validate if hook is a function, not a symbol

conner-tests.el

@@ -205,10 +205,12 @@
    (should-error (conner--validate-command-plist '(:name "name" :command "test" :type "invalidtype")))
    (should-error (conner--validate-command-plist '(:name "name" :command "test" :type "compile" :workdir notstring)))
    (should-error (conner--validate-command-plist '(:name "name" :command "test" :type "compile" :environment notlist)))
-   (should-error (conner--validate-command-plist '(:name "name" :command "test" :type "compile" :hook "not a symbol!")))
+   (should-error (conner--validate-command-plist '(:name "name" :command "test" :type "compile" :hook "not a function!")))
    (should-error (conner--validate-command-plist '(:name "name" :command "test" :type "compile" :silent "not a boolean")))
    (should (eq (conner--validate-command-plist '(:name "name" :command symbol :type "compile")) nil))
-   (should (eq (conner--validate-command-plist '(:name "name" :command "test" :type "compile")) nil))))
+   (should (eq (conner--validate-command-plist '(:name "name" :command "test" :type "compile")) nil))
+   (should (eq (conner--validate-command-plist '(:name "name" :command "hook symbol" :type "compile" :hook car)) nil))
+   (should (eq (conner--validate-command-plist '(:name "name" :command "hook lambda" :type "compile" :hook (lambda () t))) nil))))
 
 (ert-deftest conner-test-hooks ()
   (with-temp-env

conner.el

@@ -185,9 +185,9 @@ If Projectile is available, it defaults to it.  Otherwise, it uses
     (when (not (or (listp (plist-get plist :environment))
                    (not (plist-get plist :environment))))
       (user-error "Environment is not a list"))
-    (when (not (or (symbolp (plist-get plist :hook))
+    (when (not (or (functionp (plist-get plist :hook))
                    (not (plist-get plist :hook))))
-      (user-error "Hook is not a symbol"))
+      (user-error "Hook is not a function"))
     (when (not (booleanp (plist-get plist :silent)))
       (user-error "Silent is not a boolean"))))