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alex-seville / blanket

blanket.js is a simple code coverage library for javascript. Designed to be easy to install and use, for both browser and nodejs.
http://blanketjs.org
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Coverage for hoisted vars #568

Open ryasmi opened 7 years ago

ryasmi commented 7 years ago

It doesn't look like this repository is updated much these days unfortunately and this might be a tricky problem to solve, but it's something to be aware of. This is especially a problem if you have a compiler that generates code with var definitions at the bottom of functions like TypeScript currently does.

Blanket Version 1.1.9

Steps to reproduce Create a function like this:

function foobar() {
  a = 10;
  return a;
  var a;
};

Create a test that this function returns 10.

Expected Behaviour I'd expect Blanket to report that the line var a; is covered because it gets hoisted to the top of the function.

Actual Behaviour Blanket reports that the line var a; is not covered.

alex-seville commented 7 years ago

The repository is not been actively (or passively) maintained.

The code coverage is based on lines executed, and since the variable declaration occurs after a return statement, it is never executed. Strictly speaking, blanket is accurate that the line isn't executed, regardless of any hoisting side-effect.

IMO, this is a weird way to handle variable declarations. But more to the point, Blanket would need to find a JS parser that handles the hoisting in order to support something like this.

ryasmi commented 7 years ago

Ok, no worries.

Yeah, I can see that it doesn't technically get executed.

Yeah I agree, it is a weird way to handle the variable declarations, I think the TypeScript compiler is being fixed. No worries, I had a feeling this would be tricky one to resolve in Blanket.

Thanks for taking the time to respond Alex. I hope you've had or having a good weekend 👍