1 files changed, 122 insertions, 0 deletions
diff --git a/tests/test-wttrin-set-location-from-geolocation.el b/tests/test-wttrin-set-location-from-geolocation.el
new file mode 100644
index 0000000..170d0fb
--- /dev/null
+++ b/tests/test-wttrin-set-location-from-geolocation.el
@@ -0,0 +1,122 @@
+;;; test-wttrin-set-location-from-geolocation.el --- Tests for wttrin-set-location-from-geolocation -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2026 Craig Jennings
+
+;;; Commentary:
+;; Unit tests for the interactive `wttrin-set-location-from-geolocation'
+;; command.  Mocks `wttrin-geolocation-detect' (to invoke the callback
+;; synchronously with a chosen value) and `yes-or-no-p' (to simulate
+;; user consent).  Does not hit the network and does not prompt.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(require 'wttrin)
+(require 'wttrin-geolocation)
+
+;;; Setup and Teardown
+
+(defvar test-wttrin-set-location-from-geolocation--saved-favorite nil
+  "Snapshot of `wttrin-favorite-location' restored in teardown.")
+
+(defun test-wttrin-set-location-from-geolocation-setup ()
+  "Snapshot `wttrin-favorite-location' and clear it for the test."
+  (setq test-wttrin-set-location-from-geolocation--saved-favorite
+        wttrin-favorite-location)
+  (setq wttrin-favorite-location nil))
+
+(defun test-wttrin-set-location-from-geolocation-teardown ()
+  "Restore `wttrin-favorite-location' to its pre-test value."
+  (setq wttrin-favorite-location
+        test-wttrin-set-location-from-geolocation--saved-favorite))
+
+;;; Helpers
+
+(defmacro test-wttrin-set-location--with-detected (location confirm &rest body)
+  "Run BODY with `wttrin-geolocation-detect' returning LOCATION and `yes-or-no-p' returning CONFIRM."
+  (declare (indent 2))
+  `(cl-letf (((symbol-function 'wttrin-geolocation-detect)
+              (lambda (callback) (funcall callback ,location)))
+             ((symbol-function 'yes-or-no-p)
+              (lambda (&rest _) ,confirm)))
+     ,@body))
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin-set-location-from-geolocation-normal-confirm-sets-variable ()
+  "Successful detection followed by user confirmation sets the favorite."
+  (test-wttrin-set-location-from-geolocation-setup)
+  (unwind-protect
+      (progn
+        (test-wttrin-set-location--with-detected "Berkeley, California" t
+          (wttrin-set-location-from-geolocation))
+        (should (string= "Berkeley, California" wttrin-favorite-location)))
+    (test-wttrin-set-location-from-geolocation-teardown)))
+
+(ert-deftest test-wttrin-set-location-from-geolocation-normal-decline-leaves-variable-unchanged ()
+  "Successful detection followed by user declining leaves the favorite untouched."
+  (test-wttrin-set-location-from-geolocation-setup)
+  (setq wttrin-favorite-location "Pre-existing, Place")
+  (unwind-protect
+      (progn
+        (test-wttrin-set-location--with-detected "Berkeley, California" nil
+          (wttrin-set-location-from-geolocation))
+        (should (string= "Pre-existing, Place" wttrin-favorite-location)))
+    (test-wttrin-set-location-from-geolocation-teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-wttrin-set-location-from-geolocation-boundary-unicode-location ()
+  "A Unicode location string round-trips into the favorite variable."
+  (test-wttrin-set-location-from-geolocation-setup)
+  (unwind-protect
+      (progn
+        (test-wttrin-set-location--with-detected "München, Bayern" t
+          (wttrin-set-location-from-geolocation))
+        (should (string= "München, Bayern" wttrin-favorite-location)))
+    (test-wttrin-set-location-from-geolocation-teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-wttrin-set-location-from-geolocation-error-nil-detection-leaves-variable-unchanged ()
+  "When detection returns nil, the favorite variable is not modified."
+  (test-wttrin-set-location-from-geolocation-setup)
+  (setq wttrin-favorite-location "Pre-existing, Place")
+  (unwind-protect
+      (progn
+        (test-wttrin-set-location--with-detected nil t
+          (wttrin-set-location-from-geolocation))
+        (should (string= "Pre-existing, Place" wttrin-favorite-location)))
+    (test-wttrin-set-location-from-geolocation-teardown)))
+
+(ert-deftest test-wttrin-set-location-from-geolocation-error-nil-detection-does-not-prompt ()
+  "When detection returns nil, the user is not prompted for confirmation."
+  (test-wttrin-set-location-from-geolocation-setup)
+  (unwind-protect
+      (let ((prompt-called nil))
+        (cl-letf (((symbol-function 'wttrin-geolocation-detect)
+                   (lambda (callback) (funcall callback nil)))
+                  ((symbol-function 'yes-or-no-p)
+                   (lambda (&rest _) (setq prompt-called t) t)))
+          (wttrin-set-location-from-geolocation))
+        (should-not prompt-called))
+    (test-wttrin-set-location-from-geolocation-teardown)))
+
+(ert-deftest test-wttrin-set-location-from-geolocation-error-detection-failure-shows-message ()
+  "When detection returns nil, the user sees a diagnostic message."
+  (test-wttrin-set-location-from-geolocation-setup)
+  (unwind-protect
+      (let ((messages nil))
+        (cl-letf (((symbol-function 'wttrin-geolocation-detect)
+                   (lambda (callback) (funcall callback nil)))
+                  ((symbol-function 'message)
+                   (lambda (fmt &rest args)
+                     (push (apply #'format fmt args) messages))))
+          (wttrin-set-location-from-geolocation))
+        (should (cl-some (lambda (m) (string-match-p "[Cc]ould not detect" m))
+                         messages)))
+    (test-wttrin-set-location-from-geolocation-teardown)))
+
+(provide 'test-wttrin-set-location-from-geolocation)
+;;; test-wttrin-set-location-from-geolocation.el ends here