Merge pull request #151 from hmrc/BDOG-2254

BDOG-2254 Preserve case insensitivity of response headers returned fr…

CHANGELOG.md

@@ -1,3 +1,7 @@
+### Version 14.8.0
+
+Fixes case-insensitivity of `HttpResponse#headers` for Scala 2.13
+
 ### Version 14.0.0
 
 Improves hook-data model for auditing.

http-verbs-common/src/main/scala/uk/gov/hmrc/http/CollectionUtils.scala

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 HM Revenue & Customs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package uk.gov.hmrc.http
+
+object CollectionUtils {
+  // play returns scala.collection.Seq, but default for Scala 2.13 is scala.collection.immutable.Seq
+  private [http] def forScala2_13(m: Map[String, scala.collection.Seq[String]]): Map[String, Seq[String]] =
+    // `m.mapValues(_.toSeq).toMap` by itself strips the ordering away
+    scala.collection.immutable.TreeMap[String, Seq[String]]()(scala.math.Ordering.comparatorToOrdering(String.CASE_INSENSITIVE_ORDER)) ++ m.mapValues(_.toSeq)
+
+}

http-verbs-common/src/main/scala/uk/gov/hmrc/http/client/HttpClientV2Impl.scala

@@ -23,7 +23,7 @@ import com.typesafe.config.Config
 import play.api.Configuration
 import play.api.libs.ws.{BodyWritable, EmptyBody, InMemoryBody, SourceBody, WSClient, WSProxyServer, WSRequest, WSResponse}
 import play.core.parsers.FormUrlEncodedParser
-import uk.gov.hmrc.http.{BadGatewayException, BuildInfo, GatewayTimeoutException, HeaderCarrier, HttpReads, HttpResponse, Retries}
+import uk.gov.hmrc.http.{BadGatewayException, BuildInfo, CollectionUtils, GatewayTimeoutException, HeaderCarrier, HttpReads, HttpResponse, Retries}
 import uk.gov.hmrc.play.http.BodyCaptor
 import uk.gov.hmrc.play.http.logging.Mdc
 import uk.gov.hmrc.play.http.ws.WSProxyConfiguration
@@ -240,16 +240,11 @@ class ExecutorImpl(
   )(implicit ec: ExecutionContext
   ): (Future[HttpResponse], Future[ResponseData]) = {
     val auditResponseP = Promise[ResponseData]()
-
-    // play returns scala.collection, but default for Scala 2.13 is scala.collection.immutable
-    def forScala2_13(m: scala.collection.Map[String, scala.collection.Seq[String]]): Map[String, Seq[String]] =
-      m.mapValues(_.toSeq).toMap
-
     val httpResponseF =
       for {
         response <- responseF
         status   =  response.status
-        headers  =  forScala2_13(response.headers)
+        headers  =  CollectionUtils.forScala2_13(response.headers)
       } yield {
         if (isStream) {
           val source =

http-verbs-common/src/main/scala/uk/gov/hmrc/play/http/ws/WSHttpResponse.scala

@@ -23,7 +23,8 @@ import uk.gov.hmrc.http.HttpResponse
 @deprecated("Use WsHttpResponse.apply and HttpResponse instead", "11.0.0")
 class WSHttpResponse(wsResponse: WSResponse) extends HttpResponse {
 
-  override def allHeaders: Map[String, Seq[String]] = wsResponse.headers.mapValues(_.toSeq).toMap
+  override def allHeaders: Map[String, Seq[String]] =
+    WSHttpResponse.forScala2_13(wsResponse.headers)
 
   override def status: Int = wsResponse.status
 
@@ -40,6 +41,12 @@ object WSHttpResponse {
     HttpResponse(
       status  = wsResponse.status,
       body    = wsResponse.body,
-      headers = wsResponse.headers.mapValues(_.toSeq).toMap
+      headers = forScala2_13(wsResponse.headers)
     )
+
+  // play returns scala.collection.Seq, but default for Scala 2.13 is scala.collection.immutable.Seq
+  // duplicated from CollectionUtils since WSHttpResponse is not defined within uk.gov.hmrc.http package..
+  private def forScala2_13(m: Map[String, scala.collection.Seq[String]]): Map[String, Seq[String]] =
+    // `m.mapValues(_.toSeq).toMap` by itself strips the ordering away
+    scala.collection.immutable.TreeMap[String, Seq[String]]()(scala.math.Ordering.comparatorToOrdering(String.CASE_INSENSITIVE_ORDER)) ++ m.mapValues(_.toSeq)
 }

http-verbs-common/src/test/scala/uk/gov/hmrc/http/client/HttpClientV2Spec.scala

@@ -623,6 +623,28 @@ class HttpClientV2Spec
           .withHeader("User-Agent", equalTo("ua2"))
       )
     }
+
+    "return case-insensitive headers" in new Setup {
+      implicit val hc = HeaderCarrier()
+
+      wireMockServer.stubFor(
+        WireMock.get(urlEqualTo("/"))
+          .willReturn(aResponse().withBody("\"res\"").withStatus(200).withHeader("k", "v"))
+      )
+
+      val res: HttpResponse =
+        httpClientV2
+          .get(url"$wireMockUrl/")
+          .withBody(Json.toJson(ReqDomain("req")))
+          .execute[HttpResponse]
+          .futureValue
+
+      res.headers.get("k") shouldBe Some(List("v"))
+      res.headers.get("K") shouldBe Some(List("v"))
+
+      res.header("k") shouldBe Some("v")
+      res.header("K") shouldBe Some("v")
+    }
   }
 
   trait Setup {