Add more tests for caliper worker

[tunedev]

Checklist

• A link to the issue/user story that the pull request relates to
• How to recreate the problem without the fix
• Design of the fix
• How to prove that the fix works
• Automated tests that prove the fix keeps on working
• Documentation - any JSDoc, website, or Stackoverflow answers?

Issue/User story

Partially addresses #1606

Steps to Reproduce

Existing issues

• Stack Overflow issues
• GitHub Issues
• Discord history

Design of the fix

Validation of the fix

After this PR: Running the tests in caliper-core the listed %stmts in the code coverage report should tally with the below listed

• caliper-core/lib/worker/worker-message-handler.js: 89.13

Before the PR: Running the tests in caliper-core the listed %stmts in the code coverage report the below listed was what was there before

• caliper-core/lib/worker/worker-message-handler.js: 9.78

Automated Tests

What documentation has been provided for this pull request

[davidkel]

Sorry I think this requires a bit of rework. Please don't fall into the trap that you are writing tests that should pass the current implementation only. The approach should be to write tests of the behaviour you expect from the code and then make sure it passes which could result in a needed code change. These tests should find bugs as well as ensure it's easy to make changes and to check the behaviour remains the same

[davidkel]

Apologies I missed the fact that the worker stops on the first error so we don't need to make the changes to the error handling

[davidkel]

Still some issues I'm afraid

[davidkel]

A few minor things plus ideally we could use some more tests but at least this is more than before

[davidkel]

some final minor comments.

[davidkel]

Thanks @tunedev