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, 65 insertions, 0 deletions

diff --git a/tests/test-wttrin-fetch-raw-string.el b/tests/test-wttrin-fetch-raw-string.el
new file mode 100644
index 0000000..963fd29
--- /dev/null
+++ b/tests/test-wttrin-fetch-raw-string.el
@@ -0,0 +1,65 @@
+;;; test-wttrin-fetch-raw-string.el --- Tests for wttrin-fetch-raw-string -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for wttrin-fetch-raw-string function.
+;; Tests the public API for fetching weather data by location query.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+(require 'testutil-wttrin)
+
+;;; Setup and Teardown
+
+(defun test-wttrin-fetch-raw-string-setup ()
+  "Setup for fetch-raw-string tests."
+  (testutil-wttrin-setup))
+
+(defun test-wttrin-fetch-raw-string-teardown ()
+  "Teardown for fetch-raw-string tests."
+  (testutil-wttrin-teardown))
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin-fetch-raw-string-normal-builds-correct-url ()
+  "The fetch should use a properly constructed wttr.in URL for the query."
+  (test-wttrin-fetch-raw-string-setup)
+  (unwind-protect
+      (let ((fetched-url nil))
+        (cl-letf (((symbol-function 'wttrin--fetch-url)
+                   (lambda (url _callback) (setq fetched-url url))))
+          (wttrin-fetch-raw-string "Paris" #'ignore)
+          ;; URL should contain wttr.in and the encoded location
+          (should (string-match-p "wttr\\.in" fetched-url))
+          (should (string-match-p "Paris" fetched-url))))
+    (test-wttrin-fetch-raw-string-teardown)))
+
+(ert-deftest test-wttrin-fetch-raw-string-normal-passes-callback-through ()
+  "The user's callback should receive the fetched data."
+  (test-wttrin-fetch-raw-string-setup)
+  (unwind-protect
+      (let ((received-data nil))
+        (cl-letf (((symbol-function 'wttrin--fetch-url)
+                   (lambda (_url callback)
+                     (funcall callback "weather response"))))
+          (wttrin-fetch-raw-string "Paris"
+                                   (lambda (data) (setq received-data data)))
+          (should (equal received-data "weather response"))))
+    (test-wttrin-fetch-raw-string-teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-wttrin-fetch-raw-string-error-nil-query-signals-error ()
+  "Passing nil as query should signal an error (invalid URL construction)."
+  (test-wttrin-fetch-raw-string-setup)
+  (unwind-protect
+      (should-error (wttrin-fetch-raw-string nil #'ignore)
+                    :type 'error)
+    (test-wttrin-fetch-raw-string-teardown)))
+
+(provide 'test-wttrin-fetch-raw-string)
+;;; test-wttrin-fetch-raw-string.el ends here