Test enhancement

[peter279k]

Changed log

• Add php-7.4 version test during Travis CI build.
• Let composer.lock be removed on Git version control and it can avoid caching dependencies.
• Using the PHPUnit ^4.8.36 version to support future PHPUnit versions.
• Using the \PHPUnit\Framework\TestCase namespace to be compatible with future PHPUnit versions.
• Using the assertCount to assert expected count is same as result count.
• Using assertTrue or assertFalse to assert that expected value is true or false.

[sabberworm]

Thanks for the phpunit update. Please update and commit the lock file though.

[sabberworm]

I think the lock file should remain in the repo, otherwise we’ll get different versions on each install.

[peter279k]

Hi @sabberworm, thanks for your reply.

Yes. You're right. And I've reverted this :).