@peter279k has added PHPUnit tests. That's almost standard nowdays, so it's a good approach. Thanks for that!

• It looks like the current tests are not fully correct. pngToAvailablImagesProvider and jpgToAvailablImagesProvider does the same thing.

https://github.com/jenstornell/php-image-converter/blob/master/tests/ImageConverterTest.php

More tests needed

• Every format read from (about 4-5 formats)
• Every format save to (about 4-5 formats)
• Test with and without the quality argument (output file size should differ)
• Test to send the quality argument to an image type that does not support it (should be ignored)
• Test unknown path (should throw error)
• Test unkown extension (both from and to)
• Test file permissions on save (should throw error on could not write file)
• Test file with correct filename but with wrong mimetype (should throw error)

@jenstornell, thank you for your concern.

You're right, the data provider is duplicated and I think we can use the one availableImageProvider to collect the image file path for the test cases :).