source maps do no respect sourceRoot

[Toxicable]

Under the build tool I am using .ts files do not live next to .js files, therefore we use sourceRoot to point the source maps at the correct source dir.

This line here: https://github.com/istanbuljs/v8-to-istanbul/blob/master/lib/v8-to-istanbul.js#L40

this.path = relativeTo(rawSourceMap.sourcemap.sources[0], this.path)

fails to resolve that logic, we've had to modify it to be

this.path = join(rawSourceMap.sourcemap.sourceRoot, rawSourceMap.sourcemap.sources[0])

for it to be able to resolve sourceRoot's correctly

[bcoe]

@Toxicable what is sourceRoot by default? wondering if we're safe to always use the logic you shared above, or whether we should make it conditional on the value of sourceRoot being set?

[bcoe]

will happily take a patch for this 😄

[Toxicable]

@bcoe usually it's empty string by default.
Will look at how we can combine that logic, but otherwise a conditional should work fine.
I just want to make sure the changes here actually conform to how source maps are meant to be read

[bcoe]

we need to also make sure that relative paths populated in sourceRoot take into account process.cwd() when determining the final path, see: #39

To add an additional pain point, it seems that some sourceMap instrumenters sometimes add the filename in sourceRoot, so we need to be mindful to strip this out when determining the relative path.

I think for a path forward:

• lib/pathutils.js should be updated to handle these edge-cases, rather than using join directly (as is currently the case).
• the c8 test suite should be run with the updated version of v8-to-istanbul before releasing it.

[bcoe]

@Toxicable mind checking if this is fixed in the latest release? I did some reworking around how we handled path resolution, in an effort to make it closer to Source Map V3.

[Toxicable]

Whops, sorry for not checking back in here sooner.
Looks like it handles sourceRoot fine now, thanks!