Add test with new schema types (#389)

Add tests with new schema types

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->

## How Has This Been Tested?
The repository currently contains duplicated tests:
- tests using the new schema
- tests using the old schema for compatibility checks. they will be
removed once the deprecation level is raised

## Breaking Changes
No

## Types of changes
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [x] Testing

## Checklist
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed

---------

Co-authored-by: Konstantin Pavlov <1517853+kpavlov@users.noreply.github.com>

kotlin-sdk-server/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/server/OldSchemaStdioServerTransportTest.kt

@@ -0,0 +1,140 @@
+package io.modelcontextprotocol.kotlin.sdk.server
+
+import io.modelcontextprotocol.kotlin.sdk.InitializedNotification
+import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
+import io.modelcontextprotocol.kotlin.sdk.PingRequest
+import io.modelcontextprotocol.kotlin.sdk.shared.ReadBuffer
+import io.modelcontextprotocol.kotlin.sdk.shared.serializeMessage
+import io.modelcontextprotocol.kotlin.sdk.toJSON
+import kotlinx.coroutines.CompletableDeferred
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.test.runTest
+import kotlinx.io.Sink
+import kotlinx.io.Source
+import kotlinx.io.asSink
+import kotlinx.io.asSource
+import kotlinx.io.buffered
+import java.io.ByteArrayOutputStream
+import java.io.PipedInputStream
+import java.io.PipedOutputStream
+import kotlin.test.BeforeTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class OldSchemaStdioServerTransportTest {
+    private lateinit var input: PipedInputStream
+    private lateinit var inputWriter: PipedOutputStream
+    private lateinit var outputBuffer: ReadBuffer
+    private lateinit var output: ByteArrayOutputStream
+
+    // We'll store the wrapped streams that meet the constructor requirements
+    private lateinit var bufferedInput: Source
+    private lateinit var printOutput: Sink
+
+    @BeforeTest
+    fun setUp() {
+        // Simulate an input stream that we can push data into using inputWriter.
+        input = PipedInputStream()
+        inputWriter = PipedOutputStream(input)
+
+        outputBuffer = ReadBuffer()
+
+        // A custom ByteArrayOutputStream that appends all written data into outputBuffer
+        output = object : ByteArrayOutputStream() {
+            override fun write(b: ByteArray, off: Int, len: Int) {
+                super.write(b, off, len)
+                outputBuffer.append(b.copyOfRange(off, off + len))
+            }
+        }
+
+        bufferedInput = input.asSource().buffered()
+
+        printOutput = output.asSink().buffered()
+    }
+
+    @Test
+    fun `should start then close cleanly`() {
+        runBlocking {
+            val server = StdioServerTransport(bufferedInput, printOutput)
+            server.onError { error ->
+                throw error
+            }
+
+            var didClose = false
+            server.onClose {
+                didClose = true
+            }
+
+            server.start()
+            assertFalse(didClose, "Should not have closed yet")
+
+            server.close()
+            assertTrue(didClose, "Should have closed after calling close()")
+        }
+    }
+
+    @Test
+    fun `should not read until started`() = runTest {
+        val server = StdioServerTransport(bufferedInput, printOutput)
+        server.onError { error ->
+            throw error
+        }
+
+        var didRead = false
+        val readMessage = CompletableDeferred<JSONRPCMessage>()
+
+        server.onMessage { message ->
+            didRead = true
+            readMessage.complete(message)
+        }
+
+        val message = PingRequest().toJSON()
+
+        // Push a message before the server started
+        val serialized = serializeMessage(message)
+        inputWriter.write(serialized)
+        inputWriter.flush()
+
+        assertFalse(didRead, "Should not have read message before start")
+
+        server.start()
+        val received = readMessage.await()
+        assertEquals(message, received)
+    }
+
+    @Test
+    fun `should read multiple messages`() = runTest {
+        val server = StdioServerTransport(bufferedInput, printOutput)
+        server.onError { error ->
+            throw error
+        }
+
+        val messages = listOf(
+            PingRequest().toJSON(),
+            InitializedNotification().toJSON(),
+        )
+
+        val readMessages = mutableListOf<JSONRPCMessage>()
+        val finished = CompletableDeferred<Unit>()
+
+        server.onMessage { message ->
+            readMessages.add(message)
+            if (message == messages[1]) {
+                finished.complete(Unit)
+            }
+        }
+
+        // Push both messages before starting the server
+        for (m in messages) {
+            inputWriter.write(serializeMessage(m))
+        }
+        inputWriter.flush()
+
+        server.start()
+        finished.await()
+
+        assertEquals(messages, readMessages)
+    }
+}

kotlin-sdk-server/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StdioServerTransportTest.kt

@@ -1,11 +1,11 @@
 package io.modelcontextprotocol.kotlin.sdk.server
 
-import io.modelcontextprotocol.kotlin.sdk.InitializedNotification
-import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
-import io.modelcontextprotocol.kotlin.sdk.PingRequest
 import io.modelcontextprotocol.kotlin.sdk.shared.ReadBuffer
 import io.modelcontextprotocol.kotlin.sdk.shared.serializeMessage
-import io.modelcontextprotocol.kotlin.sdk.toJSON
+import io.modelcontextprotocol.kotlin.sdk.types.InitializedNotification
+import io.modelcontextprotocol.kotlin.sdk.types.JSONRPCMessage
+import io.modelcontextprotocol.kotlin.sdk.types.PingRequest
+import io.modelcontextprotocol.kotlin.sdk.types.toJSON
 import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.test.runTest