The first Kotest release of 2026 is here - 6.1 'Bouncing Boimler'

• Compatible with Kotlin 2.0, 2.1, 2.2 and 2.3
• Enhanced data-testing with new syntax that mirrors the spec style to enable more intuitive tests. This also gives you control over how data tests interact with test lifecycle callbacks!
• Much improved IDE plugin support including running individual tests for native targets and fixes for many long standing issues. Re-run tests and jump to source for all nested tests in JVM mode
• The test framework has been updated with Jasmine style f-focused syntax to mirror the x-disabled syntax.
• Support for JUnit 6 via the new kotest-runner-junit6 module.
• The popular TestContainers extension has been updated to support Docker ComposeContainers. Also now with an option to pipe the container logs directly into the test output for easier debugging!
• Full support for the Gradle test-retry plugin.
• Many improvements and bug fixes to our assertions library including support for custom equality in shouldBe assertions
• New assertions added such as shouldBeAtMost(x) and shouldBeAtLeast(y) for primitives. A reminder that assertions don't require the Kotest test framework. They are still the best Kotlin assertions library, in our opinion, even if you are using JUnit or another test framework.
• Recreate race conditions easily using our parallel runner.
• Various property test improvements such as new Arb types for arrays and support for specifying Arb collection sizes globally. Just like assertions, the property testing library doesn't require the Kotest test framework.

What's Changed

• Removing deprecated EqualityMatcherResult by @sksamuel in https://github.com/kotest/kotest/pull/5239
• Migrate to Test Containers version 2 by @sksamuel in https://github.com/kotest/kotest/pull/5240
• Add specific JUnit 6 runner by @sksamuel in https://github.com/kotest/kotest/pull/5230
• Makes beBoolean matcher public by @LeoColman in https://github.com/kotest/kotest/pull/5241
• update kdoc for ComposeContainerProjectExtension by @alfonsoristorato in https://github.com/kotest/kotest/pull/5247
• Fix compatibility note for shouldThrowSoftly by @AlexCue987 in https://github.com/kotest/kotest/pull/5250
• support-nullable-primitive-arrays in Arb by @AlexCue987 in https://github.com/kotest/kotest/pull/5249
• Clarify assertions in core.md documentation by @AlexCue987 in https://github.com/kotest/kotest/pull/5253
• Add additional blog links to documentation by @AlexCue987 in https://github.com/kotest/kotest/pull/5254
• docs: fix typo in property test shrinking documentation by @jongheon1 in https://github.com/kotest/kotest/pull/5256
• Bump kotlin-compile-testing to version 0.11.0 in libs.versions.toml. by @sksamuel in https://github.com/kotest/kotest/pull/5251
• Added backwards compatible methods for nondeterministic testing by @sksamuel in https://github.com/kotest/kotest/pull/5258
• Fix config being loaded twice by @sksamuel in https://github.com/kotest/kotest/pull/5259
• Add shouldContainAllInAnyOrder matchers for collections by @sksamuel in https://github.com/kotest/kotest/pull/5228
• make containAllInAnyOrder ignore elements not in expected (#5264) by @AlexCue987 in https://github.com/kotest/kotest/pull/5265
• Update project_config.md to mention file name by @nkiesel in https://github.com/kotest/kotest/pull/5272
• make-containAllInAnyOrder-for-sequences-do-same-thing-as-collections … by @AlexCue987 in https://github.com/kotest/kotest/pull/5269
• handle duplicate test names in InstancePerLeaf and InstancePerTest (issue #5261) by @alfonsoristorato in https://github.com/kotest/kotest/pull/5274
• Added a special --tests filter for the intellij plugin by @sksamuel in https://github.com/kotest/kotest/pull/5165
• Fix typo in eventually.md: determistic => deterministic by @AlexCue987 in https://github.com/kotest/kotest/pull/5278
• continually-timeout-is-success take2 by @AlexCue987 in https://github.com/kotest/kotest/pull/5276
• Clarify default poll interval in continually documentation by @AlexCue987 in https://github.com/kotest/kotest/pull/5277
• Enhance continually.md with listener example by @AlexCue987 in https://github.com/kotest/kotest/pull/5282

New Contributors

• @jongheon1 made their first contribution in https://github.com/kotest/kotest/pull/5256
• @nkiesel made their first contribution in https://github.com/kotest/kotest/pull/5272
• @kamilszymanski made their first contribution in https://github.com/kotest/kotest/pull/5311
• @alex28sh made their first contribution in https://github.com/kotest/kotest/pull/5561
• @jay05410 made their first contribution in https://github.com/kotest/kotest/pull/5567

Full Changelog: https://github.com/kotest/kotest/compare/v6.0.7...v6.1.0