jsonrpc: SDK serving surface as plugins (dsh-jsonrpc + dsh-jsonrpc-agent)

packages/ui/jsonrpc/tests/transport.spec.ts

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+import { once } from 'node:events'
+import { PassThrough } from 'node:stream'
+import { describe, expect, it } from 'vitest'
+import { JsonRpcLineTransport } from '../src/index.ts'
+
+function transportPair() {
+  const aToB = new PassThrough()
+  const bToA = new PassThrough()
+  const a = new JsonRpcLineTransport(bToA, aToB)
+  const b = new JsonRpcLineTransport(aToB, bToA)
+  return { a, b, aToB, bToA }
+}
+
+describe('JsonRpcLineTransport', () => {
+  it('supports bidirectional requests and notifications over newline-delimited JSON-RPC', async () => {
+    const { a, b } = transportPair()
+    const notifications: Record<string, unknown>[] = []
+
+    a.onRequest(async (method, params) => {
+      expect(method).toBe('echo')
+      return { echoed: params }
+    })
+    b.onNotification((method, params) => {
+      notifications.push({ method, params })
+    })
+    a.start()
+    b.start()
+
+    const response = await b.request('echo', { value: 42 })
+    expect(response).toEqual({ echoed: { value: 42 } })
+
+    a.notify('session.finished', { sessionId: 'main', status: 'ok' })
+    a.notify('heartbeat')
+    await new Promise(resolve => setTimeout(resolve, 10))
+    expect(notifications).toEqual([
+      { method: 'session.finished', params: { sessionId: 'main', status: 'ok' } },
+      { method: 'heartbeat', params: {} },
+    ])
+
+    a.close()
+    b.close()
+  })
+
+  it('reports JSON-RPC request errors from the remote peer', async () => {
+    const { a, b } = transportPair()
+    a.onRequest(async () => {
+      throw new Error('handler boom')
+    })
+    a.start()
+    b.start()
+
+    await expect(b.request('explode', {})).rejects.toThrow('handler boom')
+
+    a.close()
+    b.close()
+  })
+
+  it('stringifies non-Error request handler failures', async () => {
+    const { a, b } = transportPair()
+    a.onRequest(async () => {
+      throw 'string boom'
+    })
+    a.start()
+    b.start()
+
+    await expect(b.request('explode-string', {})).rejects.toThrow('string boom')
+
+    a.close()
+    b.close()
+  })
+
+  it('reports method-not-found when no request handler is installed', async () => {
+    const { a, b } = transportPair()
+    a.start()
+    b.start()
+
+    await expect(b.request('missing', {})).rejects.toThrow('method not found: missing')
+
+    a.close()
+    b.close()
+  })
+
+  it('normalizes non-object request params and ignores notifications without a handler', async () => {
+    const { aToB, bToA, b } = transportPair()
+    const seen: Record<string, unknown>[] = []
+    b.onRequest(async (method, params) => {
+      seen.push({ method, params })
+      return { ok: true }
+    })
+    b.start()
+
+    aToB.write('{"jsonrpc":"2.0","method":"ignored"}\n')
+    aToB.write('{"jsonrpc":"2.0","id":7,"method":"array-params","params":[]}\n')
+    const chunk = (await once(bToA, 'data'))[0] as Buffer | string
+
+    expect(seen).toEqual([{ method: 'array-params', params: {} }])
+    expect(JSON.parse(String(chunk))).toEqual({ jsonrpc: '2.0', id: 7, result: { ok: true } })
+    b.close()
+  })
+
+  it('ignores malformed frames and accepts notifications without params', async () => {
+    const { aToB, b } = transportPair()
+    const notifications: Record<string, unknown>[] = []
+    b.onNotification((method, params) => {
+      notifications.push({ method, params })
+    })
+    b.start()
+    b.start()
+
+    aToB.write('not json\n')
+    aToB.write('\n')
+    aToB.write('null\n')
+    aToB.write('{"jsonrpc":"2.0","params":{}}\n')
+    aToB.write('{"jsonrpc":"2.0","method":"tick"}\n')
+    aToB.emit('data', '{"jsonrpc":"2.0","method":"string-chunk"}\n')
+    await new Promise(resolve => setTimeout(resolve, 10))
+
+    expect(notifications).toEqual([
+      { method: 'tick', params: {} },
+      { method: 'string-chunk', params: {} },
+    ])
+    b.close()
+  })
+
+  it('rejects pending requests when the input closes', async () => {
+    const { aToB, b } = transportPair()
+    b.start()
+
+    const pending = b.request('never-replies', {})
+    aToB.end()
+
+    await expect(pending).rejects.toThrow('JSON-RPC input closed')
+    b.close()
+  })
+
+  it('rejects pending requests when the input errors', async () => {
+    const { aToB, b } = transportPair()
+    b.start()
+
+    const pending = b.request('never-replies', {})
+    aToB.emit('error', new Error('input broke'))
+
+    await expect(pending).rejects.toThrow('input broke')
+    b.close()
+  })
+
+  it('rejects pending requests when the transport closes', async () => {
+    const { b } = transportPair()
+
+    const pending = b.request('never-replies', {})
+    b.close()
+
+    await expect(pending).rejects.toThrow('JSON-RPC transport closed')
+  })
+
+  it('rejects a request when writing the frame throws', async () => {
+    const input = new PassThrough()
+    const output = {
+      write() {
+        throw new Error('write exploded')
+      },
+    }
+    const transport = new JsonRpcLineTransport(input, output as never)
+
+    await expect(transport.request('write-fails', {})).rejects.toThrow('write exploded')
+  })
+
+  it('stringifies non-Error write failures', async () => {
+    const input = new PassThrough()
+    const output = {
+      write() {
+        throw 'write string'
+      },
+    }
+    const transport = new JsonRpcLineTransport(input, output as never)
+
+    await expect(transport.request('write-fails', {})).rejects.toThrow('write string')
+  })
+
+  it('uses a fallback message for malformed JSON-RPC error responses', async () => {
+    const { aToB, bToA, b } = transportPair()
+    b.start()
+
+    const pending = b.request('remote-error', {})
+    const requestChunk = (await once(bToA, 'data'))[0] as Buffer | string
+    const request = JSON.parse(String(requestChunk)) as { id: string }
+    aToB.write(`${JSON.stringify({ jsonrpc: '2.0', id: request.id, error: {} })}\n`)
+
+    await expect(pending).rejects.toThrow('JSON-RPC error')
+    b.close()
+  })
+
+  it('ignores responses that do not match a pending request', async () => {
+    const { aToB, b } = transportPair()
+    b.start()
+
+    aToB.write('{"jsonrpc":"2.0","id":"unknown","result":{"ignored":true}}\n')
+    await new Promise(resolve => setTimeout(resolve, 10))
+
+    b.close()
+  })
+})