The existing build process tests only builds against unsupported versions of PHP. Going forward we should be building against PHP 8 (and any relevant earlier versions).

The WP build process can be adapted to test the plugin using all PHP versions between 7.1 and 8.2. Note that even 8.0 becomes unsupported before the end of 2023.

However the existing PHP test versions 5.6 and 7.0 are not able to be tested with this process. These software versions went out of support on 31 Dec 2018 and 10 Jan 2019 respectively. Similarly the plugin is unable to be tested with versions of WordPress earlier to WP 5.1 which was released over 4 years ago.

The plugin may work with earlier versions but the build tests with them fail.

Code coverage can be increased to about 70%, mainly by invoking the plugin from within the test suite. This then gets the __construct routine lines included in the coverage counts. Note that these yests need to be done after functional tests are done to avoid issues of multiple instantiations of the plugin classes.