feat(plugins): Adds Mailchimp newsletter subscription

packages/medusa-plugin-mailchimp/src/services/__tests__/mailchimp.js

@@ -0,0 +1,21 @@
+const MailchimpMock = jest.fn().mockImplementation(() => {
+  return {
+    subscribeNewsletter: jest.fn().mockReturnValue(Promise.resolve("success")),
+  }
+})
+
+describe("MailchimpService", () => {
+  describe("newsletterSubscribe", () => {
+    let result
+    beforeAll(async () => {
+      jest.clearAllMocks()
+      const mailchimpService = new MailchimpMock()
+
+      result = await mailchimpService.subscribeNewsletter("medusa@medusa.com")
+    })
+
+    it("resolves successfully", () => {
+      expect(result).toEqual("success")
+    })
+  })
+})

packages/medusa-plugin-mailchimp/src/services/mailchimp.js

@@ -0,0 +1,39 @@
+import { BaseService } from "medusa-interfaces"
+import Mailchimp from "mailchimp-api-v3"
+
+class MailchimpService extends BaseService {
+  /**
+   * @param {Object} options - options defined in `medusa-config.js`
+   *    e.g.
+   *    {
+   *      api_key: Mailchimp api key
+   *      newsletter_list_id: "123456789"
+   *    }
+   */
+  constructor({}, options) {
+    super()
+
+    this.options_ = options
+
+    this.mailchimp_ = new Mailchimp(options.api_key)
+  }
+
+  /**
+   * Subscribes an email to a newsletter.
+   * @param {string} email - email to use for the subscription
+   * @param {Object} data - additional data (see https://mailchimp.com/developer/api/marketing/list-members/add-member-to-list/)
+   * @return {Promise} result of newsletter subscription
+   */
+  async subscribeNewsletter(email, data) {
+    return this.mailchimp_.post(
+      `/lists/${this.options_.newsletter_list_id}/members`,
+      {
+        email_address: email,
+        status: "subscribed",
+        ...data,
+      }
+    )
+  }
+}
+
+export default MailchimpService