Sometimes it might be helpful to have an assertion helper in integration tests to assert that specific extension keys are present in the produced outEvent, not knowing the extension values upfront, such as when the transport adds extensions. The current helpers always compare extension keys and values which fails the test.

Proposing test.HasExtensionsKeys to only assert that a specific extension key is set if the value is not known upfront/not of interest during assertions.

Ref: https://github.com/cloudevents/sdk-go/pull/896/files#r1203500742