Http4s Matchers

Http4sMatchers.scala

import cats.effect.IO
import io.circe.{Decoder, Json}
import org.http4s.circe._
import org.http4s.{Response, Status}
import org.scalatest.EitherValues
import org.scalatest.matchers.{HavePropertyMatchResult, HavePropertyMatcher}

trait Http4sMatchers { this: EitherValues =>
  def status(expected: Status) = HavePropertyMatcher { response: Response[IO] =>
    HavePropertyMatchResult(matches = response.status == expected,
                            propertyName = "status",
                            expectedValue = expected,
                            actualValue = response.status)
  }

  def body[A: Decoder](field: String = ".", expected: A) = HavePropertyMatcher { response: Response[IO] =>
    response
      .as[Json]
      .map(j => if (field == ".") j else j.hcursor.get[A](field).right.value)
      .attempt
      .unsafeRunSync() match {
      case Left(throwable) =>
        HavePropertyMatchResult(
          matches = false,
          propertyName = "body",
          expectedValue = expected.toString(),
          actualValue = s"parsing body as JSON threw exception '${throwable.getMessage}'"
        )
      case Right(actual) =>
        HavePropertyMatchResult(
          matches = actual == expected,
          propertyName = "body",
          expectedValue = expected.toString(),
          actualValue = actual.toString()
        )
    }
  }
}