api-testing

Overview

Tests target handler behavior directly — call handler(input, ctx), assert on the return value or thrown error. The framework's handler factory (try/catch, formatting, telemetry) is not involved. Use createMockContext from @cyanheads/mcp-ts-core/testing to construct the ctx argument.

Additional exports from /testing: createMockLogger() returns a standalone MockContextLogger for unit-testing code that accepts a ContextLogger directly (services, utilities). createInMemoryStorage(options?) provides a real StorageService backed by InMemoryProvider for testing services that take a StorageService dependency.

Philosophy: Test behavior, not implementation. Refactors should not break tests. Match the repo's existing test layout: fresh scaffolds use tests/, while colocated src/**/*.test.ts files are also supported. Integration tests at I/O boundaries over unit tests of internals.

createMockContext options

import { createMockContext } from '@cyanheads/mcp-ts-core/testing';

createMockContext()                                           // minimal — ctx.state operations throw without tenantId
createMockContext({ tenantId: 'test-tenant' })               // enables ctx.state (tenant-scoped in-memory storage)
createMockContext({ errors: myTool.errors })                 // attaches typed ctx.fail keyed by the contract reasons
createMockContext({ sample: vi.fn().mockResolvedValue(...) }) // with MCP sampling
createMockContext({ elicit: vi.fn().mockResolvedValue(...) }) // with elicitation
createMockContext({ progress: true })                        // with task progress (ctx.progress populated)
createMockContext({ requestId: 'my-id' })                    // override request ID (default: 'test-request-id')
createMockContext({ notifyResourceListChanged: () => {} })   // with resource-list change notifier
createMockContext({ notifyResourceUpdated: (_uri) => {} })   // with resource update notifier
createMockContext({ signal: controller.signal })             // custom AbortSignal
createMockContext({ auth: { clientId: 'test', scopes: [], sub: 'test-user' } }) // with auth context
createMockContext({ uri: new URL('myscheme://item/123') })   // for resource handler testing