Wrong path generated in README.txt in sync directory

I started a new merge request, 5457, with a commit using patch from #33.

We should ensure that the file is writable. It is possible that the site has chosen to make the sync directory not writeable.

@alexpott, I added extra validation around this.
On the cannot-write case, nothing is done.

This still needs an update test.

@quietone, I added an update test.
Please notice that the update tests do not really write the config synchronization directory, as the normal install does.
So, instead, I am writing the readme file manually before running the updates.

The set of commits on the merge request are the following.

- ece085606a Issue #2600558 by a_thakur, vsujeetkumar: Wrong path generated in README.txt in sync directory
- 5c3f034701 Rename hook_update_N to be the second 10.2.0 system update
- 12e0cc171c Use a message on the hook_update_N
- b4efa18839 Validate if the readme file can be written
- 02c2c29dd3 Add an update test
- cecfd695f7 Fix indent

Back to NR.

Applied the MR locally, ran the update hook and that ran without issue by checking the README.txt in my sync folder (which current is default)

Update tests were added

Ran test-only feature and got

1) Drupal\Tests\system\Functional\Update\ConfigSyncReadmeUpdateTest::testConfigurationSynchronizationReadmeUpdate
Failed asserting that 'Original content had admin/config/development/configuration/sync as path' does not contain "admin/config/development/configuration/sync".
/builds/issue/drupal-2600558/vendor/phpunit/phpunit/src/Framework/Constraint/Constraint.php:121
/builds/issue/drupal-2600558/vendor/phpunit/phpunit/src/Framework/Constraint/Constraint.php:55
/builds/issue/drupal-2600558/core/modules/system/tests/src/Functional/Update/ConfigSyncReadmeUpdateTest.php:41
/builds/issue/drupal-2600558/vendor/phpunit/phpunit/src/Framework/TestResult.php:728
FAILURES!
Tests: 1, Assertions: 180, Failures: 1.

Issue credits

Just one minor change now this has missed the 10.2 window

Proper status

Updated the MR as per the change request made in #44, thanks!

Small tweak to 10.3 was done.

Added some feedback to the MR

@smustgrave, @larowlan, @alexpott: thanks for the feedback.
@ankithashetty, thanks for the extra fix.

I have added some extra changes around the provided feedback.

- 0a0a1798b6 No operation if readme is not there
- 1b71aa71f6 Replace the URL path instead of rewriting the whole file
- 858815f640 Move new hook_update_N implementation to a new hook_post_update_NAME

Back to NR.

Seems feedback has been addressed

Committed 549b1e3 and pushed to 11.x. Thanks!
Committed caff00d and pushed to 10.2.x. Thanks!

I've removed the update path and test and committed the fix to 10.2.x so new sites are not affected by this.

Automatically closed - issue fixed for 2 weeks with no activity.