Capture plugin

capturePlugin records send lifecycle events into a store and exposes it as client.capture — a typed property added through the plugin extension system. Pair it with the memory adapter to assert exactly what the SDK tried to do, without a network call.

import { createEmailClient } from "@opencoredev/email-sdk";
import { capturePlugin } from "@opencoredev/email-sdk/plugins/capture";
import { memoryProvider } from "@opencoredev/email-sdk/testing";

const email = createEmailClient({
  adapters: [memoryProvider()],
  plugins: [capturePlugin()],
});

await email.send({
  from: "Acme <hello@acme.com>",
  to: "user@example.com",
  subject: "Welcome",
  text: "Your account is ready.",
});

const sent = email.capture.events.find((event) => event.type === "afterSend");
expect(sent?.provider).toBe("memory");
expect(email.capture.events.map((event) => event.type)).toEqual(["beforeSend", "afterSend"]);

email.capture is fully typed — capturePlugin() is an EmailPlugin<{ capture: EmailCaptureStore }>, so the extension flows into the client type with no casts.

What gets captured

Unlike the observability plugin, captured events hold the full, unredacted message — they are meant for test assertions, not production logs.

Reset between tests with email.capture.clear().

Options

capturePlugin(store) is shorthand for capturePlugin({ store }).

Custom client key

clientKey renames the client property, and the type follows the literal you pass:

const email = createEmailClient({
  adapters: [memoryProvider()],
  plugins: [
    capturePlugin({ id: "capture:primary", clientKey: "primaryCapture" }),
    capturePlugin({ id: "capture:audit", clientKey: "auditCapture" }),
  ],
});

email.primaryCapture.events; // typed EmailCaptureStore
email.auditCapture.clear();

Multiple instances need distinct ids (duplicate plugin ids throw) and distinct clientKeys (a second plugin extending the client with an existing key throws).

Share a store

createEmailCaptureStore() creates a store you can hold a reference to directly — useful when the client is built inside a factory and your test only sees the store:

import { capturePlugin, createEmailCaptureStore } from "@opencoredev/email-sdk/plugins/capture";

const store = createEmailCaptureStore();
const email = buildTestClient({ plugins: [capturePlugin(store)] });

await email.send(message);
expect(store.events).toHaveLength(2);

Capture vs memory adapter

They answer different questions: memoryProvider() replaces the network so nothing real sends, while capturePlugin() records what the pipeline did — including retries and errors the adapter alone cannot show. Most tests use both. See Test email behavior for the full testing setup.