Version
v19.5.0
Platform
Darwin Aris-MacBook-Air.local 22.2.0 Darwin Kernel Version 22.2.0: Fri Nov 11 02:06:26 PST 2022; root:xnu-8792.61.2~4/RELEASE_ARM64_T8112 arm64
Subsystem
No response
What steps will reproduce the bug?
/Users/x/x/repro
├── index.mjs
└── worker.js
// worker.js
console.log("worker::NODE_V8_COVERAGE", process.env.NODE_V8_COVERAGE);// index.mjs
import { Worker } from "worker_threads";
import { existsSync } from "fs";
import { resolve } from "path";
const NODE_V8_COVERAGE = resolve("./coverage");
const worker = new Worker("./worker.js", { env: { NODE_V8_COVERAGE } });
await new Promise((resolve, reject) => {
worker.on("exit", resolve);
worker.on("error", reject);
});
// Check if V8 coverage report was written to file system
console.log("existsSync(NODE_V8_COVERAGE)", existsSync(NODE_V8_COVERAGE));$ rm -rf ./coverage # Just to be sure setup is clean
$ node index.mjs
How often does it reproduce? Is there a required condition?
Always.
What is the expected behavior?
Worker should use options.env.NODE_V8_COVERAGE and output the coverage report there.
What do you see instead?
No coverage report is written. However worker logs process.env.NODE_V8_COVERAGE correctly.
$ rm -rf ./coverage # Just to be sure setup is clean
$ node index.mjs
> worker::NODE_V8_COVERAGE /Users/x/y/repro/coverage
> existsSync(NODE_V8_COVERAGE) false
Worker only outputs coverage report if main thread has process.env.NODE_V8_COVERAGE set. It does not matter what value main thread has. Worker will use the one it was given in options. This is demonstrated below.
If the NODE_V8_COVERAGE is present on main thread, worker will report coverage. The worker.js is seen in ./coverage/<x>.json report.
- const worker = new Worker("./worker.js", { env: { NODE_V8_COVERAGE } });
+ process.env.NODE_V8_COVERAGE = NODE_V8_COVERAGE;
+ const worker = new Worker("./worker.js");$ rm -rf ./coverage # Just to be sure setup is clean
$ node index.mjs
worker::NODE_V8_COVERAGE /Users/x/y/repro/coverage
existsSync(NODE_V8_COVERAGE) true
To make things even more inconsistent, let's try having different values for NODE_V8_COVERAGE in main thread and worker.
const NODE_V8_COVERAGE = resolve("./coverage");
...
+ process.env.NODE_V8_COVERAGE = resolve("./coverage-main-thread"); // This won't be used at all, but there has to be some value in main thread's env for workers to work
const worker = new Worker("./worker.js", { env: { NODE_V8_COVERAGE } });$ rm -rf ./coverage # Just to be sure setup is clean
$ node index.mjs
> worker::NODE_V8_COVERAGE /Users/x/y/repro/coverage
> existsSync(NODE_V8_COVERAGE) true
$ ls
coverage index.mjs worker.js
The main thread's process.env.NODE_V8_COVERAGE is ignored by worker - there is no ./coverage-main-thread directory on file system.
However if main thread's process.env.NODE_V8_COVERAGE is not present, worker won't output coverage at all.
Additional information
It does not matter if worker.js runs takeCoverage():
// worker.js
console.log("worker::NODE_V8_COVERAGE", process.env.NODE_V8_COVERAGE);
+ require("v8").takeCoverage();To summarize:
- Worker does output V8 coverage if main thread has
process.env.NODE_V8_COVERAGE set ✅
- Worker does not output V8 coverage if main thread has no
process.env.NODE_V8_COVERAGE set, and worker is given options.env.NODE_V8_COVERAGE ❌
- Worker outputs coverage to
options.env.NODE_V8_COVERAGE and not to main thread's process.env.NODE_V8_COVERAGE. If main thread's process.env.NODE_V8_COVERAGE is removed, no report is generated. So why is main threads environment variable required to be present? 😕
Version
v19.5.0
Platform
Darwin Aris-MacBook-Air.local 22.2.0 Darwin Kernel Version 22.2.0: Fri Nov 11 02:06:26 PST 2022; root:xnu-8792.61.2~4/RELEASE_ARM64_T8112 arm64
Subsystem
No response
What steps will reproduce the bug?
$ rm -rf ./coverage # Just to be sure setup is clean $ node index.mjsHow often does it reproduce? Is there a required condition?
Always.
What is the expected behavior?
Worker should use
options.env.NODE_V8_COVERAGEand output the coverage report there.What do you see instead?
No coverage report is written. However worker logs
process.env.NODE_V8_COVERAGEcorrectly.Worker only outputs coverage report if main thread has
process.env.NODE_V8_COVERAGEset. It does not matter what value main thread has. Worker will use the one it was given in options. This is demonstrated below.If the
NODE_V8_COVERAGEis present on main thread, worker will report coverage. Theworker.jsis seen in./coverage/<x>.jsonreport.To make things even more inconsistent, let's try having different values for
NODE_V8_COVERAGEin main thread and worker.const NODE_V8_COVERAGE = resolve("./coverage"); ... + process.env.NODE_V8_COVERAGE = resolve("./coverage-main-thread"); // This won't be used at all, but there has to be some value in main thread's env for workers to work const worker = new Worker("./worker.js", { env: { NODE_V8_COVERAGE } });The main thread's
process.env.NODE_V8_COVERAGEis ignored by worker - there is no./coverage-main-threaddirectory on file system.However if main thread's
process.env.NODE_V8_COVERAGEis not present, worker won't output coverage at all.Additional information
It does not matter if
worker.jsrunstakeCoverage():// worker.js console.log("worker::NODE_V8_COVERAGE", process.env.NODE_V8_COVERAGE); + require("v8").takeCoverage();To summarize:
process.env.NODE_V8_COVERAGEset ✅process.env.NODE_V8_COVERAGEset, and worker is givenoptions.env.NODE_V8_COVERAGE❌options.env.NODE_V8_COVERAGEand not to main thread'sprocess.env.NODE_V8_COVERAGE. If main thread'sprocess.env.NODE_V8_COVERAGEis removed, no report is generated. So why is main threads environment variable required to be present? 😕