Not prepending sourceRoot when parsing source maps

[nainslie]

From the v3 source map specification, sourceRoot is:

an optional source root, useful for relocating source files on a server or removing repeated values in the “sources” entry. This value is prepended to the individual entries in the “source” field.

In my workflow I'm generating a single js bundle from individual TypeScript files. Using gulp-sourcemaps I'm getting a source map for a single JS file that looks like

{"version":3,
"sources":["/src/App.ts","/src/common/Capability.ts","/src/common/controllers/AboutController.ts",
... snip approx 60 more files ...],
 "file":"tsbundle.js","sourceRoot":"../.."}

The sourceRoot is being generated relative to the destPath I specified when writing out sourceMaps. The whole gulp task looks like:

gulp.task('tsc', ['template'], function () {
    return tsProject.src()
        .pipe(sourcemaps.init()) // This means sourcemaps will be generated
        .pipe(tsProject())
        .js
        .pipe(sourcemaps.write('.', { destPath: 'www/js', includeContent: false }))
        .pipe(gulp.dest("www/js"));
});

Important to note here is that, although the sources specified in the sourcemap look like absolute paths, once the sourceRoot is prepended (per the spec) they become relative paths.

However, remap-istanbul interprets them as absolute paths and tries to load files like C:\src\App.ts, which don't exist.

I have a fix for this and will put together a pull request shortly.