[SDK-2750] Expose mfa_token from the mfa_required error when getting new tokens

__tests__/http.test.ts

@@ -1,5 +1,6 @@
 import fetch from 'unfetch';
-import { switchFetch } from '../src/http';
+import { MfaRequiredError } from '../src/errors';
+import { switchFetch, getJSON } from '../src/http';
 
 jest.mock('../src/worker/token.worker');
 jest.mock('unfetch');
@@ -19,3 +20,32 @@ describe('switchFetch', () => {
     expect(clearTimeout).toBeCalledTimes(1);
   });
 });
+
+describe('getJson', () => {
+  it('throws MfaRequiredError when mfa_required is returned', async () => {
+    mockUnfetch.mockImplementation(() =>
+      Promise.resolve({
+        ok: false,
+        json: () => Promise.resolve({ error: 'mfa_required' })
+      })
+    );
+
+    await expect(
+      getJSON('https://test.com/', null, null, null, {}, undefined)
+    ).rejects.toBeInstanceOf(MfaRequiredError);
+  });
+
+  it('reads the mfa_token when mfa_required is returned', async () => {
+    mockUnfetch.mockImplementation(() =>
+      Promise.resolve({
+        ok: false,
+        json: () =>
+          Promise.resolve({ error: 'mfa_required', mfa_token: '1234' })
+      })
+    );
+
+    await expect(
+      getJSON('https://test.com/', null, null, null, {}, undefined)
+    ).rejects.toHaveProperty('mfa_token', '1234');
+  });
+});

src/errors.ts

@@ -66,3 +66,18 @@ export class PopupCancelledError extends GenericError {
     Object.setPrototypeOf(this, PopupCancelledError.prototype);
   }
 }
+
+/**
+ * Error thrown when the token exchange results in a `mfa_required` error
+ */
+export class MfaRequiredError extends GenericError {
+  constructor(
+    error: string,
+    error_description: string,
+    public mfa_token: string
+  ) {
+    super(error, error_description);
+    //https://github.com/Microsoft/TypeScript-wiki/blob/master/Breaking-Changes.md#extending-built-ins-like-error-array-and-map-may-no-longer-work
+    Object.setPrototypeOf(this, MfaRequiredError.prototype);
+  }
+}

src/http.ts

@@ -7,7 +7,7 @@ import {
 
 import { sendMessage } from './worker/worker.utils';
 import { FetchOptions } from './global';
-import { GenericError } from './errors';
+import { GenericError, MfaRequiredError } from './errors';
 
 export const createAbortController = () => new AbortController();
 
@@ -133,16 +133,20 @@ export async function getJSON<T>(
   }
 
   const {
-    json: { error, error_description, ...success },
+    json: { error, error_description, ...data },
     ok
   } = response;
 
   if (!ok) {
     const errorMessage =
       error_description || `HTTP error. Unable to fetch ${url}`;
 
+    if (error === 'mfa_required') {
+      throw new MfaRequiredError(error, errorMessage, data.mfa_token);
+    }
+
     throw new GenericError(error || 'request_error', errorMessage);
   }
 
-  return success;
+  return data;
 }