chore: avoid multiple calls to onclose when terminating

Author: johnnyasantoss

src/client/stdio.ts

@@ -138,7 +138,6 @@ export class StdioClientTransport implements Transport {
       this._process.on("error", (error) => {
         if (error.name === "AbortError") {
           // Expected when close() is called.
-          this.onclose?.();
           return;
         }
 

src/integration-tests/process-cleanup.test.ts

@@ -60,4 +60,30 @@ describe("Process cleanup", () => {
 
     expect(isProcessRunning(pid!)).toBe(false);
   });
+
+  it("onclose should be called exactly once", async () => {
+    const client = new Client({
+      name: "test-client",
+      version: "1.0.0",
+    });
+
+    const transport = new StdioClientTransport({
+      command: process.argv0,
+      args: ["test-server.js"],
+      cwd: __dirname,
+    });
+
+    let onCloseWasCalled = 0;
+    client.onclose = () => {
+      onCloseWasCalled++;
+    };
+
+    await client.connect(transport);
+    await client.close();
+
+    // A short delay to allow the close event to propagate
+    await new Promise((resolve) => setTimeout(resolve, 50));
+
+    expect(onCloseWasCalled).toBe(1);
+  });
 });

src/integration-tests/test-server.js

@@ -0,0 +1,11 @@
+import { McpServer } from "../../dist/esm/server/mcp.js";
+import { StdioServerTransport } from "../../dist/esm/server/stdio.js";
+
+const transport = new StdioServerTransport();
+
+const server = new McpServer({
+  name: "test-server",
+  version: "1.0.0",
+});
+
+await server.connect(transport);