Using equal-including-properties to compare # string and propertized string

Question

I'm writing some tests for my first emacs package but am running into an issue to do with asserting that two text properties are the same - one that's created with # and another with propertize:

;; this fails
(ert-deftest equal-properties ()
  (should
   (equal-including-properties
    #("Utils" 0 5 (:annotation nil :candidate "type" :meta nil))
    (propertize "Utils" :annotation nil :candidate "type" :meta nil))))

In the ert runner, the forms look the same as well:

F equal-properties
    (ert-test-failed
     ((should
       (equal-including-properties
        #("Utils" 0 5
          (:meta nil :candidate "type" :annotation nil))
        (propertize "Utils" :annotation nil :candidate "type" :meta nil)))
      :form
      (equal-including-properties
       #("Utils" 0 5
         (:meta nil :candidate "type" :annotation nil))
       #("Utils" 0 5
         (:meta nil :candidate "type" :annotation nil)))
      :value nil))

Any pointers would be much appreciated, I'm sure (/I hope) I've missed something simple!

Answer 1

This is due to Bug#6581 - equal-including-properties uses eq to compare property values, hence your :candidate "type" property string values may compare non-eq. If you byte compile the test code, you might find it works because the compiler coalesces string literals (e.g., Bug#31688).

You could consider using a symbol instead of a string, if that makes sense for your purposes:

#("Utils" 0 5 (:meta nil :candidate type :annotation nil))