Platform (all, jvm, js): jvm
Extension (none, kotlin 1.3): none

Code related feature
expect(path).notToBeExecutable()

//instead of

expect(path).feature { f(it::isExecutable) }.toEqual(false)
Following the things you need to do:

logic

extend PathAssertions with a function isNotExecutable (see PathAssertions as a guideline)
implement isNotReadable in DefaultPathAssertions.kt by using the ExpectImpl.feature.extractor...
run ./gradlew generateLogic which will update path.kt in logic
api-fluent

provide a function notToBeExecutable which returns Expect in pathExpectations.kt (see pathExpectations.kt toBeExecutable as a guideline)
add @SInCE 0.17.0 (adapt to current milestone) to KDOC
extend or write a separate Spec named PathExpectationsSpec in specs-common (see for instance PathExpectationsSpec) and extend it in atrium-api-fluent-en_GB-common/src/test
api-infix

provide a function notToBeExecutable which returns Expect in pathExpectations.kt (see pathExpectations.kt toBeExecutable as a guideline)
add @SInCE 0.17.0 (adapt to current milestone) to KDOC
extend or write a separate Spec named PathExpectationsSpec in specs-common (see for instance PathExpectationsSpec) and extend it in atrium-api-infix-en_GB-common/src/test
Your first contribution?
Write a comment I'll work on this if you would like to take this issue over.
This way we get the chance to revise the description in case things have changed in the meantime, we might give you additional hints and we can assign the task to you, so that others do not start as well.
See Your first code contribution for guidelines.
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