KTOR-678 Add test for Auth with Jackson

ktor-server/ktor-server-plugins/ktor-server-auth/build.gradle.kts

@@ -26,5 +26,11 @@ kotlin {
                 api(project(":ktor-server:ktor-server-test-host"))
             }
         }
+        jvmTest {
+            dependencies {
+                api(project(":ktor-server:ktor-server-plugins:ktor-server-content-negotiation"))
+                api(project(":ktor-shared:ktor-serialization:ktor-serialization-jackson"))
+            }
+        }
     }
 }

ktor-server/ktor-server-plugins/ktor-server-auth/jvm/test/io/ktor/tests/auth/AuthWithPlugins.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.tests.auth
+
+import io.ktor.client.request.*
+import io.ktor.http.*
+import io.ktor.serialization.jackson.*
+import io.ktor.server.application.*
+import io.ktor.server.auth.*
+import io.ktor.server.plugins.contentnegotiation.*
+import io.ktor.server.response.*
+import io.ktor.server.routing.*
+import io.ktor.server.testing.*
+import kotlin.test.*
+
+class AuthWithPlugins {
+
+    @Test
+    fun testFormAuthWithJackson() = testApplication {
+        install(ContentNegotiation) {
+            jackson()
+        }
+        install(Authentication) {
+            form {
+                challenge("/unauthorized")
+                validate { credentials ->
+                    if (credentials.name == credentials.password) {
+                        UserIdPrincipal(credentials.name)
+                    } else {
+                        null
+                    }
+                }
+            }
+        }
+
+        routing {
+            get("/unauthorized") {
+                call.respond(HttpStatusCode.Unauthorized, "Unauthorized")
+            }
+            authenticate {
+                post("/test") {
+                    call.respondText("OK")
+                }
+            }
+        }
+
+        val response = client.post("/test") {
+            header(HttpHeaders.ContentType, ContentType.Application.Json)
+            setBody("{}")
+        }
+
+        assertEquals(HttpStatusCode.Found, response.status)
+
+        val location = response.headers[HttpHeaders.Location] ?: fail("Location header is missing")
+        assertEquals("/unauthorized", location)
+    }
+}