Deprecate allowing NULL as $edit parameter to drupalPostForm()

Before we remove this, we should trigger E_USER_DEPRECATED in that code block in 8.x

Presumably the second parameter should be type-hinted to array in Drupal 9? Also, I thought we could make changes like this to our test infrastructure without deprecating? So we could just type-hint to an array now...

Making this change to see what explodes :)

Spotted the @todo for this, let's revive this and see what happens.

Fixing failures and improving title.

Missed a couple.

Looks good and will prepare for overall deprecation of drupalPostForm.

Needs a CR (or a portion of the CR deprecating drupalPostForm), deprecation test, and a reroll.

Actually, the deprecation message should suggest to use $this->submitForm straight away, if we are to remove deupalPostForm by D10.

Reroll, still needs tests and a CR.

Added this issue to the overall drupalPostForm deprecation CR, https://www.drupal.org/node/3168858

Rerolled again #22, still needs tests and a CR

+++ b/core/tests/Drupal/Tests/UiHelperTrait.php
@@ -195,6 +195,7 @@ protected function drupalPostForm($path, $edit, $submit, array $options = [], $f
+      @trigger_error('Calling ' . __METHOD__ . ' with $edit set to NULL is deprecated in drupal:9.1.0 and will be disallowed in drupal:10.0.0. See https://www.drupal.org/node/xxxxxxx', E_USER_DEPRECATED);

This needs to be adjusted to reflect the URL of the CR, https://www.drupal.org/node/3168858.

We need a simple deprecation test, so to check that when the method is called with NULL for the $edit argument, the deprecation error is actually triggered.

EDIT: also, the deprecation message format is not compliant to the standard format.

Updated the URL of the CR.
@mondrake, I am not sure how it is not compliant to the standard format, please give more info.
Also, i have found out that the use of UiHelperTrait::drupalPostForm() is deprecated now so shouldn't we include a deprecation message regarding that?

@sarvjeetsingh the deprecation of UiHelperTrait::drupalPostForm() is not yet live, so let's wait for #3166543: Deprecate UiHelperTrait::drupalPostForm, keep deprecation silenced that adds the that.

Once that is in, the deprecation message could be:

'Calling ' . __METHOD__ . ' with $edit set to NULL is deprecated in drupal:9.1.0 and the method is removed in drupal:10.0.0. Use $this->submitForm() instead. See https://www.drupal.org/node/3168858

Parent is in now. We can work on this now.

@mondrake, Thanks for the suggestion. I have changed the deprecation message as per the above suggestion.
please review.

please ignore the last comment i.e #30. Here is the updated patch.
please review
Thanks!

#31 looks good but we still need a test.

Added a test, added () to the deprecated method name, removed the @todo for this issue.

Thanks!

Committed a60fbb6 and pushed to 9.1.x. Thanks!