2 files changed, 178 insertions, 2 deletions
diff --git a/tests/test-wttrin--mode-line-tooltip.el b/tests/test-wttrin--mode-line-tooltip.el
new file mode 100644
index 0000000..b92fb8f
--- /dev/null
+++ b/tests/test-wttrin--mode-line-tooltip.el
@@ -0,0 +1,174 @@
+;;; test-wttrin--mode-line-tooltip.el --- Tests for mode-line tooltip -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025-2026 Craig Jennings
+
+;;; Commentary:
+
+;; Unit tests for wttrin--mode-line-tooltip and dynamic help-echo behavior.
+;; The tooltip should compute age at hover time, not at fetch time, so the
+;; user sees accurate "Updated X ago" text regardless of when they hover.
+
+;;; Code:
+
+(require 'ert)
+(require 'wttrin)
+(require 'testutil-wttrin)
+
+;;; Setup and Teardown
+
+(defun test-wttrin--mode-line-tooltip-setup ()
+  "Setup for mode-line tooltip tests."
+  (testutil-wttrin-setup)
+  (setq wttrin-mode-line-string nil)
+  (setq wttrin--mode-line-cache nil))
+
+(defun test-wttrin--mode-line-tooltip-teardown ()
+  "Teardown for mode-line tooltip tests."
+  (testutil-wttrin-teardown)
+  (setq wttrin-mode-line-string nil)
+  (setq wttrin--mode-line-cache nil))
+
+;;; --------------------------------------------------------------------------
+;;; wttrin--mode-line-tooltip
+;;; --------------------------------------------------------------------------
+
+;;; Normal Cases
+
+(ert-deftest test-wttrin--mode-line-tooltip-normal-minutes-old ()
+  "Cache that is 5 minutes old should report '5 minutes ago'."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (cl-letf (((symbol-function 'float-time) (lambda () 1300.0)))
+        (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+        (let ((tooltip (wttrin--mode-line-tooltip)))
+          (should (string-match-p "5 minutes ago" tooltip))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+(ert-deftest test-wttrin--mode-line-tooltip-normal-hours-old ()
+  "Cache that is 2 hours old should report '2 hours ago'."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (cl-letf (((symbol-function 'float-time) (lambda () 8200.0)))
+        (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+        (let ((tooltip (wttrin--mode-line-tooltip)))
+          (should (string-match-p "2 hours ago" tooltip))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+(ert-deftest test-wttrin--mode-line-tooltip-normal-includes-weather-string ()
+  "Tooltip should include the full weather string so user sees conditions."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (cl-letf (((symbol-function 'float-time) (lambda () 1060.0)))
+        (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+        (let ((tooltip (wttrin--mode-line-tooltip)))
+          (should (string-match-p "Paris" tooltip))
+          (should (string-match-p "Clear" tooltip))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+(ert-deftest test-wttrin--mode-line-tooltip-normal-stale-shows-stale-message ()
+  "Data older than 2x refresh interval should show stale warning."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (let ((wttrin-mode-line-refresh-interval 900))
+        (cl-letf (((symbol-function 'float-time) (lambda () 3000.0)))
+          ;; Age is 2000s, threshold is 2*900=1800 → stale
+          (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+          (let ((tooltip (wttrin--mode-line-tooltip)))
+            (should (string-match-p "Stale" tooltip))
+            (should (string-match-p "fetch failed" tooltip)))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-wttrin--mode-line-tooltip-boundary-just-fetched ()
+  "Cache less than 60 seconds old should say 'just now'."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (cl-letf (((symbol-function 'float-time) (lambda () 1030.0)))
+        (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+        (let ((tooltip (wttrin--mode-line-tooltip)))
+          (should (string-match-p "just now" tooltip))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+(ert-deftest test-wttrin--mode-line-tooltip-boundary-nil-cache ()
+  "When cache is nil, tooltip function should return nil without crashing."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (progn
+        (setq wttrin--mode-line-cache nil)
+        (should-not (wttrin--mode-line-tooltip)))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+(ert-deftest test-wttrin--mode-line-tooltip-boundary-exactly-at-stale-threshold ()
+  "Age exactly at 2x refresh interval should NOT be stale (threshold is >)."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (let ((wttrin-mode-line-refresh-interval 900))
+        (cl-letf (((symbol-function 'float-time) (lambda () 2800.0)))
+          ;; Age is exactly 1800s = 2*900 → NOT stale (> not >=)
+          (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+          (let ((tooltip (wttrin--mode-line-tooltip)))
+            (should (string-match-p "Updated" tooltip))
+            (should-not (string-match-p "Stale" tooltip)))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+;;; --------------------------------------------------------------------------
+;;; Integration: dynamic help-echo
+;;; --------------------------------------------------------------------------
+
+(ert-deftest test-wttrin--mode-line-tooltip-integration-help-echo-is-function ()
+  "After update-display, help-echo should be a function, not a static string."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (cl-letf (((symbol-function 'float-time) (lambda () 1000.0)))
+        (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+        (wttrin--mode-line-update-display)
+        (let ((help-echo (get-text-property 0 'help-echo wttrin-mode-line-string)))
+          (should (functionp help-echo))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+(ert-deftest test-wttrin--mode-line-tooltip-integration-age-updates-over-time ()
+  "Same cache, different times: tooltip should show different ages.
