Add circe support module

2 files changed, 145 insertions, 0 deletions

diff --git a/circe/src/main/scala/com/softwaremill/sttp/circe/circe.scala b/circe/src/main/scala/com/softwaremill/sttp/circe/circe.scala
new file mode 100644
index 0000000..0233f08
--- /dev/null
+++ b/circe/src/main/scala/com/softwaremill/sttp/circe/circe.scala
@@ -0,0 +1,32 @@
+package com.softwaremill.sttp
+
+import com.softwaremill.sttp.model.{
+  RequestBody,
+  ResponseAs,
+  SerializableBody,
+  StringBody
+}
+import io.circe.parser._
+import io.circe.{Decoder, Encoder}
+
+import scala.language.higherKinds
+
+package object circe {
+  private[sttp] val ApplicationJsonContentType = "application/json"
+
+  private def serializeBody[B](body: B)(
+      implicit encoder: Encoder[B]): RequestBody[Nothing] =
+    SerializableBody((b: B) => StringBody(encoder(b).noSpaces, Utf8), body)
+
+  implicit final class CirceRequestTOps[U[_], T, +S](val req: RequestT[U, T, S])
+      extends AnyVal {
+    def jsonBody[B: Encoder](body: B): RequestT[U, T, S] =
+      req
+        .setContentTypeIfMissing(ApplicationJsonContentType)
+        .copy(body = serializeBody(body))
+  }
+
+  def asJson[B: Decoder]: ResponseAs[Either[io.circe.Error, B], Nothing] =
+    asString(Utf8).map(decode[B])
+
+}
diff --git a/circe/src/test/scala/com/softwaremill/sttp/CirceTests.scala b/circe/src/test/scala/com/softwaremill/sttp/CirceTests.scala
new file mode 100644
index 0000000..abd20ef
--- /dev/null
+++ b/circe/src/test/scala/com/softwaremill/sttp/CirceTests.scala
@@ -0,0 +1,113 @@
+package com.softwaremill.sttp
+
+import com.softwaremill.sttp.model._
+import io.circe._
+import org.scalatest._
+
+import scala.language.higherKinds
+
+class CirceTests extends FlatSpec with Matchers with EitherValues {
+  import circe._
+
+  "The circe module" should "encode arbitrary bodies given an encoder" in {
+    val body = Outer(Inner(42, true, "horses"), "cats")
+    val expected = """{"foo":{"a":42,"b":true,"c":"horses"},"bar":"cats"}"""
+
+    val req = sttp.jsonBody(body)
+
+    extractBody(req) shouldBe expected
+  }
+
+  it should "decode arbitrary bodies given a decoder" in {
+    val body = """{"foo":{"a":42,"b":true,"c":"horses"},"bar":"cats"}"""
+    val expected = Outer(Inner(42, true, "horses"), "cats")
+
+    val responseAs = asJson[Outer]
+
+    runJsonResponseAs(responseAs)(body).right.value shouldBe expected
+  }
+
+  it should "fail to decode invalid json" in {
+    val body = """not valid json"""
+
+    val responseAs = asJson[Outer]
+
+    runJsonResponseAs(responseAs)(body).left.value shouldBe an[io.circe.Error]
+  }
+
+  it should "should encode and decode back to the same thing" in {
+    val outer = Outer(Inner(42, true, "horses"), "cats")
+
+    val encoded = extractBody(sttp.jsonBody(outer))
+    val decoded = runJsonResponseAs(asJson[Outer])(encoded)
+
+    decoded.right.value shouldBe outer
+  }
+
+  it should "set the content type" in {
+    val body = Outer(Inner(42, true, "horses"), "cats")
+    val req = sttp.jsonBody(body)
+
+    val ct = req.headers.toMap.get("Content-Type")
+
+    ct shouldBe Some("application/json")
+  }
+
+  it should "only set the content type if it was not set earlier" in {
+    val body = Outer(Inner(42, true, "horses"), "cats")
+    val req = sttp.contentType("horses/cats").jsonBody(body)
+
+    val ct = req.headers.toMap.get("Content-Type")
+
+    ct shouldBe Some("horses/cats")
+  }
+
+  case class Inner(a: Int, b: Boolean, c: String)
+
+  object Inner {
+    implicit val encoder: Encoder[Inner] =
+      Encoder.forProduct3("a", "b", "c")(i => (i.a, i.b, i.c))
+    implicit val decoder: Decoder[Inner] =
+      Decoder.forProduct3("a", "b", "c")(Inner.apply)
+  }
+
+  case class Outer(foo: Inner, bar: String)
+
+  object Outer {
+    implicit val encoder: Encoder[Outer] =
+      Encoder.forProduct2("foo", "bar")(o => (o.foo, o.bar))
+    implicit val decoder: Decoder[Outer] =
+      Decoder.forProduct2("foo", "bar")(Outer.apply)
+  }
+
+  def extractBody[A[_], B, C](request: RequestT[A, B, C]): String =
+    request.body match {
+      case SerializableBody(serializer, body) =>
+        serializer(body) match {
+          case StringBody(body, "utf-8") =>
+            body
+          case StringBody(_, encoding) =>
+            fail(
+              s"Request body serializes to StringBody with wrong encoding: $encoding")
+          case _ =>
+            fail("Request body does not serialize to StringBody")
+        }
+      case _ =>
+        fail("Request body is not SerializableBody")
+    }
+
+  def runJsonResponseAs[A](responseAs: ResponseAs[A, Nothing]): String => A =
+    responseAs match {
+      case responseAs: MappedResponseAs[_, A, Nothing] =>
+        responseAs.raw match {
+          case ResponseAsString("utf-8") =>
+            responseAs.g
+          case ResponseAsString(encoding) =>
+            fail(
+              s"MappedResponseAs wraps a ResponseAsString with wrong encoding: $encoding")
+          case _ =>
+            fail("MappedResponseAs does not wrap a ResponseAsString")
+        }
+      case _ => fail("ResponseAs is not a MappedResponseAs")
+    }
+}