Added support for merging PDFs.

[enboig]

This way you can add multiple input files and they will be merged in output file.

[DaanDeSmedt]

@enboig - thanks for the addition! 👍

It would be fantastic in order to complete the PR, to foresee :

• public function getInputFile() : string - should also reflect the multiple files change
• add a test to ensure multiple files integrity
• update README.md to reflect files list (merge)

[enboig]

How are tests run?
I tried

$ phpunit tests/PHPGhostscript/PHPGhostscriptTest.php 
PHP Fatal error:  PHPUnit\TextUI\RuntimeException cannot implement PHPUnit\TextUI\Exception - it is not an interface in /usr/share/php/PHPUnit/TextUI/Exception/RuntimeException.php on line 15
PHP Stack trace:
PHP   1. {main}() /usr/bin/phpunit:0
PHP   2. PHPUnit\TextUI\Command::main($exit = *uninitialized*) /usr/bin/phpunit:73
PHP   3. {closure:/usr/share/php/PHPUnit/Autoload.php:32-389}($class = 'PHPUnit\\TextUI\\RuntimeException') /usr/share/php/PHPUnit/TextUI/Command.php:98
PHP   4. require() /usr/share/php/PHPUnit/Autoload.php:387

[DaanDeSmedt]

From within the PHPGhostscript package directory (where the composer.json is located) you can use most basic command phpunit.

The PHPUnit configuration is stored in the phpunit.xml file.

Fore more in-depths, have a look at :

• how-to-use-phpunit-installed-from-composer
• how-create-php-package-part-2-phpunit)
• phpunit-8

[enboig]

Done, I had some problems with gs path (I am using linux).

I changed tests to work on my environment, and undid them before commiting.

[enboig]

I was reticent to change getInputFile() to getInputFiles() for backward compatibility; but as soon as it change return type from string to array it was broken.

Thanks for committing the change.

[DaanDeSmedt]

I've merged and release a 1.1 version including your contributions - and mitigate the getInputFiles() change.

Since the filelist is now a collection, it didn't make much sense to keep compatibility but not respecting the return as a collection.

Thanks for the merge feature 👍!