Add a first GitHub workflow CI. I expect that the PHP "extensions" list will need to be expanded. But I think that I have to merge first, in order to get the first run. So there is likely to be a followup PR.

1. require PHP 7.1 or later and phpunit 7
2. test on PHP 7.1 through 7.4
3. switch to "standard" php-cs-fixer for code style
4. add phpstan.neon and run on CI at level 1 (which passes)

• cleanup .gitignore
• implement Travis like in skel (separate phpstan job, --prefer-lowest in matrix)
• apply php-cs-fixer changes for tests folder
• move tests into tests/Cache and adjust composer autoload-dev section to fix phpstan:

composer phpstan
> @php vendor/bin/phpstan analyse lib tests
Note: Using configuration file /home/phil/git/sabre-io/cache/phpstan.neon.
 10/10 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%

 ------ ------------------------------------------------------------------- 
  Line   tests/Cache/AbstractCacheTest.php                                  
 ------ ------------------------------------------------------------------- 
         Class Sabre\Cache\AbstractCacheTest was not found while trying to  
         analyse it - autoloading is probably not configured properly.      
 ------ ------------------------------------------------------------------- 

 ------ ----------------------------------------------------------------------- 
  Line   tests/Cache/ApcuTest.php                                               
 ------ ----------------------------------------------------------------------- 
         Class Sabre\Cache\ApcuTest was not found while trying to analyse it -  
         autoloading is probably not configured properly.                       
 ------ ----------------------------------------------------------------------- 

 ------ ----------------------------------------------------------------------- 
  Line   tests/Cache/MemcachedTest.php                                          
 ------ ----------------------------------------------------------------------- 
         Class Sabre\Cache\MemcachedTest was not found while trying to analyse  
         it - autoloading is probably not configured properly.                  
 ------ ----------------------------------------------------------------------- 

 ------ ----------------------------------------------------------------- 
  Line   tests/Cache/MemoryCacheTest.php                                  
 ------ ----------------------------------------------------------------- 
         Class Sabre\Cache\MemoryCacheTest was not found while trying to  
         analyse it - autoloading is probably not configured properly.    
 ------ ----------------------------------------------------------------- 

 [ERROR] Found 4 errors                                                         

Script @php vendor/bin/phpstan analyse lib tests handling the phpstan event returned with error code 1

(I made it the similar pattern to what happens in vobject )

This PR is really an excuse to make the new GitHub workflows run, and get them passing.

1. correct some minor typos
2. add a return to the end of deleteMultiple which was missing (report by code analysis)
3. Setup memcached server and apcu for tests

This makes all 72 unit tests run and pass, like they did with Travis.

The latest php-cs-fixer finds some new things. Code changes were needed in https://github.com/sabre-io/dav/pull/1316 for sabre/dav. We might as well consistently make sure to use at least this version 2.17.1 in all repos so that we are doing consistent code-style checking.

It complains about comments at the end of lines in the class definition. I removed those and wrote some words in the main comment block.

1. sort out variables in .travis.yml for selecting to run php-cs-fixer, phpunit and phpstan
2. Add a matrix entry to run just phpunit on Ubuntu 20.04 "focal" with "nightly" PHP (which is the way to get PHP 8.0 at the moment)
3. When not running php-cs-fixer, explicitly remove it from composer.json (because php-cs-fixer does not yet support PHP 8.0, so composer cannot sort out dependencies if we have PHP 8.0 and php-cs-fixer 2.* together)

Should a release be done to officially record support for PHP 7.4?

(I don't think any real code needed to be touched, so actually the current release would work fine with PHP 7.4)

https://phpunit.de/announcements/phpunit-9.html

2nd commit: In Travis, only bother to report/upload coverage if the job actually runs unit tests with coverage enabled.

On PHP 7.3 it failed just today:

$ ./bin/phpunit --verbose --configuration tests/phpunit.xml.dist

PHPUnit 7.5.20 by Sebastian Bergmann and contributors.

Runtime:       PHP 7.3.14 with Xdebug 2.9.1

Configuration: /home/travis/build/sabre-io/cache/tests/phpunit.xml.dist

.............................FF.........S........................ 65 / 72 ( 90%)

.......                                                           72 / 72 (100%)

Time: 12.07 seconds, Memory: 4.00 MB

There were 2 failures:

1) Sabre\Cache\MemcachedTest::testSetExpire

Failed asserting that null matches expected 'bar'.

/home/travis/build/sabre-io/cache/tests/AbstractCacheTest.php:80

2) Sabre\Cache\MemcachedTest::testSetExpireDateInterval

Failed asserting that null matches expected 'bar'.

/home/travis/build/sabre-io/cache/tests/AbstractCacheTest.php:96

But the same unit tests passed on 7.1 7.3 7.4 ???

It passed when I reran the PHP 7.3 job: https://travis-ci.org/sabre-io/cache/jobs/641984569?utm_medium=notification&utm_source=github_status

So I guess there is a timing issue somewhere? So there is some timing issue with these unit tests.

The APC adapter doesnt implement the interface correctly, it returns directly the result of apcu_store even though the interface calls for boolean result.

Also it includes the trait MultipleTrait even tough it implements them

Traversable type is converted into a array in userland which can be ineffecient for Iterators providing lots of elements.

APCU supports a custom type which can be passed into the functions to let this scenario be handled more efficiently.

http://php.net/manual/en/class.apcuiterator.php