Rework test to be faster.

[zanerock]

Overview

The test is slow in part (I assume) due to constantly starting new shell processes and re-generating the imports. There's a good chance that if we generate the whole code bundle once at the beginning (which itself, would be a good test) and then execute the sub-tests by still calling shell.exec, but not needing to regenerate the code bundle, we could save some time.

Deliverables

• Rework tests to generate the imported code-bundle in one go.