From be4f9c37e0fb02fe0f51dd92df2b2c92c33083c5 Mon Sep 17 00:00:00 2001
From: Abdullatif Ghajar <62988232+AbdullatifGhajar@users.noreply.github.com>
Date: Wed, 26 Mar 2025 09:29:48 +0100
Subject: [PATCH] Test and fix #52 (#53)

* Add test to reproduce #52

* Solve issue #52 by improving url handling in SseClientTransport

* Remove unnecessary url processing

---------

Co-authored-by: Abdullatif.Ghajar <abdullatif.ghajar@jetbrains.com>
---
 .../kotlin/sdk/client/SSEClientTransport.kt   |  6 +--
 .../kotlin/integration/SseIntegrationTest.kt  | 51 +++++++++++++++++++
 2 files changed, 54 insertions(+), 3 deletions(-)
 create mode 100644 src/jvmTest/kotlin/integration/SseIntegrationTest.kt

diff --git a/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/SSEClientTransport.kt b/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/SSEClientTransport.kt
index 9e21347..91a9f85 100644
--- a/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/SSEClientTransport.kt
+++ b/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/SSEClientTransport.kt
@@ -39,7 +39,7 @@ public class SseClientTransport(
     private var job: Job? = null
 
     private val baseUrl by lazy {
-        session.call.request.url.toString().removeSuffix("/")
+        session.call.request.url.toString().removeSuffix("/sse")
     }
 
     override suspend fun start() {
@@ -52,7 +52,7 @@ public class SseClientTransport(
 
         session = urlString?.let {
             client.sseSession(
-                urlString = it,
+                urlString = "$it/sse",
                 reconnectionTime = reconnectionTime,
                 block = requestBuilder,
             )
@@ -79,7 +79,7 @@ public class SseClientTransport(
                             val eventData = event.data ?: ""
 
                             // check url correctness
-                            val maybeEndpoint = Url("$baseUrl/$eventData")
+                            val maybeEndpoint = Url(baseUrl + eventData)
 
                             endpoint.complete(maybeEndpoint.toString())
                         } catch (e: Exception) {
diff --git a/src/jvmTest/kotlin/integration/SseIntegrationTest.kt b/src/jvmTest/kotlin/integration/SseIntegrationTest.kt
new file mode 100644
index 0000000..741ea14
--- /dev/null
+++ b/src/jvmTest/kotlin/integration/SseIntegrationTest.kt
@@ -0,0 +1,51 @@
+package integration
+
+import io.ktor.client.*
+import io.ktor.client.plugins.sse.*
+import io.ktor.server.cio.*
+import io.ktor.server.engine.*
+import io.modelcontextprotocol.kotlin.sdk.Implementation
+import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities
+import io.modelcontextprotocol.kotlin.sdk.client.Client
+import io.modelcontextprotocol.kotlin.sdk.client.mcpSse
+import io.modelcontextprotocol.kotlin.sdk.server.Server
+import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions
+import io.modelcontextprotocol.kotlin.sdk.server.mcp
+import kotlinx.coroutines.runBlocking
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertDoesNotThrow
+import io.ktor.client.engine.cio.CIO as ClientCIO
+import io.ktor.server.cio.CIO as ServerCIO
+
+class SseIntegrationTest {
+    @Test
+    fun `client should be able to connect to sse server`() { // runTest will cause network timeout issues
+        runBlocking {
+            val serverEngine = initServer()
+            try {
+                assertDoesNotThrow { initClient() }
+            } finally {
+                // Make sure to stop the server
+                serverEngine.stop(1000, 2000)
+            }
+        }
+    }
+
+    private suspend fun initClient(): Client {
+        return HttpClient(ClientCIO) { install(SSE) }.mcpSse("http://$URL:$PORT")
+    }
+
+    private fun initServer(): EmbeddedServer<CIOApplicationEngine, CIOApplicationEngine.Configuration> {
+        val server = Server(
+            Implementation(name = "sse-e2e-test", version = "1.0.0"),
+            ServerOptions(capabilities = ServerCapabilities()),
+        )
+
+        return embeddedServer(ServerCIO, host = URL, port = PORT) { mcp { server } }.start(wait = false)
+    }
+
+    companion object {
+        private const val PORT = 3001
+        private const val URL = "localhost"
+    }
+}
\ No newline at end of file