Windows: Undefined path resolution behaviour for project (and it parts) located within directory junction links

[ghost]

Expected Behavior

Use of nyc --all mocha should collect coverage data for src directory only, once for each file (tested or not doesn't matter).

Observed Behavior

Instead, with junction links as part of project path, coverage data collected for:

• each tested file (as should be);
• each file in src folder (results in duplicates of already listed tested files with 0% coverage);
• each file in test folder (which is plain wrong, as test folder not in coverage interest paths by default).

Everything referred to as junctions was made like this cmd: mklink /j junction D:\junction
D:\junction is junction origin (real folder), C:\junction is junction link.
Note, that including/excluding coverage paths for nyc do nothing at all, --all flag becomes useless as consequence.

Temporary solutions

1. Move project or it parts within junction links to non-junction structure;
2. Access project folder through junction origins (cannot be achieved for part of project).

Bonus Points! Code (or Repository) that Reproduces Issue

Sample structure and contents in gist suffice to serve the case (nevertheless, reproduced same stuff on several of other projects).

Assuming project structure of:

folder or junction
+-- src
| +-- a.js
| `-- b.js
`-- test
  `-- a.js

If nyc --all mocha used in plain folder, everything works as expected:

PS C:\folder> npm run cover

> buggy@1.0.0 cover C:\folder
> nyc --all mocha

  dummy a test
    √ should be

  1 passing (9ms)

----------|----------|----------|----------|----------|----------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
----------|----------|----------|----------|----------|----------------|
All files |       50 |      100 |       50 |       50 |                |
 a.js     |      100 |      100 |      100 |      100 |                |
 b.js     |        0 |      100 |        0 |        0 |            1,2 |
----------|----------|----------|----------|----------|----------------|

If nyc --all mocha used on directory path within junction link:

PS C:\junction> npm run cover

> buggy@1.0.0 cover C:\junction
> nyc --all mocha

  dummy a test
    √ should be

  1 passing (20ms)

----------|----------|----------|----------|----------|----------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
----------|----------|----------|----------|----------|----------------|
All files |    63.64 |      100 |       60 |    63.64 |                |
 src      |    33.33 |      100 |    33.33 |    33.33 |                |
  a.js    |        0 |      100 |        0 |        0 |            1,2 |
  a.js    |      100 |      100 |      100 |      100 |                |
  b.js    |        0 |      100 |        0 |        0 |            1,2 |
 test     |      100 |      100 |      100 |      100 |                |
  a.js    |      100 |      100 |      100 |      100 |                |
----------|----------|----------|----------|----------|----------------|

If nyc --all mocha used in junction origin (source of junction on D volume):

PS D:\junction> npm run cover

> buggy@1.0.0 cover D:\junction
> nyc --all mocha

  dummy a test
    √ should be

  1 passing (19ms)

----------|----------|----------|----------|----------|----------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
----------|----------|----------|----------|----------|----------------|
All files |       50 |      100 |       50 |       50 |                |
 a.js     |      100 |      100 |      100 |      100 |                |
 b.js     |        0 |      100 |        0 |        0 |            1,2 |
----------|----------|----------|----------|----------|----------------|

The most interesting case -- if nyc --all mocha used in project with src as junction link:

C:\folder>npm run cover

> buggy@1.0.0 cover C:\folder
> nyc --all mocha

  dummy a test
    √ should be

  1 passing (13ms)

--------------|----------|----------|----------|----------|----------------|
File          |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
--------------|----------|----------|----------|----------|----------------|
All files     |    33.33 |      100 |    33.33 |    33.33 |                |
 folder/src   |        0 |      100 |        0 |        0 |                |
  a.js        |        0 |      100 |        0 |        0 |            1,2 |
  b.js        |        0 |      100 |        0 |        0 |            1,2 |
 junction/src |      100 |      100 |      100 |      100 |                |
  a.js        |      100 |      100 |      100 |      100 |                |
--------------|----------|----------|----------|----------|----------------|

Note that cases of project path and src junction links differs greatly.

Forensic Information

Operating System: Windows 10 ver.1607
Environment Information:

Output located at same gist

[bcoe]

@ChantOfAnAnt thank you for the bug report; I think the underlying issue will be in this library here:

https://github.com/istanbuljs/istanbuljs/tree/master/packages/test-exclude

would you mind reopening an issue there? would also greatly appreciate any help you can provide digging into things -- we should be able to add a few new failing test cases to test-exclude.

[ghost]

@bcoe thanks for investigating! As advised, will reopen this as issue on test-exclude in spare time.