+This is the bug reproduction — previously the tooltip was frozen at 'just now'."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (progn
+        ;; Cache data at time 1000
+        (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+
+        ;; At time 1000: should say "just now"
+        (cl-letf (((symbol-function 'float-time) (lambda () 1000.0)))
+          (wttrin--mode-line-update-display)
+          (let* ((help-echo-fn (get-text-property 0 'help-echo wttrin-mode-line-string))
+                 (tooltip (funcall help-echo-fn nil nil nil)))
+            (should (string-match-p "just now" tooltip))))
+
+        ;; At time 1720 (12 minutes later), WITHOUT re-fetching: should say "12 minutes ago"
+        (cl-letf (((symbol-function 'float-time) (lambda () 1720.0)))
+          (let* ((help-echo-fn (get-text-property 0 'help-echo wttrin-mode-line-string))
+                 (tooltip (funcall help-echo-fn nil nil nil)))
+            (should (string-match-p "12 minutes ago" tooltip)))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+;;; Error Cases
+
+(ert-deftest test-wttrin--mode-line-tooltip-error-cache-cleared-after-display ()
+  "If cache is cleared after display was set, hovering should not crash."
+  (test-wttrin--mode-line-tooltip-setup)
+  (unwind-protect
+      (progn
+        (cl-letf (((symbol-function 'float-time) (lambda () 1000.0)))
+          (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
+          (wttrin--mode-line-update-display))
+        ;; Cache cleared (e.g., by wttrin--mode-line-stop)
+        (setq wttrin--mode-line-cache nil)
+        ;; Hovering over the now-stale mode-line string should not crash
+        (let ((help-echo-fn (get-text-property 0 'help-echo wttrin-mode-line-string)))
+          (should (functionp help-echo-fn))
+          ;; Should return nil or a string, not crash
+          (let ((result (funcall help-echo-fn nil nil nil)))
+            (should (or (null result) (stringp result))))))
+    (test-wttrin--mode-line-tooltip-teardown)))
+
+(provide 'test-wttrin--mode-line-tooltip)
+;;; test-wttrin--mode-line-tooltip.el ends here
diff --git a/tests/test-wttrin--mode-line-update-display.el b/tests/test-wttrin--mode-line-update-display.el
index e23780b..81fbded 100644
--- a/tests/test-wttrin--mode-line-update-display.el
+++ b/tests/test-wttrin--mode-line-update-display.el
@@ -146,7 +146,8 @@
       (cl-letf (((symbol-function 'float-time) (lambda () 1300.0)))
         (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
         (wttrin--mode-line-update-display)
-        (let ((tooltip (get-text-property 0 'help-echo wttrin-mode-line-string)))
+        (let* ((help-echo-fn (get-text-property 0 'help-echo wttrin-mode-line-string))
+               (tooltip (funcall help-echo-fn nil nil nil)))
           (should (string-match-p "Paris" tooltip))
           (should (string-match-p "Updated 5 minutes ago" tooltip))))
     (test-wttrin--mode-line-update-display-teardown)))
@@ -162,7 +163,8 @@
           ;; Data is 2000 seconds old, threshold is 2*900=1800 -> stale
           (setq wttrin--mode-line-cache (cons 1000.0 "Paris: ☀️ +61°F Clear"))
           (wttrin--mode-line-update-display)
-          (let ((tooltip (get-text-property 0 'help-echo wttrin-mode-line-string)))
+          (let* ((help-echo-fn (get-text-property 0 'help-echo wttrin-mode-line-string))
+                 (tooltip (funcall help-echo-fn nil nil nil)))
             (should (string-match-p "Stale" tooltip))
             (should (string-match-p "fetch failed" tooltip)))))
     (test-wttrin--mode-line-update-display-teardown)))