typelevel/cats-effect

Laws testing for queue functor instances

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#1,618 opened on Jan 22, 2021

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 (7 comments) (0 reactions) (0 assignees)Scala (2,230 stars) (572 forks)batch import
good first issue

Description

We have {Functor, Invariant, Contravariant} instances for {Q, Deq, PQ}ueue in cats.effect.std but they currently have no laws tests. We should correct this :)

Contributor guide

Tech stack
scala
Domain
testingbackend
Issue type
test
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Scalacats effectcats laws testing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The issue requests adding laws tests for Functor, Invariant, and Contravariant instances of Q, Deq, and PQ ueue in cats.effect.std. Look at existing law tests for other types (e.g., Ref, Deferred) in the cats effect laws module to understand the pattern. Implement tests using ScalaCheck and Discipline, verifying each typeclass law. Key files to examine include the queue implementations in cats/effect/std and the test suite in cats/effect/tests. Ensure tests are added for all three typeclasses and all three queue types.