Stop plugin tests using private API
Description
Plugin tests at the moment are using private API. This isn't a problem at the moment really, but it will be when they move to bst-plugins-foo. Especially bad is the fact that some things defined in _exceptions are expected as arguments to public API in testing.runcli.
Changes proposed in this merge request:
- Allow access to
ErrorDomain
andLoadErrorReason
through testing. - Add convenience functions to dump projects/elements to testing
- Allow access to _yaml.load() through testing
This merge request, when approved, will close: #1258 (closed)