Errorneous coverage skipped report

[sramam]

Please use the template provided below, when reporting bugs:

Expected Behavior

This coverage report has a missing line of coverage. In fact, it's only the trailing semi-colon
that get's reported as having been skipped. This is after the reversing of a source-map to TypeScript.

Unsure this is a problem with nyc, istanbul or the sourcemap reverse mapping.

Observed Behavior

https://coveralls.io/builds/14286562/source?filename=src%2Findex.ts#L20

Bonus Points! Code (or Repository) that Reproduces Issue

git clone https://github.com/tufan-io/data-check
npm i
npm run build
open coverage/index.html 

Navigate to coverage/index.ts.html to see the issue.

Forensic Information

Operating System: the operating system you observed the issue on.
Similar issue observed on OSX and ubuntu.

Environment Information: information about your project's environment, see instructions below:

1. run the following script:

sh -c 'node --version; npm --version; npm ls' > output.txt

2. share a gist with the contents of output.txt.

https://gist.github.com/sramam/3d7543fb7444f2f95ec05a2abc4770ef

[bcoe]

You're correct, looks like it's a missing single branch (the semicolon) rather than the line itself.

The problem appears to be as follows:

_this = _super.call(this, msg) || this;

typescript represents a call to super() like so ☝️, so || this will never execute. @DanielRosenwasser any thoughts on this subject? It would be nice for folks to be able to collect coverage for this scenario -- is there another way the above logic could be implemented, such that coverage is possible?

[DanielRosenwasser]

Check out microsoft/TypeScript#13029; the bottom comment by @ben8p seems to mention this Webpack plugin: https://www.npmjs.com/package/ts-es5-istanbul-coverage

Though admittedly that might perfectly help.

[sramam]

thanks for the pointer @DanielRosenwasser. Looks like emitting es5 code exposes the issue - and emitting es6 hides it.

Since there is not much anyone can do, will update tsconfig.json and pretend the issue went away!
Linking here in case others stumble upon the issue.