How to generate report for active node server?

• Version: 16.18.0
• Platform: Ubuntu 20.04 x86_64 GNU/Linux

Hi, I want to use c8 for checking code coverage for my typescript based node server. My use case is:

1. Frontend will have test scripts which will try to cover maximum APIs.
2. We want to start server in usual way along with c8, with command similar to c8 node --loader ts-node/esm app.ts.
3. Now when the frontend tests gets completed, I want to somehow generate the code coverage reports for the server.

Issue: Right now from what I have read till now, I need to gracefully exit the server using process.exit(0) post which c8 generates the report. But for doing this, it would require to exposing an API which calls process.exit(). This temporary solution works but it doesn’t seem to be ideal way. I tried using kill {PID} commands and usual CTRL + C to end the server but none of them works. Am I missing something or is there any better way to generate report?

[cion-yatindra]

Hi @olivierodo , For my node server, i created an api as

import v8 from 'v8';

.... server setup ...
 const app = express(); 
app.post('/coverage', async (req, res)=>{
        ... some authentication here or in middleware ....
        v8.takeCoverage();
        v8.stopCoverage();
        res.sendStatus(200);
} );

Run server as c8 node app.js. Then start testing from frontend (my use case). Call this /coverage api at end of testing directly from frontend. In server terminal, run c8 report.

After calling this API, the v8 code coverage JSON is generated at directories mentioned in c8 config.

Let me know if you need more details.

[olivierodo]

@cion-yatindra There is multiple issue related to the same topic, actually the issue is not coming from c8, its coming from how nodejs manage the flag NODE_V8_COVERAGE , you can refer to this issue: https://github.com/nodejs/node/issues/29896

Now related to your use case what i would suggest is to use c8 programmatically and build a test launcher that will spin up your server through a child process. Then when your tests are finished you can send a kill signal to your app running in the child process that would then close your server gracefully. I’ll be happy to share in detail how to do if you want to 😁.