Fix bulk check typing issue

[tstirrat15]

Fixes #187

Note

This is not yet a solution to the problem, but it is a test that demonstrates the problem.

Description

As seen in #187, promisified clients have the wrong types, which means that they disagree with the runtime about the correct invocation. This is likely in part due to how we're typing the promisified clients, and in part due to the clients having multiple overloads for the generated methods.

Changes

• Add some test utilities
• Add a test that demonstrates the issue

Testing

Review.