feat: Request trailing volume (#29)

src/test/fixtures/rest/users/self/trailing-volume/GET-200.json

@@ -0,0 +1,8 @@
+[
+  {
+    "exchange_volume": "4850.87208838",
+    "product_id": "BTC-EUR",
+    "recorded_at": "2020-01-27T00:05:55.356639Z",
+    "volume": "2.02148248"
+  }
+]

src/user/UserAPI.test.ts

@@ -1,5 +1,6 @@
 import nock from 'nock';
 import verifyPayload from '../test/fixtures/rest/users/self/verify/GET-200.json';
+import trailingVolume from '../test/fixtures/rest/users/self/trailing-volume/GET-200.json';
 import {UserAPI} from './UserAPI';
 
 describe('UserAPI', () => {
@@ -13,6 +14,12 @@ describe('UserAPI', () => {
         return [200, JSON.stringify(verifyPayload)];
       })
       .persist();
+
+    nock(global.REST_URL)
+      .get(`${UserAPI.URL.USERS}/self/trailing-volume`)
+      .query(() => true)
+      .reply(() => [200, JSON.stringify(trailingVolume)])
+      .persist();
   });
 
   describe('verifyAuthentication', () => {
@@ -21,4 +28,11 @@ describe('UserAPI', () => {
       expect(verifiedUser.id).toBe('7cbb4d09b95cee4dea90e9a7');
     });
   });
+
+  describe('getTrailingVolume', () => {
+    it('lists your 30-day trailing volume', async () => {
+      const trailingVolume = await global.client.rest.user.getTrailingVolume();
+      expect(trailingVolume[0].product_id).toBe('BTC-EUR');
+    });
+  });
 });

src/user/UserAPI.ts

@@ -4,6 +4,13 @@ export interface VerifiedUser {
   id: string;
 }
 
+export interface TrailingVolume {
+  exchange_volume: string;
+  product_id: string;
+  recorded_at: string;
+  volume: string;
+}
+
 export class UserAPI {
   static readonly URL: {USERS: string} = {
     USERS: `/users`,
@@ -17,4 +24,17 @@ export class UserAPI {
     const response = await this.apiClient.get<VerifiedUser>(resource);
     return response.data;
   }
+
+  /**
+   * This request will return your 30-day trailing volume for all products of the API key’s profile. This is a cached
+   * value that’s calculated every day at midnight UTC.
+   * @note This endpoint requires either the “view” or “trade” permission
+   * @returns {Promise<TrailingVolume>} Your 30-day trailing volume for all products of the API key’s profile
+   * @see https://docs.pro.coinbase.com/#trailing-volume
+   */
+  async getTrailingVolume(): Promise<TrailingVolume[]> {
+    const resource = `${UserAPI.URL.USERS}/self/trailing-volume`;
+    const response = await this.apiClient.get<TrailingVolume[]>(resource);
+    return response.data;
+  }
 }