Some tests not skipped in incremental mode.

[mkizka]

Summary
Some tests run each time in incremental mode. I expect the tests to be skipped on the second run.

The tests like:

test.each`
  x    | y    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${2} | ${4}
`("add($x, $y) = $expected", ({ x, y, expected }) => {
  expect(add(x, y)).toBe(expected);
});

When such a test exists, stryker shows Tests: 1 files changed (+2 -0) even though I haven't changed any tests.

The cause seems to be that each test has the same start position. This code removes tests with the same start position.

Reproduction steps:

$ git clone https://github.com/mkizka/stryker-js-jest-each
$ cd stryker-js-jest-each
$ yarn
$ yarn stryker run --incremental
$ yarn stryker run --incremental

Expected behavior:
All tests are skipped the second time.

Actual behavior:
Some tests run the second time.

I'm using google translate, so I'm sorry if there are strange parts in the sentences.

Stryker config

{
  "$schema": "./node_modules/@stryker-mutator/core/schema/stryker-schema.json",
  "_comment": "This config was generated using 'stryker init'. Please take a look at: https://stryker-mutator.io/docs/stryker-js/configuration/ for more information.",
  "packageManager": "yarn",
  "reporters": ["html", "clear-text", "progress"],
  "testRunner": "jest",
  "testRunner_comment": "More information about the jest plugin can be found here: https://stryker-mutator.io/docs/stryker-js/jest-runner",
  "coverageAnalysis": "perTest"
}

Stryker environment

+-- @stryker-mutator/core@6.3.0
+-- @stryker-mutator/jest-runner@6.3.0

+-- jest@29.3.1

Test runner environment

$ jest

Your Environment

software	version(s)
node	v18.12.1
npm	9.2.0
Operating System	Ubuntu(WSL2)

Add stryker.log
stryker.log (second run in reproduction steps)

[nicojs]

Hi @mkizka, thanks for opening this issue with detailed reproduction steps!

This is a bug, but not in the line of code you're referring to the problem is here. I forgot to account for more than 1 test starting on the same line when they are the last test in the file 🤦‍♀️.

A current workaround is to add a final test under the tests with the same start position:

const { add } = require("../add");

test.each`
  x    | y    | expected
  ${1} | ${1} | ${2}
  ${1} | ${2} | ${3}
  ${2} | ${2} | ${4}
`("add($x, $y) = $expected", ({ x, y, expected }) => {
  expect(add(x, y)).toBe(expected);
});

+ test('one final test', () => {});

[mkizka]

Thank you for your answer and quick fix!

[nicojs]

Sure thing ☺. I had some time, so you reported it just at the right moment 🤗

I also fixed the bug and released the fix in version 6.3.1