery)
+;;; test-wttrin-requery.el ends here