In case unstashAll is called with a Set containing a null value we get
an ugly message in the log:
Unstash failed: null (Could not instantiate {name=null} for UnstashStep(name: String):
This can be avoided by unstashing only in case we have an ID.
The folder com.sap.piper was created and the corresponding test classes
were not moved. Furthermore, a new UtilsTest class was created when this
test class did already exist, and the same tests were already
implemented, also this new test class uses the lesfurets testing
framework when it is not needed, so this new test class is removed and
the test class that there was before is kept.
Starting point for that refactoring: it turned out that the tests
was not independent. The DefaultValueCache which is a singleton
keeps the status over various tests. Success of test execution depends
on the order test execution.
We have now
* a dedicated rule for resetting the default value cache
* JenkinsConfiguration rule (which already provided facilities for
dealing with the configuration) has been replaced by a readYaml rule.
From the PipelineUnit test framework we get already a handler for
libraryResource, which is also part of the setup of the default
values.
* An auxiliar class which combines the
* JenkinsSetupRule (registers the lib)
* JenkinsReadYamlRule (provides facilities for Yaml parsing)
* JenkinsResetDefaultValueCacheRule (cleans up the DefaultValueCache)
into a rule chain. By using this rule chain we ensure that our
setup OK (piper lib registered, and default config can be setup in
a clean way).
