coverage results for typescript are non-deterministic

Link to bug demonstration repository

demo repo: https://github.com/Kosta-Github/ts-nyc-issue

the typescript setup described in nyc-config-typescript has been followed

Expected Behavior

running one of the 2 provided test scripts several times should always result in the same (correct) output/result

Observed Behavior

Sometimes the result looks like this and the generated HTML coverage report looks OK:

-------------|----------|----------|----------|----------|-------------------|
File         |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
-------------|----------|----------|----------|----------|-------------------|
All files    |       80 |       50 |    66.67 |       80 |                   |
 func.ts     |    83.33 |       50 |      100 |    83.33 |                 8 |
 nested_1.ts |      100 |      100 |      100 |      100 |                   |
 nested_2.ts |       50 |      100 |        0 |       50 |                 2 |
-------------|----------|----------|----------|----------|-------------------|

=============================== Coverage summary ===============================
Statements   : 80% ( 8/10 )
Branches     : 50% ( 1/2 )
Functions    : 66.67% ( 2/3 )
Lines        : 80% ( 8/10 )
================================================================================

And sometimes the result looks like this:

-------------|----------|----------|----------|----------|-------------------|
File         |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
-------------|----------|----------|----------|----------|-------------------|
All files    |       40 |       50 |    66.67 |       80 |                   |
 func.ts     |       50 |       50 |      100 |      100 |                 5 |
 nested_1.ts |       50 |      100 |      100 |      100 |                   |
 nested_2.ts |        0 |      100 |        0 |        0 |                 2 |
-------------|----------|----------|----------|----------|-------------------|

=============================== Coverage summary ===============================
Statements   : 40% ( 4/10 )
Branches     : 50% ( 1/2 )
Functions    : 66.67% ( 2/3 )
Lines        : 80% ( 4/5 )
================================================================================

And in this case the generated HTML files contain this error message:

Cannot read property 'start' of undefined
TypeError: Cannot read property 'start' of undefined
    at Object.keys.forEach.stName (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-reports/lib/html/annotator.js:53:31)
    at Array.forEach ()
    at annotateStatements (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-reports/lib/html/annotator.js:49:33)
    at Object.annotateSourceCode (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-reports/lib/html/annotator.js:239:9)
    at HtmlReport.onDetail (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-reports/lib/html/index.js:265:27)
    at LcovReport.(anonymous function) [as onDetail] (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-reports/lib/lcov/index.js:23:23)
    at Visitor.(anonymous function) [as onDetail] (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-lib-report/lib/tree.js:34:30)
    at ReportNode.Node.visit (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-lib-report/lib/tree.js:114:17)
    at getChildren.forEach.child (/Users/kosta/devel/misc/ts-nyc-issue/node_modules/istanbul-lib-report/lib/tree.js:118:15)
    at Array.forEach ()

Troubleshooting steps

• still occurring when I put cache: false in my nyc config

Environment Information

$ npx envinfo@latest --preset nyc

  System:
    OS: macOS 10.14.5
    CPU: (4) x64 Intel(R) Core(TM) i7-5557U CPU @ 3.10GHz
    Memory: 1.20 GB / 16.00 GB
  Binaries:
    Node: 10.16.0 - /usr/local/opt/node@10/bin/node
    Yarn: 1.17.3 - /usr/local/bin/yarn
    npm: 6.10.1 - /usr/local/opt/node@10/bin/npm
  npmPackages:
    nyc: ^14.1.1 => 14.1.1 
    ts-node: ^8.3.0 => 8.3.0 
    typescript: ^3.5.3 => 3.5.3 

[coreyfarrell]

Yes

[coreyfarrell]

I believe to use "all": true you need to configure the require options on nyc instead of mocha. TBH I have not downloaded your repository I’m busy currently but this looks like something I’ve seen with babel transpilation.

CC @JaKXz my knowledge of TS is very limited but I think this might be an issue where the instrumentation for nyc --all is not being processed by ts-node/register where the instrumentation for files required by actual tests is being processed by ts-node/register, causing a mismatch.