Ensure use of PHPUnit installed by composer

[jtpalmer]

Description

Changes tests scripts so that they explicitly use the phpunit command installed by composer.

Motivation and Context

The travis scripts set the PATH to include the composer vendor directory, but there is no guarantee that a developer running the tests scripts will do the same or that they will not have a different version of PHPUnit installed elsewhere in their PATH. These changes ensure that the phpunit that is installed in the vendor directory will be used.

There may be a better way to do this, or we may not want to do it at all, so I'm open to discussion. I do think we should do something to make sure that it's easy for developers running these scripts on the command line to know the correct version of PHPUnit is being used.

Tests performed

Ran updated tests scripts on the command line.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project as found in the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[tyearke]

LGTM. Reducing the potential for inconsistency outweighs the convenience of using a global install, especially when obtaining the required version is just a one-line command.

[jpwhite4]

Sadly, we also need to make this change in all of the other sub module repositories too.