Add simplistic exponential backoff retry

index.js

@@ -22,7 +22,16 @@ class rpRetry {
                     logger.info(`Encountered error ${err.message} for ${options.method} request to ${options.uri}, retry count ${tryCount}`);
                     tryCount -= 1;
                     if (tryCount) {
-                        return fetchDataWithRetry(tryCount);
+                        let delay = options.delay || 100; // default delay between retries
+                        if (options.factor) {
+                            delay *= options.factor;
+                        }
+                        return new Promise((resolve, reject) => {
+                            setTimeout(() => {
+                                logger.debug(`waiting for ${delay} ms before next retry for ${options.uri}`);
+                                resolve(fetchDataWithRetry(tryCount));
+                            }, delay);
+                        });
                     }
                     return Promise.reject(err);
                 });

test/index.test.js

@@ -102,4 +102,18 @@ describe('request-promise-retry', function () {
                 expect(data.error).equal(undefined);
             });
     });
+    it('should pass, retry with exponential backoff', () => {
+        // failure should take a bit of time to happen
+        const startTime = new Date();
+        return rp({
+            uri: 'http://adadadadad.com/',
+            method: 'GET',
+            retry: 5,
+            delay: 200,
+            factor: 1.1 //
+        })
+            .catch(error => {
+                expect(new Date() - startTime).to.be.above((5 - 1) * 200);
+            });
+    });
 });