Improve the message when run coverage while there are no tests

[tiendq]

🐛 Bug Report

When you run jest with --coverage but there are no tests, it shows error "Jest: Coverage data for global was not found."

To Reproduce

1. Delete all test files e.g. *.test.js

2. Run jest --config=jest.json --coverage with below configuration in jest.json:

{
  "testEnvironment": "node",
  "coverageThreshold": {
    "global": {
      "branches": 90,
      "functions": 90,
      "lines": 90,
      "statements": -10
    }
  },
  "collectCoverageFrom" : [
    "*.js"
  ]
}

Expected behavior

A simple and clear error like "No tests found", or simply skipping coverage, or coverage report as usual (and failed 100%).

Link to repl or repo (highly encouraged)

https://github.com/Tiendq/lego-part-loader

Run npx envinfo --preset jest

System:
    OS: macOS Sierra 10.12.6
  Binaries:
    Node: 10.0.0 - /usr/local/bin/node
    Yarn: 1.6.0 - /usr/local/bin/yarn
    npm: 5.6.0 - /usr/local/bin/npm
  npmPackages:
    jest: ^22.4.3 => 22.4.3 

[misoguy]

I'd like to try this if no one is on it 😄

[SimenB]

Go for it :)

[misoguy]

I'm looking into this issue and I can't seem to reproduce the issue so I'm quite lost.
I've run jest --config=jest.json --coverage on the repo that @tiendq provided above and got the following message

No tests found
In /Users/jayhwang/Documents/bug-test
  7 files checked.
  testMatch: **/__tests__/**/*.js?(x),**/?(*.)(spec|test).js?(x) - 0 matches
  testPathIgnorePatterns: /node_modules/ - 7 matches
Pattern:  - 0 matches
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

There is no sign of Jest: Coverage data for global was not found.

I also tried it with the master branch of jest and got the following

No tests found
In /Users/jayhwang/Documents/bug-test
  7 files checked.
  testMatch: **/__tests__/**/*.js?(x),**/?(*.)(spec|test).js?(x) - 0 matches
  testPathIgnorePatterns: /node_modules/ - 7 matches
Pattern:  - 0 matches

[SimenB]

You need to include --coverage

[misoguy]

I did include coverage
jest --config=jest.json --coverage

[tiendq]

@misoguy I couldn't reproduce it too :(, I checked package.json history and Jest version is still same.

[zlk89]

I am getting same issue here, my case has one more option: --changedSince=master

[tiendq]

I could reproduce @zlk89 case, it seems that there is something unstable here.

jest --config=jest.json --coverage --changedSince=master

[Oak-V]

I am getting same issue here, my case only in watch mode --watch.

pakage.json

...
  "jest": {
    "transform": {
      "^.+\\.tsx?$": "ts-jest"
    },
    "testRegex": "/tests/.*\\.spec\\.tsx?$",
    "moduleFileExtensions": [
      "ts",
      "tsx",
      "js",
      "jsx",
      "json",
      "node"
    ],
    "collectCoverage": true,
    "coverageDirectory": "coverage",
    "coverageThreshold": {
      "global": {
        "branches": 80,
        "functions": 80,
        "lines": 80,
        "statements": -10
      }
    }
  },
...

bash Jest

$ npx jest --watch

No tests found related to files changed since last commit.
Press `a` to run all tests, or run Jest with `--watchAll`.
----------|----------|----------|----------|----------|-------------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
----------|----------|----------|----------|----------|-------------------|
All files |        0 |        0 |        0 |        0 |                   |
----------|----------|----------|----------|----------|-------------------|
Jest: Coverage data for global was not found.

bash envinfo

$ npx envinfo --preset jest

  System:
    OS: macOS Sierra 10.12.6
    CPU: x64 Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
  Binaries:
    Node: 10.0.0 - /usr/local/bin/node
    Yarn: 1.6.0 - /usr/local/bin/yarn
    npm: 6.0.1 - /usr/local/bin/npm
  npmPackages:
    @types/jest: ^22.2.3 => 22.2.3
    jest: ^22.4.3 => 22.4.3

[zlk89]

@misoguy kindly ask if there is any update on this?

[misoguy]

@zlk89 I'm sorry, lately I didn't really find time... Feel free to take this issue if you'd like, if not I'll try to find time to tackle this issue soon 😄

[tiendq]

I also want to try it too but it won't be done quickly, I'm new to Jest codebase :) and it seems that the issue happens with many cases.

[rickhanlonii]

Here's where that error is thrown, should be able to add the check you need somewhere in that function with a nice explination

[github-actions]

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