Enhance StdioClientTransportTest with clean shutdown validation, error handling, and added assertions. Extend timeout for stability.

Author: kpavlov

kotlin-sdk-test/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/client/StdioClientTransportTest.kt

@@ -3,6 +3,7 @@ package io.modelcontextprotocol.kotlin.sdk.client
 import io.modelcontextprotocol.kotlin.sdk.shared.BaseTransportTest
 import io.modelcontextprotocol.kotlin.sdk.types.Implementation
 import io.modelcontextprotocol.kotlin.sdk.types.McpException
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.test.runTest
 import kotlinx.io.asSink
@@ -12,12 +13,18 @@ import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.Timeout
 import org.junit.jupiter.api.assertThrows
 import java.util.concurrent.TimeUnit
-
-@Timeout(20, unit = TimeUnit.SECONDS)
+import kotlin.concurrent.atomics.AtomicBoolean
+import kotlin.concurrent.atomics.ExperimentalAtomicApi
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+import kotlin.test.fail
+import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.seconds
+
+@Timeout(30, unit = TimeUnit.SECONDS)
 class StdioClientTransportTest : BaseTransportTest() {
 
     @Test
-    @Timeout(30, unit = TimeUnit.SECONDS)
     fun `handle stdio error`(): Unit = runBlocking {
         val processBuilder = if (System.getProperty("os.name").lowercase().contains("win")) {
             ProcessBuilder("cmd", "/c", "pause 1 && echo simulated error 1>&2 && exit 1")
@@ -55,6 +62,7 @@ class StdioClientTransportTest : BaseTransportTest() {
         process.destroyForcibly()
     }
 
+    @OptIn(ExperimentalAtomicApi::class)
     @Test
     fun `should start then close cleanly`() = runTest {
         // Run process "/usr/bin/tee"
@@ -63,15 +71,33 @@ class StdioClientTransportTest : BaseTransportTest() {
 
         val input = process.inputStream.asSource().buffered()
         val output = process.outputStream.asSink().buffered()
+        val error = process.errorStream.asSource().buffered()
 
         val transport = StdioClientTransport(
             input = input,
             output = output,
+            error = error,
         )
 
-        testTransportOpenClose(transport)
+        transport.onError { error ->
+            fail("Unexpected error: $error")
+        }
+
+        val didClose = AtomicBoolean(false)
+        transport.onClose { didClose.store(true) }
+
+        transport.start()
+        delay(1.seconds)
 
+        assertFalse(didClose.load(), "Transport should not be closed immediately after start")
+
+        // Destroy process BEFORE close() to unblock stdin reader
         process.destroyForcibly()
+        delay(100.milliseconds) // Give time for EOF to propagate
+
+        transport.close()
+
+        assertTrue(didClose.load(), "Transport should be closed after close() call")
     }
 
     @Test