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feat(client): add reconnectionScheduler to StreamableHTTPClientTransport (#1763)

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Co-authored-by: CHOIJEWON <alsrn6040@kakao.com>
This commit is contained in:
Felix Weinberger 2026-03-30 14:02:20 +01:00 • committed by GitHub
commit 6711ed9ae8
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1 changed files with 241 additions and 19 deletions
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148
packages/client/test/client/streamableHttp.test.ts
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@ -4,7 +4,7 @@ import type { Mock, Mocked } from 'vitest';
import type { OAuthClientProvider } from '../../src/client/auth.js';
import { UnauthorizedError } from '../../src/client/auth.js';
import type { StartSSEOptions, StreamableHTTPReconnectionOptions } from '../../src/client/streamableHttp.js';
import type { ReconnectionScheduler, StartSSEOptions, StreamableHTTPReconnectionOptions } from '../../src/client/streamableHttp.js';
import { StreamableHTTPClientTransport } from '../../src/client/streamableHttp.js';
describe('StreamableHTTPClientTransport', () => {
@ -1617,8 +1617,8 @@ describe('StreamableHTTPClientTransport', () => {
})
);
// Verify no timeout was scheduled (no reconnection attempt)
expect(transport['_reconnectionTimeout']).toBeUndefined();
// Verify no reconnection was scheduled
expect(transport['_cancelReconnection']).toBeUndefined();
});
it('should schedule reconnection when maxRetries is greater than 0', async () => {
@ -1640,10 +1640,10 @@ describe('StreamableHTTPClientTransport', () => {
// ASSERT - should schedule a reconnection, not report error yet
expect(errorSpy).not.toHaveBeenCalled();
expect(transport['_reconnectionTimeout']).toBeDefined();
expect(transport['_cancelReconnection']).toBeDefined();
// Clean up the timeout to avoid test pollution
clearTimeout(transport['_reconnectionTimeout']);
// Clean up the pending reconnection to avoid test pollution
transport['_cancelReconnection']?.();
});
});
@ -1716,4 +1716,140 @@ describe('StreamableHTTPClientTransport', () => {
});
});
});
describe('reconnectionScheduler', () => {
const reconnectionOptions: StreamableHTTPReconnectionOptions = {
initialReconnectionDelay: 1000,
maxReconnectionDelay: 5000,
reconnectionDelayGrowFactor: 2,
maxRetries: 3
};
function triggerReconnection(t: StreamableHTTPClientTransport): void {
(t as unknown as { _scheduleReconnection(opts: StartSSEOptions, attempt?: number): void })._scheduleReconnection({}, 0);
}
beforeEach(() => {
vi.useFakeTimers();
});
afterEach(() => {
vi.useRealTimers();
});
it('invokes the custom scheduler with reconnect, delay, and attemptCount', () => {
const scheduler = vi.fn<ReconnectionScheduler>();
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions,
reconnectionScheduler: scheduler
});
triggerReconnection(transport);
expect(scheduler).toHaveBeenCalledTimes(1);
expect(scheduler).toHaveBeenCalledWith(expect.any(Function), 1000, 0);
});
it('falls back to setTimeout when no scheduler is provided', () => {
const setTimeoutSpy = vi.spyOn(global, 'setTimeout');
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions
});
triggerReconnection(transport);
expect(setTimeoutSpy).toHaveBeenCalledWith(expect.any(Function), 1000);
});
it('does not use setTimeout when a custom scheduler is provided', () => {
const setTimeoutSpy = vi.spyOn(global, 'setTimeout');
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions,
reconnectionScheduler: vi.fn()
});
triggerReconnection(transport);
expect(setTimeoutSpy).not.toHaveBeenCalled();
});
it('calls the returned cancel function on close()', async () => {
const cancel = vi.fn();
const scheduler: ReconnectionScheduler = vi.fn(() => cancel);
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions,
reconnectionScheduler: scheduler
});
triggerReconnection(transport);
expect(cancel).not.toHaveBeenCalled();
await transport.close();
expect(cancel).toHaveBeenCalledTimes(1);
});
it('tolerates schedulers that return void (no cancel function)', async () => {
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions,
reconnectionScheduler: () => {
/* no return */
}
});
triggerReconnection(transport);
await expect(transport.close()).resolves.toBeUndefined();
});
it('clears the default setTimeout on close() when no scheduler is provided', async () => {
const clearTimeoutSpy = vi.spyOn(global, 'clearTimeout');
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions
});
triggerReconnection(transport);
await transport.close();
expect(clearTimeoutSpy).toHaveBeenCalledTimes(1);
});
it('ignores a late-firing reconnect after close()', async () => {
let capturedReconnect: (() => void) | undefined;
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions,
reconnectionScheduler: reconnect => {
capturedReconnect = reconnect;
}
});
const onerror = vi.fn();
transport.onerror = onerror;
await transport.start();
triggerReconnection(transport);
await transport.close();
capturedReconnect?.();
await vi.runAllTimersAsync();
expect(onerror).not.toHaveBeenCalled();
});
it('still aborts and fires onclose if the cancel function throws', async () => {
transport = new StreamableHTTPClientTransport(new URL('http://localhost:1234/mcp'), {
reconnectionOptions,
reconnectionScheduler: () => () => {
throw new Error('cancel failed');
}
});
const onclose = vi.fn();
transport.onclose = onclose;
await transport.start();
triggerReconnection(transport);
const abortController = transport['_abortController'];
await expect(transport.close()).rejects.toThrow('cancel failed');
expect(abortController?.signal.aborted).toBe(true);
expect(onclose).toHaveBeenCalledTimes(1);
});
});
});