ST-0024: Per-test-case repetitions

[briancroom]

Hello Swift Community!

The review of ST-0024 “Per-test-case repetitions” begins now and runs through Monday April 20, 2026. The proposal is available here:

swift-evolution/proposals/testing/0024-per-test-case-repetitions.md at main · swiftlang/swift-evolution · GitHub

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Brian Croom
Review Manager

[allevato (Tony Allevato)]

This feels like it's getting into "that proposal review could have been a pull request" territory, because the proposed behavior is obviously how it should work. But I get since it impacts user-facing behavior, yada yada yada...

Ship it.

[grynspan (Jonathan Grynspan)]

We did have that discussion! But yes, it does change how tests run, so the TWG deemed a formal proposal necessary.

Ship it!

[Rod_Brown]

Seems like a bug the previous way it worked. Much improved with the new behaviour. +1

[InstantInteractive (Ricky Sharp)]

Agreed; ship it.

[swhitty (Simon Whitty)]

Excellent!

[briancroom]

Thanks for the feedback so far, folks! As a small update, @harlanhaskins has prepared a branch so I can now share instructions for:

Trying it out!

To try this feature out in a Swift package, add a dependency to the harlan/try-per-test-case-repetitions branch of swift-testing to your package:

...
dependencies: [
  ...
  .package(
    url: "https://github.com/swiftlang/swift-testing.git",
    branch: "harlan/try-per-test-case-repetitions"
  ),
]

Then, add a target dependency to your test target:

.testTarget(
  ...
  dependencies: [
    ...
    .product(name: "Testing", package: "swift-testing"),
  ]
)

Finally, run your tests as usual with swift test:

% swift test
...
◇ Test run started.
↳ Testing Library Version: 6.4-dev (ec33e00)
◇ Test failsAlways() started.
◇ Test succeedsAlways() started.
✔ Test succeedsAlways() passed after 0.001 seconds.
✘ Test failsAlways() recorded an issue at PackageTestExampleTests.swift:5:5: Expectation failed: 1 == 2
↳ 1 == 2 → false
◇ Test failsAlways() started (repetition 2).
✘ Test failsAlways() recorded an issue at PackageTestExampleTests.swift:5:5: Expectation failed: 1 == 2
↳ 1 == 2 → false
◇ Test failsAlways() started (repetition 3).
✘ Test failsAlways() recorded an issue at PackageTestExampleTests.swift:5:5: Expectation failed: 1 == 2
↳ 1 == 2 → false
✘ Test failsAlways() failed after 0.001 seconds with 1 issue.
✘ Test run with 2 tests in 0 suites failed after 0.001 seconds with 1 issue.

[harlanhaskins]

Note that on this branch, all SwiftPM tests are opted in to repetition on failure, with a maximum retry count of 3 (because SwiftPM currently does not pass --repetitions to Swift Testing)

[grynspan (Jonathan Grynspan)]

So, does this proposal include adding those options to SwiftPM or are they a future direction? Because it sounds like to use this feature effectively they need to be formally added, but the text of the proposal is a bit handwavey (he says with great respect, of course!)

[harlanhaskins]

This proposal does not explicitly add the flags to SwiftPM, but we really should add them as a follow up.

EDIT: I posted a PR here to SwiftPM to add these (and will update this proposal to add them). Add `swift test` command line flags for test repetition by harlanhaskins · Pull Request #9944 · swiftlang/swift-package-manager · GitHub

[harlanhaskins]

Hi all, I've posted a PR to update the proposal to add the swift test flags and expose the feature more broadly. Thanks!

[grynspan (Jonathan Grynspan)]

We should make sure the documentation for these flags is clear re: XCTest support. I know Xcode test plans have analogous functionality, but I don't think it's available from the command-line interfaces SwiftPM wraps, and I don't think it's implemented in corelibs-xctest.

[briancroom]

Hi folks, this is now returned for revision to incorporate the SwiftPM flags discussed during the review.