Test with PHP 7.1

[dunglas]

Q	A
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets	n/a
License	MIT
Doc PR	n/a

[teohhanhui]

But why would PHP 7.1 be used with the lowest dependencies? Shouldn't we add another matrix instead?

[dunglas]

@teohhanhui it's a good idea to test the lowest version of dependencies with the highest version of the runtime. It maximises the probability to encounter errors because old versions of libraries are most likely the ones not supporting the last version of PHP.

We can add another line to the matrix but it will slow down the build for no real benefit (IMO). Does it worth it?

[teohhanhui]

It maximises the probability to encounter errors because old versions of libraries are most likely the ones not supporting the last version of PHP.

It maximises the probability of other libraries messing up our tests, and that's not our intention. IMO The lowest dependencies test should use the lowest PHP version (if for no other reason than being realistic).

[dunglas]

It's our responsibility to set correctly the min versions to use. Symfony (and most projects I follow) uses the same strategy.