[5.4] Add compat6 behaviour plugin to 5.4 so it is available and enabled when updating to 6.x.

[richard67]

Pull Request for #45336 .

Summary of Changes

This pull request (PR) adds the backwards compatibility (b/c) plugin for Joomla 6 from PR #45336 to the 5.4-dev branch so that the plugin is already available and active on Joomla 5.4 when we update to Joomla 6.

On Joomla 5.4 the plugin does not do anything except of being there and being enabled, so that when we update the code to Joomla 6 it can immediately run with the updated code, and 3rd party extensions which would require that plugin being enabled in 6 will not cause the update to break.

It is the same thing as we did in Joomla 4.4 for the Joomla 5 b/c plugin with PR #41738 .

Testing Instructions

It would be good to have tests not only with MySQL or MariaDB but also with PostgreSQL databases.

Testers please report back which kind(s) of database(s) you have used for your tests.

New installation

Make a new installation.

For the actual result use a current 5.4-dev branch or the latest 5.4 nightly build from here:
https://developer.joomla.org/nightlies/Joomla_5.4.0-alpha1-dev-Development-Full_Package.zip

For the expected result use the patched installation package created by Drone for this PR from here:
https://artifacts.joomla.org/drone/joomla/joomla-cms/5.4-dev/45371/downloads/84332/

After that, log in to the Administrator and check if there is a plugin "Behaviour - Backward Compatibility 6", and if so, check the status of that plugin.

Update

Update a 5.3.0 or a 5.3 nightly build to 5.4.

For the actual result update to the latest 5.4 nightly build using the custom update URL or the downloaded update package from here:
https://developer.joomla.org/nightly-builds.html

For the expected result use the custom update URL or the downloaded patched update package created by Drone for this PR from here:
https://artifacts.joomla.org/drone/joomla/joomla-cms/5.4-dev/45371/downloads/84332/

After that, log in to the Administrator and check if there is a plugin "Behaviour - Backward Compatibility 6", and if so, check the status of that plugin.

Actual result BEFORE applying this Pull Request

There is no plugin "Behaviour - Backward Compatibility 6".

Expected result AFTER applying this Pull Request

There is a plugin "Behaviour - Backward Compatibility 6", which is enabled.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[muhme]

I have tested this item ✅ successfully on 1b86975

#### Testing 5.4 New Installation

Using JBT on MacOS Sequoia 15.4 Apple M3, therefore working in a Docker environment.
This clones the github 5.4-dev branch, applies the 45371 PR patch and runs a Cypress-based Joomla installation.
Checked three of the databases/driver variants:

scripts/create 54 mariadbi joomla-cms-45371         # Using MySQLi driver
scripts/create recreate 54 mysql joomla-cms-45371   # Using PDO driver
scripts/create recreate 54 pgsql joomla-cms-4537

Checked three times, the 'Behaviour - Backward Compatibility 6' is installed and enabled. ✅
(btw. 'Behaviour - Backward Compatibility' is also installed, note it is explicit disabled as JBT installation step).

Testing Update

Using Joomla 5.3.0 release (not the development branch). Checked three different databases/driver variants.
After installation configuring:

• Update Channel: Custom URL
• Minimum Stability: Development
• Custom ULR: https://artifacts.joomla.org/drone/joomla/joomla-cms/5.4-dev/45371/downloads/84301/pr_list.xml

Doing Update to 5.4.0-alpha1-dev+pr.45371 and checked three times, the 'Behaviour - Backward Compatibility 6' is installed and enabled. ✅

scripts/create recreate 5.3.0 mariadb   # Using PDO driver
scripts/create recreate 5.3.0 mysqli    # Using MySQLi driver
scripts/create recreate 5.3.0 pgsql

Verifying System Tests

Without JBT, using local installation with homebrew Apache and mariadb, installing 5.4-dev, applying 45371 PR patch and install Joomla:

git clone https://github.com/joomla/joomla-cms -b 5.4-dev www
cd www
gh pr checkout 45371
composer i
npm ci
# created cypress.config.mjs
npx cypress run --spec tests/System/integration/install/Installation.cy.js

Checked 'Behaviour - Backward Compatibility 6' is existing and enabled. 'Behaviour - Backward Compatibility' is existing and I am wondering it is disabled? But this a different question, I guess.

npm run cypress:run

Joomla System Tests are running without errors with enabled 'Behaviour - Backward Compatibility 6' plugin. ✅

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[richard67]

I've restored @muhme 's test result as the change after that was not relevant for functionality.

[exlemor]

I have tested this item ✅ successfully on 71cfce5

I have tested this in 2 environments: both Updates types successfully! :)

1 a test site which started in J4! era and has been updated all of the way step by step to J5.4dev and

2. a test site which started in J5.2 and has seen every small update until J5.4dev

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45371.}

[richard67]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45371.}