Clear-text and progress report not getting generated

[adarshnd14]

Question
I have run mutation test on a JavaScript repository having around 47000 mutants. The clear-text report is not getting shown in the terminal.
Only if I reduce the mutants and run test on specific file with same config, I am able to get the clear-text report in the terminal.

Stryker environment

+-- @stryker-mutator/core@7.0.0
+-- stryker-cli@1.0.1

When I use @stryker-mutator/jest-runner@7.0.0 mutation scan was getting failed so we were using core.

+-- jest@26.6.2

Stryker environment

+-- @stryker-mutator/core@7.0.0
+-- stryker-cli@1.0.1

When I use @stryker-mutator/jest-runner@7.0.0 mutation scan was getting failed so we were using core.

+-- jest@26.6.2

Additional context
Stryker config used for file level scan:

File level test:

Project level test:

[nicojs]

I can see the issue. All mutants result in a timeout, meaning that it took too long for them to resolve, so StrykerJS assumes they resulted in an infinite loop somewhere.

Timeout mutants are logged at debug level, not logged in the clear-text report. See the source code here:

https://github.com/stryker-mutator/stryker-js/blob/master/packages/core/src/reporters/clear-text-reporter.ts#L102-L114

The reason for the timeout mutants is that you are running with 191 (!!) concurrent test runner processes. This is probably much higher than your available cores, resulting in process starvation and the mutants timing out.

As you didn't specify a concurrency in your Stryker config, I assume StrykerJS detects more virtual cores than physically available. You can verify this yourself using node -p 'require("os").cpus().length'. Running Stryker inside your CI with --concurrency 2 or something would solve this.