Using nyc with ts-mocha

[paulmelnikow]

Hi! Are there any examples for using nyc with ts-mocha? We've just adopted ts-mocha in Shields in badges/shields#3722, and our frontend test coverage stopped working at the same time (at least, the new TypeScript files aren't getting included in the coverage reports, even if I add them to the config).

Shields is a relatively complicated repo and I had to fiddle with our nycrc to get frontend test coverage in the first place.

I found these resources for TS coverage with Istanbul/NYC, but they aren't for ts-mocha:

• https://azimi.me/2016/09/30/nyc-mocha-typescript.1.html
• https://istanbul.js.org/docs/tutorials/typescript/
• https://github.com/john-cheesman/ts-mocha-chai-nyc

Some pointers or an example repo where this is working would be really helpful!

[piotrwitek]

Hey, could you share the error log?

[paulmelnikow]

Hi! The tests run without errors, however there's no mention of the .ts files in the coverage report.

Let me know if you'd like to take it for a spin. I could make a branch with a partial set of changes to the config.

[JimLynchCodes]

hey, so weird. I am also having issues with nyc and ts-mocha. For me, the lines report just shows up with all zeros.

nyc ts-mocha -p ./tsconfig.json ./**/*.test.ts --watch-extensions ts

Output:

 ClosestNumberFinder.getAscendingPairsOfClosestNumbers
    ✓ should return pairs of with the lowest absolute difference.

  1 passing (16ms)

----------|----------|----------|----------|----------|-------------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
----------|----------|----------|----------|----------|-------------------|
All files |        0 |        0 |        0 |        0 |                   |
----------|----------|----------|----------|----------|-------------------|

Are there specific things we need to have in tsconfig or the .nycrc maybe in order for it to read the line coverage correctly?

[JimLynchCodes]

woah, check it out @piotrwitek. It says I am a contributor now! 😆

[juank11memphis]

Hello,

Has anybody found a solution for the issue of running nyc with ts-mocha yet? I am still getting the report with only zeros.

Thanks.

[djorg83]

Try adding the --exit option to the end of your mocha arguments.

[juank11memphis]

Hi @djorg83 I was already using the --exit argument, that does not seems to fix the problem unfortunately.

[ceisele-r]

We are unfortunately experiencing the same issue of only reported zeros with the combination of ts-mocha and ncy - even though we already use ts-mocha .... --exit and have not yet found a solution to it.

[ceisele-r]

Oh well, I have to correct myself. I got it working by:

• Install @istanbuljs/nyc-config-typescript via npm i -D @istanbuljs/nyc-config-typescript
• Add

  "extends": "@istanbuljs/nyc-config-typescript",
  "check-coverage": true,

  to the nyc config

• Execute tests with nyc --reporter=lcov --reporter=text-summary npm run test
• npm test script is as described ts-mocha ... --exit

Now we have the coverage summary in the stdout and the coverage reports being built!

[ceisele-r]

Ok, further to add to my last answer - it only works for us if we put the nyc config in package.json.

If we put it in .nycrc file, it does not work and reports no coverage. But if we put it in package.json, it works.

[mucsi96]

Let me share my experience as well. I got the same issue. Was able to resolve this only adding "extension": [".ts"], to nyc configuration.

Summary:

• no need for --exit in ts-mocha ...
• no need for @istanbuljs/nyc-config-typescript
• no need to put the nyc configuration in package.json

my config in .nycrc.json

{
  "cache": false,
  "extension": [".ts"],
  "check-coverage": true,
  "include": ["src/**"],
  "statements": 90,
  "branches": 90,
  "functions": 95,
  "lines": 90
}

my package.json

{
  "scripts": {
    "test": "ts-mocha test/**/*.test.ts --timeout 10000",
    "test:coverage": "nyc --reporter=html --reporter=text --reporter=text-summary npm test"
  }
}

output

ERROR: Coverage for branches (72.73%) does not meet global threshold (90%)
--------------------|----------|----------|----------|----------|-------------------|
File                |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
--------------------|----------|----------|----------|----------|-------------------|
All files           |    90.86 |    72.73 |    95.35 |       90 |                   |
 additionalLinks.ts |      100 |      100 |      100 |      100 |                   |
 class.ts           |    86.36 |       70 |      100 |    86.36 |          10,19,40 |
 dependencies.ts    |    78.57 |       50 |       75 |    76.92 |          15,16,19 |
 description.ts     |       75 |       50 |      100 |       75 |                 8 |
 enumeration.ts     |    90.91 |       50 |      100 |    90.91 |                10 |
 examples.ts        |      100 |      100 |      100 |      100 |                   |
 function.ts        |    96.15 |       80 |      100 |    95.24 |                42 |
 index.ts           |       85 |    66.67 |       75 |    83.33 |          13,14,23 |
 reflection.ts      |    92.86 |    83.33 |      100 |    92.86 |                21 |
 subSection.ts      |      100 |      100 |      100 |      100 |                   |
 title.ts           |      100 |      100 |      100 |      100 |                   |
 type.ts            |    88.89 |     62.5 |      100 |     87.5 |             13,25 |
 typeInfo.ts        |       80 |       50 |      100 |       80 |                 8 |
 variable.ts        |      100 |      100 |      100 |      100 |                   |
--------------------|----------|----------|----------|----------|-------------------|

=============================== Coverage summary ===============================
Statements   : 90.86% ( 159/175 )
Branches     : 72.73% ( 48/66 )
Functions    : 95.35% ( 41/43 )
Lines        : 90% ( 144/160 )
================================================================================

[juank11memphis]

Thanks a lot @mucsi96 that did the trick for me!! :)

[walterdl]

@mucsi96 it works like a charm!

[EyMaddis]

unfortunately this is not true when using yarn run, I guess yarn may create a new sub shell for every call... When using yarn, the statements count is also way of, I guess it is testing the internals of yarn

[chordmemory]

I'm having mixed results with nyc and ts-mocha. Using similar configs too mucsi96, it seems like any file with typescript syntax is silently failing to be instrumented by nyc, resulting in it missing from the coverage report.