MCP: wait-for-ready + transient retry on first call; add tests #6894
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,180 @@ | ||
| import type { ClineProvider } from "../../../core/webview/ClineProvider" | ||
| import { McpHub } from "../McpHub" | ||
| import { vi, describe, it, expect, beforeEach } from "vitest" | ||
| import fs from "fs/promises" | ||
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| // Minimal VSCode and FS mocks to keep constructor side-effects inert | ||
| vi.mock("vscode", () => ({ | ||
| workspace: { | ||
| createFileSystemWatcher: vi.fn().mockReturnValue({ | ||
| onDidChange: vi.fn(), | ||
| onDidCreate: vi.fn(), | ||
| onDidDelete: vi.fn(), | ||
| dispose: vi.fn(), | ||
| }), | ||
| onDidChangeWorkspaceFolders: vi.fn(), | ||
| workspaceFolders: [], | ||
| }, | ||
| window: { | ||
| showErrorMessage: vi.fn(), | ||
| showInformationMessage: vi.fn(), | ||
| showWarningMessage: vi.fn(), | ||
| }, | ||
| Disposable: { | ||
| from: vi.fn(), | ||
| }, | ||
| })) | ||
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| vi.mock("fs/promises", () => ({ | ||
| default: { | ||
| access: vi.fn().mockResolvedValue(undefined), | ||
| writeFile: vi.fn().mockResolvedValue(undefined), | ||
| readFile: vi.fn().mockResolvedValue("{}"), | ||
| unlink: vi.fn().mockResolvedValue(undefined), | ||
| rename: vi.fn().mockResolvedValue(undefined), | ||
| lstat: vi.fn().mockResolvedValue({ isDirectory: () => true }), | ||
| mkdir: vi.fn().mockResolvedValue(undefined), | ||
| }, | ||
| access: vi.fn().mockResolvedValue(undefined), | ||
| writeFile: vi.fn().mockResolvedValue(undefined), | ||
| readFile: vi.fn().mockResolvedValue("{}"), | ||
| unlink: vi.fn().mockResolvedValue(undefined), | ||
| rename: vi.fn().mockResolvedValue(undefined), | ||
| lstat: vi.fn().mockResolvedValue({ isDirectory: () => true }), | ||
| mkdir: vi.fn().mockResolvedValue(undefined), | ||
| })) | ||
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| describe("McpHub transient-retry and readiness", () => { | ||
|
Contributor
Author
There was a problem hiding this comment. Great test coverage for the happy path! Consider adding edge case tests: What happens when waitForServerReady times out? What happens on the second retry failure (should not retry a third time)? Error handling when connection is removed during the wait period. These would help ensure the retry logic is robust under various failure scenarios. |
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| let mcpHub: McpHub | ||
| let mockProvider: Partial<ClineProvider> | ||
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| beforeEach(() => { | ||
| vi.clearAllMocks() | ||
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| // Prevent constructor from kicking off async initialization that races our injected connections | ||
| vi.spyOn(McpHub.prototype as any, "initializeGlobalMcpServers").mockResolvedValue(undefined as any) | ||
| vi.spyOn(McpHub.prototype as any, "initializeProjectMcpServers").mockResolvedValue(undefined as any) | ||
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| mockProvider = { | ||
| ensureSettingsDirectoryExists: vi.fn().mockResolvedValue("/mock/settings/path"), | ||
| ensureMcpServersDirectoryExists: vi.fn().mockResolvedValue("/mock/settings/path"), | ||
| postMessageToWebview: vi.fn().mockResolvedValue(undefined), | ||
| getState: vi.fn().mockResolvedValue({ mcpEnabled: true }), | ||
| context: { | ||
| subscriptions: [], | ||
| workspaceState: {} as any, | ||
| globalState: {} as any, | ||
| secrets: {} as any, | ||
| extensionUri: { fsPath: "/test/path" } as any, | ||
| extensionPath: "/test/path", | ||
| asAbsolutePath: (p: string) => p, | ||
| globalStorageUri: { fsPath: "/test/global" } as any, | ||
| globalStoragePath: "/test/global", | ||
| extension: { | ||
| packageJSON: { version: "1.0.0" }, | ||
| } as any, | ||
| } as any, | ||
| } | ||
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| // Keep global config empty so constructor does not attempt to connect anything | ||
| vi.mocked(fs.readFile).mockResolvedValue("{}") | ||
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| mcpHub = new McpHub(mockProvider as ClineProvider) | ||
