up to now we check some values provided by the DefaultConfigurationCache. This is some kind
of plausibility check, but this is not really a check that the instance did not change.
With the tests as they are now we check in fact for a new instance.
In the free wild it is the duty of libraryResource to provide some resource as text
and it is the duty of readYaml to parse a text (... would also be possible to read
a file instead just parsing text, but that is a different story).
In our setup we just forwarded the resource name in libraryResource and reacted on
that resource name inside read yaml. There was no yaml parsing at all, the yaml 'as
it' was returned.
The approach now is much closer to reality. Library resource now provides the
text 'behind' the resource and yaml parses it. There is now a real yaml parsing.
Read yaml is now not registered explicitly anymore. It is just the readYaml closure
which is registerd by default for our tests.
read yaml rule is a very frequently used rule. But having the rule in the common rules
means we cannot register text or files to that rule, which makes it less handy to work
with yaml files in the tests.
