Incorrect coverage code w/ TS private arguments

[arcanis]

🐛 Bug Report

The code executed by Jest with --coverage is incorrect when using TS private arguments. It seems to be transpiled as such, which isn't valid because this can only be used after the super call:

class Bar {}

/* istanbul ignore next */
cov_s64sx2cd4.s[0]++;
exports.Foo = class Foo extends Bar {
  constructor(arg) {
    /* istanbul ignore next */
    this.arg = arg;
    cov_s64sx2cd4.f[0]++;
    cov_s64sx2cd4.s[1]++;
    super();
  }
};

Without --coverage it gets transpiled as such:

class Bar {}

exports.Foo = class Foo extends Bar {
  constructor(arg) {
    super();
    this.arg = arg;
  }
};

Interestingly, it works if I "transpile" the construct myself. The generated code becomes:

class Bar {}

/* istanbul ignore next */
cov_s64sx2cd4.s[0]++;
exports.Foo = class Foo extends Bar {
  constructor(arg) {
    /* istanbul ignore next */
    cov_s64sx2cd4.f[0]++;
    cov_s64sx2cd4.s[1]++;
    super();

    /* istanbul ignore next */
    cov_s64sx2cd4.s[2]++;
    this.arg = arg;
  }
};

To Reproduce

Code that triggers the bug:

class Bar {
}

class Foo extends Bar {
    constructor(
        private arg: number,
    ) {
        super();
    }
}

Expected behavior

Should work, but doesn't

Link to repl or repo (highly encouraged)

https://github.com/arcanis/jest-coverage-ts

Run npx envinfo --preset jest

Paste the results here:

  System:
    OS: macOS 10.14.5
    CPU: (8) x64 Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz
  Binaries:
    Node: 12.3.1 - ~/.nodenv/shims/node
    Yarn: 1.16.0 - ~/.nodenv/shims/yarn
    npm: 6.9.0 - ~/.nodenv/shims/npm
  npmPackages:
    jest: ^24.8.0 => 24.8.0

[SimenB]

Is this istanbuljs/istanbuljs#237? If so, it just needs to wait for babel/babel#9610 to be released

[arcanis]

Seems so! I'll close mine as duplicate 👌

[SimenB]

You can try to apply that patch locally and see if it fixes the issue? Seems very much to be the same issue though 🙂

[SimenB]

@arcanis wanna verify with 7.5.0?

[github-actions]

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