When http4s met MUnit

Integration library between MUnit and http4s.

• Installation
• Contributors to this project
• Usage
  • Testing HttpRoutes
  • Testing AuthedRoutes
  • Using a mocked http4s Client
  • Testing a remote HTTP server
  • Testing an HTTP server running inside a container
• Other features
  • Tagging your tests
  • Stress-testing
  • Nested requests
  • Test names
  • Body in failed assertions
  • Response clues

Installation

Add the following line to your build.sbt file:

libraryDependencies += "com.alejandrohdezma" %% "http4s-munit" % "0.15.1" % Test

Contributors to this project

alejandrohdezma	gutiory	JackTreble

Usage

Testing HttpRoutes

We can use the Http4sHttpRoutesSuite to write tests for an HttpRoutes using Request[IO] values easily:

import cats.effect.IO

import org.http4s._

class MyHttpRoutesSuite extends munit.Http4sHttpRoutesSuite {

  override val routes: HttpRoutes[IO] = HttpRoutes.of {
    case GET -> Root / "hello"        => Ok("Hi")
    case GET -> Root / "hello" / name => Ok(s"Hi $name")
  }

  test(GET(uri"hello" / "Jose")).alias("Say hello to Jose") { response =>
    assertIO(response.as[String], "Hi Jose")
  }

  // You can also override routes per-test
  test(GET(uri"hello" / "Jose"))
    .withRoutes(HttpRoutes.of[IO] { case GET -> Root / "hello" / _=> Ok("Hi") })
    .alias("Overriden routes") { response =>
      assertIO(response.as[String], "Hi")
    }

}

The test method receives a Request[IO] object and when the test runs, it runs that request against the provided routes and let you assert the response.

http4s-munit will automatically name your tests using the information of the provided Request. For example, for the test shown in the previous code snippet, the following will be shown when running the test:

munit.MyHttpRoutesSuite:0s
  + GET -> hello/Jose (Say hello to Jose) 0.014s

Testing AuthedRoutes

If we want to test authenticated routes (AuthedRoutes in http4s) we can use the Http4sAuthedRoutesSuite. It is completely similar to the previous suite, except that we need to ensure a Show instance is available for the auth "context" type and that we need to provide AuthedRequest instead of Request in the test definition. We can do this using its own constructor or by using our extension function context or ->:

import cats.effect.IO

import org.http4s._

class MyAuthedRoutesSuite extends munit.Http4sAuthedRoutesSuite[String] {

  override val routes: AuthedRoutes[String, IO] = AuthedRoutes.of {
    case GET -> Root / "hello" as user        => Ok(s"$user: Hi")
    case GET -> Root / "hello" / name as user => Ok(s"$user: Hi $name")
  }

  test(GET(uri"hello" / "Jose").context("alex")).alias("Say hello to Jose") { response =>
    assertIO(response.as[String], "alex: Hi Jose")
  }

  // You can also override routes per-test
  test(GET(uri"hello" / "Jose") -> "alex")
    .withRoutes(AuthedRoutes.of[String, IO] { case GET -> Root / "hello" / _ as _ => Ok("Hey") })
    .alias("Overriden routes") { response =>
      assertIO(response.as[String], "Hey")
    }

}

Using a mocked http4s Client

If you want to add tests for a class or algebra that uses a Client instance you can make your suite extend ClientSuite.

It adds two extension methods to the Client companion object: from and fixture.

Client.from lets you create a mocked client from a partial function representing routes:

import org.http4s.client.Client

class ClientSuiteSuite extends munit.ClientSuite {

  val client = Client.from {
    case GET -> Root / "ping" => Ok("pong")
  }

}

On the other hand, the class also provides another extension method: Client.fixture. This method is inteded to be used to easily create a fixture for testing a class that uses an http4s' Client.

Given an algebra like:

import cats.effect._
import org.http4s.client.Client

trait PingService[F[_]] {

  def ping(): F[String]

}

object PingService {

  def create[F[_]: Async](client: Client[F]) =
    new PingService[F] {

      def ping(): F[String] = client.expect[String]("ping")

    }
  

}

You can test it using ClientSuite like:

import cats.effect._
import org.http4s.client.Client

class PingServiceSuite extends munit.ClientSuite {

  val fixture = Client.fixture(client => Resource.pure(PingService.create(client)))

  fixture {
    case GET -> Root / "ping" => Ok("pong")
  }.test("PingService.ping works") { service =>
    val result = service.ping()

    assertIO(result, "pong")
  }

}

Testing a remote HTTP server

In the case you don't want to use static http4s routes, but a running HTTP server, you have available the HttpSuite. This suite behaves exactly the same as the previous ones except that you don't provide a routes object, but a baseUri with the URI of your HTTP server. Any Request added in tests will prepend this URI before making a call using a real http4s Client. By default the library uses Ember as the client implementation (although you'll need to provide its dependency explicitly). If you want to use a different implementation just override http4sMUnitClient.

