testdouble incompatible with coverage tools?

[joebowbeer]

Description

Observing problems using testdouble and nyc in the same project.

Issue

I have a small es6 Javascript project that uses testdouble with a mocha test runner. mocha works fine, but nyc mocha is flakey.

When coverage fails, I see transformation error messages in the console output and the coverage report is empty. If I comment-out the td code in my tests and re-run test coverage, then coverage works and will continue to work until I change the code-under-test, at which point the instrumentation fails again.

I couldn't find any projects where testdouble was used with code coverage, so I converted my project to use rewiremock and coverage worked reliably.

Environment

• node -v output: v8.9.4
• npm -v output: 6.1.0
• npm ls testdouble version: 3.8.1

Example Repo

This project might be useful in repro'ing the issue:

https://github.com/jamestalmage/__demo-nyc-with-proxyquire

[searls]

Could you provide a reproduction that uses testdouble? I've definitely seen tdjs used in projects with coverage before, so I'm dubious that this is a testdouble.js issue.

For example, the library itself uses nyc for coverage and it makes ample use of td.replace in the unit test suite, but still shows accurate coverage readings AFAICT:

=============================== Coverage summary ===============================
Statements   : 97.86% ( 959/980 )
Branches     : 94.12% ( 336/357 )
Functions    : 94.31% ( 232/246 )
Lines        : 98.07% ( 913/931 )
================================================================================

Closing until we can get a reproduction case to test with