Zowe Explorer unit test suite to review extenders' API methods

[lauren-li]

To facilitate testing Zowe Explorer extenders for conformance, develop a unit test suite that calls each of the implemented API methods for review.

• Enables reviewers of extender conformance to verify that all methods for the extender's selected ZoweExplorerAPI data provider interface(s) are either implemented or throw exceptions that provide meaningful user messages.
• This helps support the following proposed conformance criteria item:
  • If the extension contributes a new data provider to one of the Zowe Explorer tree browsers, it fully implements one of the Zowe Explorer API interfaces (MVS, JES, and USS), or:
  • If the extension has unimplemented methods, it throws exceptions and provides meaningful user messages