import cats.effect.IO
import cats.effect.Resource

import io.circe.Json

import org.http4s._
import org.http4s.circe._
import org.http4s.client.Client
import org.http4s.blaze.client.BlazeClientBuilder

class GitHubSuite extends munit.HttpSuite {

  override def http4sMUnitClient: Resource[IO, Client[IO]] = BlazeClientBuilder[IO].resource

  override val baseUri: Uri = uri"https://api.github.com"

  test(GET(uri"users/gutiory")) { response =>
    assertEquals(response.status.code, 200)

    val result = response.as[Json].map(_.hcursor.get[String]("login"))

    assertIO(result, Right("gutiory"))
  }

}

Testing an HTTP server running inside a container

Testing a Docker container with TestContainers and http4s-munit is easy. You just need to use TestCotnainersFixtures and use an HttpSuite to connect to it:

import cats.effect.IO

import com.dimafeng.testcontainers.GenericContainer
import com.dimafeng.testcontainers.munit.fixtures.TestContainersFixtures
import io.circe.Json
import org.http4s._
import org.http4s.circe._
import org.http4s.ember.client.EmberClientBuilder

class TestContainersSuite extends munit.HttpSuite with TestContainersFixtures {

  override def http4sMUnitClient = EmberClientBuilder.default[IO].build

  // There is also available `ForEachContainerFixture`
  val container = ForAllContainerFixture {
    GenericContainer(dockerImage = "mendhak/http-https-echo", exposedPorts = List(80))
  }

  override def munitFixtures = List(container)

  override def baseUri() = Uri.unsafeFromString(s"http://localhost:${container().mappedPort(80)}")

  test(GET(uri"ping")) { response =>
    assertEquals(response.status.code, 200)
    assertIOBoolean(response.as[Json].map(_.isObject))
  }

}

Or if you don't want to use container fixtures and you don't mind starting a container for each test:

import cats.effect.IO
import cats.effect.Resource
import cats.syntax.all._

import com.dimafeng.testcontainers.GenericContainer
import io.circe.Json
import org.http4s.circe._
import org.http4s.ember.client.EmberClientBuilder

class TestContainersSuite extends munit.HttpSuite {

  override def http4sMUnitClient =
    Resource.fromAutoCloseable(IO(container.start()).as(container)) >> EmberClientBuilder.default[IO].build

  lazy val container = GenericContainer(dockerImage = "mendhak/http-https-echo", exposedPorts = List(80))

  override def baseUri() = localhost.withPort(container.mappedPort(80))

  test(GET(uri"ping")) { response =>
    assertEquals(response.status.code, 200)
    assertIOBoolean(response.as[Json].map(_.isObject))
  }

}

Other features

Tagging your tests

Once the request has been passed to the test method, we can tag our tests before implementing them:

// Marks the test as failing (it will pass if the assertion fails)
test(GET(uri"hello")).fail { response => assertEquals(response.status.code, 200) }

// Marks a test as "flaky". Check MUnit docs to know more about this feature:
// https://scalameta.org/munit/docs/tests.html#tag-flaky-tests
test(GET(uri"hello")).flaky { response => assertEquals(response.status.code, 200) }

// Skips this test when running the suite
test(GET(uri"hello")).ignore { response => assertEquals(response.status.code, 200) }

// Runs only this test when running the suite
test(GET(uri"hello")).only { response => assertEquals(response.status.code, 200) }

// We can also use our own tags, just like with MUnit `test`
val IntegrationTest = new munit.Tag("integration-test")
test(GET(uri"hello")).tag(IntegrationTest) { response => assertEquals(response.status.code, 200) }

Stress-testing

http4s-munit includes a small feature that allows you to "stress-test" a service. Once the request has been passed to the test method, we can call several methods to enable test repetition and parallelization:

test(GET(uri"hello"))
  .repeat(50)
  .parallel(10) { response => 
    assertEquals(response.status.code, 200) 
  }

On the other hand, if you do not want to have to call these methods for each test, you also have the possibility to enable repetition and parallelization using system properties or environment variables:

