Global tracing subscriber error on pact-js with Jest when --watch or --watchAll is enabled

[bertrandE]

Software versions

• OS: MacOS 14.6.1
• Pact library: @pact-foundation/pact@15.0.1
• Node Version: Node 22.11.0

Issue Checklist

Please confirm the following:

• I have upgraded to the latest
• I have the read the FAQs in the Readme
• I have triple checked, that there are no unhandled promises in my code and have read the section on intermittent test failures
• I have set my log level to debug and attached a log file showing the complete request/response cycle
• For bonus points and virtual high fives, I have created a reproduceable git repository (see below) to illustrate the problem

Expected behaviour

When running the tests, no error should be shown.

Actual behaviour

When running the tests using Jest / Pact-js, the following error is reported before (or after?) every test:

Failed to initialise global tracing subscriber - a global default trace dispatcher has already been set

The reference implementation has several places where this could come from:
https://github.com/search?q=repo%3Apact-foundation%2Fpact-reference%20set_global_default&type=code

This seems to be linked to the --watch or --watchAll flag as when I run without them, no error is reported.

Note that this does not seem to influence the execution of the tests (they run just as well).

Am I right to assume that this global default trace dispatcher is linked to the telemetry that pact collects and that setting the PACT_DO_NOT_TRACK =true env var should disable it? I tried it without success.

Steps to reproduce

I have gathered a minimal reproductible repo here:
https://github.com/bertrandE/jest-global-tracing-repro/tree/main

Just run npm run test.

The logs of the execution:

 PASS  src/b.pact.jest.ts
  Suite B
    ✓ Test B (349 ms)

Failed to initialise global tracing subscriber - a global default trace dispatcher has already been set
 PASS  src/a.pact.jest.ts
  Suite A
    ✓ Test A (6 ms)

Test Suites: 2 passed, 2 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        1.336 s

Relevant log files

debug.txt