`node --inspect-brk jest --runInBand --watch` doesn't stop on breakpoint or debugger statement.

🐛 Bug Report

node --inspect-brk jest --runInBand --watch
doesn’t stop on breakpoints or debugger statement whereas
node --inspect-brk jest --runInBand
will (no --watch flag)

Noe: It is using ts-jest 23.0.0

jest.config.js

module.exports = {
    globals: {
        "ts-jest": {
            skipBabel: true,
            enableTsDiagnostics: true,
            disableSourceMapSupport: true
        }
    },
    roots: [
        "<rootDir>/src",
        "<rootDir>/tests"
    ],
    transform: {
        "^.+\\.tsx?$": "ts-jest"
    },
    testRegex: "(/tests/.*.(test|spec)).ts$",
    moduleFileExtensions: [
        "js",
        "ts",
        "json",
        "node"
    ],
    setupTestFrameworkScriptFile: "jest-extended",
    verbose: true
};

Expected behavior

I would expect debugging to work with --watch

Run npx envinfo --preset jest

it errors with

(node:2536) UnhandledPromiseRejectionWarning: TypeError: Cannot read property '1' of null

node --version
v10.0.0

jest version
23.4.0

Thanks

[jamietre]

I started having trouble again after downgrading to 23.1.0, and after pulling some hair out I got things to work reliably by using --no-cache when invoking Jest. This also seems to solve the problem with the latest Jest release too. It’s not clear to me why just downgrading Jest to the version that had been working reliably before didn’t work, but there are so many moving parts that have changed in last few weeks (VS Code version, typescript, jest, ts-jest) I assume there are other things involved.

I tried the following:

jest --inspect --watch

Breakpoints are unverified. Debugging doesn’t work at all

jest --clearCache
jest --inspect --watch

Breakpoints are verified. Stops on breakpoints the first run only. After changing something resulting in tests restarting, vscode still shows verified breakpoints, but the debugger doesn’t work any more.

jest --no-cache --inspect --watch

Seems to work reliably.

So there’s something wrong with the way sourcemaps are cached, apparently, and it isn’t just old/invalid cached information lying around from an older version of something, since clearing the cache only results in it working once.

[ravihugo]

Ran into this, took about 5 hours thinking my VSCode was malfunctioning. If anyone else has a workflow of running jest in watch mode, then using VSCode to “Attach by Process ID”, I recommend modifying your command line to:

jest --watch --no-cache --runInBand