• Using environment variables:

  export HTTP4S_MUNIT_REPETITIONS=50
  export HTTP4S_MUNIT_MAX_PARALLEL=10
  
  sbt test
  

• Using system properties:

  sbt -Dhttp4s.munit.repetitions=50 -Dhttp4s.munit.max.parallel=10 test
  

Also, when multiple errors occured while running repeated tests, you can control wheter http4s-munit should output all failures or not using:

# Using environment variable
export HTTP4S_SHOW_ALL_STACK_TRACES=true

# Using system property
sbt -Dhttp4s.munit.showAllStackTraces=true test

Finally, if you want to disable repetitions for a specific test when using environment variables or system properties, you can use doNotRepeat:

test(GET(uri"hello")).doNotRepeat { response => 
  assertEquals(response.status.code, 200) 
}

Nested requests

Sometimes (mostly while using the HttpSuite or HttpFromContainerSuite) one test needs some pre-condition in order to be executed (e.g., in order to test the deletion of a user, you need to create it first). In such cases, once the request has been passed to the test method, we can call andThen to provide nested requests from the response of the previous one:

test(GET(uri"posts" +? ("number" -> 10)))
    .alias("look for the 10th post")
    .andThen("delete it")(_.as[String].map { id =>
      DELETE(uri"posts" / id)
    }) { response =>
      assertEquals(response.status.code, 204)
    }

Test names

The generated test names can be customized by overriding http4sMUnitNameCreator. Allows altering the name of the generated tests.

By default this method generate test names like:

// GET -> users/42
test(GET(uri"users" / "42"))

// GET -> users (all users)
test(GET(uri"users")).alias("all users")

// GET -> users - executed 10 times with 2 in parallel
test(GET(uri"users")).repeat(10).parallel(2)

// GET -> posts?number=10 (look for the 10th post and delete it)
test(GET(uri"posts" +? ("number" -> 10)))
    .alias("look for the 10th post")
    .andThen("delete it")(_.as[String].map { id => DELETE(uri"posts" / id) })

Body in failed assertions

http4s-munit always includes the responses body in a failed assertion's message.

For example, when running the following suite...

import cats.effect.IO

import org.http4s._

class MySuite extends munit.Http4sHttpRoutesSuite {

  val routes: HttpRoutes[IO] = HttpRoutes.pure(Response().withEntity("""{"id": 1, "name": "Jose"}"""))

  test(GET(uri"users"))(response => assertEquals(response.status.code, 204))

}

...it will fail with this message:

X MySuite.GET -> users  0.042s munit.ComparisonFailException: MySuite.scala:12
12:  test(GET(uri"users"))(response => assertEquals(response.status.code, 204))
values are not the same
=> Obtained
200
=> Diff (- obtained, + expected)
-200
+204

Response body was:

{
  "id": 1,
  "name": "Jose"
}

The body will be prettified using http4sMUnitBodyPrettifier, which, by default, will try to parse it as JSON and apply a code highlight if munitAnsiColors is true. If you want a different output or disabling body-prettifying just override this method.

Response clues

Apart from the response body clues introduced in the previous section, http4s-munit also provides a simple way to transform a response into clues: the response.clues extension method.

The output of this extension method can be tweaked by using the http4sMUnitResponseClueCreator.

For example, this can be used on container suites to filter logs relevant to the current request (if your logs are JSON objects containing the request id):

import cats.effect.IO
import cats.effect.Resource
import cats.syntax.all._

import com.dimafeng.testcontainers.GenericContainer
import io.circe.Json
import org.http4s._
import org.http4s.circe._
import org.http4s.ember.client.EmberClientBuilder
import org.typelevel.ci._

class TestContainersSuite extends munit.HttpSuite {

  override def http4sMUnitClient =
    Resource.fromAutoCloseable(IO(container.start()).as(container)) >> EmberClientBuilder.default[IO].build

  override def http4sMUnitResponseClueCreator(response: Response[IO]) = {
    val logs = response.headers
      .get(ci"x-request-id")
      .map(_.head.value)
      .map(id => container.logs.split("\n").filter(_.contains(id)).mkString("\n"))
      .getOrElse(container.logs)

    clues(response, logs)
  }

  lazy val container = GenericContainer(dockerImage = "mendhak/http-https-echo", exposedPorts = List(80))

  override def baseUri() = Uri.unsafeFromString(s"http://localhost:${container.mappedPort(80)}")

  test(GET(uri"ping")) { response =>
    assertEquals(response.status.code, 200, response.clues)
    assertIOBoolean(response.as[Json].map(_.isObject), response.clues)
  }

}