ert: Add basic explainer for string-equal

* lisp/emacs-lisp/ert.el (ert--explain-string-equal): Add basic
explainer for 'string-equal' based on 'ert--explain-equal'.

diff --git a/lisp/emacs-lisp/ert.el b/lisp/emacs-lisp/ert.el
index 6d867abd7a2717dcd09408b3966ad87ad9dbec6f..e72321f90ffb6716cb9c1bb85f2e63e9a8554ecc 100644 (file)
--- a/lisp/emacs-lisp/ert.el
+++ b/lisp/emacs-lisp/ert.el
@@ -540,6 +540,14 @@ Returns nil if they are."
     (ert--explain-equal-rec a b)))
 (put 'equal 'ert-explainer 'ert--explain-equal)
 
+(defun ert--explain-string-equal (a b)
+  "Explainer function for `string-equal'."
+  ;; Convert if they are symbols.
+  (let ((as (if (symbolp a) (symbol-name a) a))
+        (bs (if (symbolp b) (symbol-name b) b)))
+    (ert--explain-equal-rec as bs)))
+(put 'string-equal 'ert-explainer 'ert--explain-string-equal)
+
 (defun ert--significant-plist-keys (plist)
   "Return the keys of PLIST that have non-null values, in order."
   (cl-assert (zerop (mod (length plist) 2)) t)