| }) | ||
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| it("retries once on transient -32000 'Connection closed' for tools/call", async () => { | ||
| // Prepare a connected connection | ||
| const firstError: any = new Error("Connection closed") | ||
| firstError.code = -32000 | ||
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| const request = vi | ||
| .fn() | ||
| // First call: throw transient | ||
| .mockRejectedValueOnce(firstError) | ||
| // Second call: succeed | ||
| .mockResolvedValueOnce({ content: [{ type: "text", text: "ok" }] }) | ||
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| // Inject a connected connection directly | ||
| ;(mcpHub as any).connections = [ | ||
| { | ||
| type: "connected", | ||
| server: { | ||
| name: "retry-server", | ||
| config: JSON.stringify({ type: "stdio", command: "node", timeout: 60 }), | ||
| status: "connected", | ||
| source: "global", | ||
| errorHistory: [], | ||
| }, | ||
| client: { request } as any, | ||
| transport: {} as any, | ||
| }, | ||
| ] | ||
|
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| const result = await mcpHub.callTool("retry-server", "do_something", { a: 1 }) | ||
| expect(result).toBeTruthy() | ||
| expect(request).toHaveBeenCalledTimes(2) | ||
| }) | ||
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| it("retries once on transient -32000 'Connection closed' for resources/read", async () => { | ||
| const firstError: any = new Error("Connection closed before response") | ||
| firstError.code = -32000 | ||
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| const request = vi | ||
| .fn() | ||
| .mockRejectedValueOnce(firstError) | ||
| .mockResolvedValueOnce({ contents: [{ type: "text", text: "resource" }] }) | ||
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| ;(mcpHub as any).connections = [ | ||
| { | ||
| type: "connected", | ||
| server: { | ||
| name: "retry-server", | ||
| config: JSON.stringify({ type: "stdio", command: "node", timeout: 60 }), | ||
| status: "connected", | ||
| source: "global", | ||
| errorHistory: [], | ||
| }, | ||
| client: { request } as any, | ||
| transport: {} as any, | ||
| }, | ||
| ] | ||
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| const result = await mcpHub.readResource("retry-server", "file:///tmp/x.txt") | ||
| expect(result).toBeTruthy() | ||
| expect(request).toHaveBeenCalledTimes(2) | ||
| }) | ||
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| it("waits for server to become connected before first tool call", async () => { | ||
| // Start 'connecting' and then flip to 'connected' shortly after | ||
| const request = vi.fn().mockResolvedValue({ content: [{ type: "text", text: "ok" }] }) | ||
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| const connection: any = { | ||
| type: "connected", | ||
| server: { | ||
| name: "slow-server", | ||
| config: JSON.stringify({ type: "stdio", command: "node", timeout: 60 }), | ||
| status: "connecting", | ||
| source: "global", | ||
| errorHistory: [], | ||
| }, | ||
| client: { request }, | ||
| transport: {}, | ||
| } | ||
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| ;(mcpHub as any).connections = [connection] | ||
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| // Flip status to 'connected' after 100ms | ||
| setTimeout(() => { | ||
| connection.server.status = "connected" | ||
| }, 100) | ||
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| const start = Date.now() | ||
| const result = await mcpHub.callTool("slow-server", "ping", {}) | ||
| const elapsed = Date.now() - start | ||
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| expect(result).toBeTruthy() | ||
| expect(request).toHaveBeenCalledTimes(1) | ||
| // Should have waited at least ~100ms before making the request | ||
| expect(elapsed).toBeGreaterThanOrEqual(90) | ||
| }) | ||
| }) | ||
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Is this intentional? The connection check happens outside the loop, which could lead to a race condition if the connection is removed between the initial check and entering the loop. Consider moving the findConnection call inside the loop for safer operation.