feature extractor for Iterator.next

[robstoll]

Code related feature

expect(iterator).next().toEqual(true)

//instead of
expect(iterator).feature { f(it::next) }.toEqual(true)

However, we also want to show a better error message in case there is not a next

Following the things you need to do:

logic

• extend IteratorAssertions with a function next (see ListAssertions.get as a guideline)
• implement next in DefaultIteratorAssertions.kt by using container.extractFeature... (see DefaultListAssertions.get)

api-fluent

• provide a val which returns Expect<T> in iteratorFeatureExtractors.kt (see listFeatureExtractors.kt as a guideline)
• provide a fun which expects an assertionCreator-lambda and returns Expect<E> (where E is the element type in Iterator<E>) in iteratorFeatureExtractors.kt (see listFeatureExtractors.kt as a guideline)
• extend or write a separate Spec named IteratorFeatureExtractorSpec in specs -> commonMain (see for instance ListExpectationsSpec) and extend it in atrium-api-fluent -> commonTest
• add samples to IteratorFeatureExtractorSamples.kt (see ListFeatureExtractorSamples.kt as guideline -- try to provide the reason why an expectation fails)
• add @sample with link to your sample method to the two functions in iteratorExpectations.kt
• add @since 1.3.0 (adapt to current milestone) to KDOC of the two functions in iteratorExpectations.kt

api-infix

• provide a val which returns Expect<T> in iteratorExpectations.kt (see listExpectations.kt as a guideline)
• provide a fun which expects an assertionCreator-lambda and returns Expect<E> (where E is the element type in Iterator<E>) in iteratorFeatureExtractors.kt (see listFeatureExtractors.kt as a guideline)
• extend or write a separate Spec named IteratorFeatureExtractorSpec in specs -> commonMain (see for instance ListExpectationsSpec) and extend it in atrium-api-infix -> commonTest
• add samples to IteratorFeatureExtractorSamples.kt (see ListFeatureExtractorSamples.kt as guideline -- try to provide the reason why an expectation fails)
• add @sample with link to your sample method to the two functions in iteratorExpectations.kt
• add @since 1.3.0 (adapt to current milestone) to KDOC of the two functions in iteratorExpectations.kt

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[hubtanaka]

I'll work on this

[hubtanaka]

My weekend is almost over, but still work in progress.
Therefore, I would like to write a short interim report once.

I'm currently struggling with IteratorExpectationsSpec.kt.
I thought that next function throw an AssertionError when it is invoked by the iterator of the empty list.
However, toThrow , in expect { /* empty list iterator invoke next */ }.toThrow<AssertionError>{ .. } , throws AtriumError.
I've read ListExpectationsSpec.kt and the getFunction related code, but I still can't find what to do.

So it seems better to write samples first.
Then return to the TODO for IteratorExpectationsSpec.kt.

[robstoll]

AtriumError is an AssertionError, we don't mention it in the API as it is an implementation detail. We might as well change to another AssertionError in the future.

[hubtanaka]

Thanks for your comment.

AtriumError is an AssertionError

I see. Then I might have been missing something else.

By the way, today I wrote samples for Iterable.next (api-fluent).
As a result, the tests passed.
Therefore, my next function implementation seems not so bad at least.

So, I think I am just misunderstanding something about IteratorExpectationsSpec.
I'll read some related code tomorrow and try to find it out.

[hubtanaka]

I finally realized what I have missed.

In toThrow<AssertionError>{ .. }, I have passed TO_HAVE into messageToContain.
I fixed it to SIZE_EXCEEDED, then Test passed.

AtriumError is an AssertionError

Thanks to this comment I realized my mistake.