Support passing function for axios client delay (#270)

src/axios.ts

@@ -5,6 +5,8 @@ import {Logger} from 'pino';
 
 import {wrapApiError} from './errors';
 
+type DelayFunction = (error: AxiosError<unknown, any>) => number;
+
 export const DEFAULT_RETRIES = 3;
 export const DEFAULT_RETRY_DELAY = 1000;
 
@@ -30,7 +32,7 @@ export function makeAxiosInstanceWithRetry(
   config?: AxiosRequestConfig,
   logger?: Logger<string>,
   retries = DEFAULT_RETRIES,
-  delay = DEFAULT_RETRY_DELAY
+  delay: number | DelayFunction = DEFAULT_RETRY_DELAY
 ): AxiosInstance {
   const isNetworkError = (error: AxiosError<any>): boolean => {
     return (
@@ -60,7 +62,11 @@ export function makeAxiosInstanceWithRetry(
           wrapApiError(error, `Retry attempt ${retryNumber} of ${retries}`)
         );
       }
-      return retryNumber * delay;
+      if (typeof delay === 'number') {
+        return retryNumber * delay;
+      }
+      return delay(error);
+
     },
     shouldResetTimeout: true,
   });

test/axios.test.ts

@@ -114,4 +114,20 @@ describe('axios', () => {
     );
     mock.done();
   });
+
+  test('delay using function', async () => {
+    const mock = mockPostCode('/hi', 502);
+    const client = sut.makeAxiosInstanceWithRetry(
+      {baseURL: apiUrl},
+      undefined,
+      3,
+      () => {
+        return 50;
+      }
+    );
+    const res = await client.post('/hi');
+    expect(res.status).toBe(200);
+    expect(res.data).toStrictEqual({tenantId: '1'});
+    mock.done();
+  });
 });