add correct interceptors usage

lib/mock-axios-types.ts

@@ -9,7 +9,7 @@ export interface HttpResponse {
 }
 
 interface Interceptor {
-    use: jest.Mock<number, [any?, any?]>;
+    use: jest.Mock<number, [onFulfilled?: (value: any) => any | Promise<any>, onRejected?: (error: any) => any]>;
     eject: jest.Mock<void, [number]>;
 }
 
@@ -18,6 +18,11 @@ interface Interceptors {
     response: Interceptor;
 }
 
+export interface InterceptorsStack {
+    onFulfilled?(value: any): any | Promise<any>;
+    onRejected?(error: any): any;
+}
+
 interface AxiosDefaults {
     headers: any;
 }

lib/mock-axios.ts

@@ -7,19 +7,30 @@
  */
 
 import {jest} from '@jest/globals';
- 
- import { SynchronousPromise, UnresolvedSynchronousPromise } from "synchronous-promise";
+
+import { SynchronousPromise, UnresolvedSynchronousPromise } from "synchronous-promise";
 import Cancel from "./cancel/Cancel";
 import CancelToken from "./cancel/CancelToken";
 import {
     AxiosMockQueueItem,
     AxiosMockRequestCriteria,
     AxiosMockType,
     HttpResponse,
+    InterceptorsStack,
 } from "./mock-axios-types";
 
 /** a FIFO queue of pending request */
 const _pending_requests: AxiosMockQueueItem[] = [];
+const _responseInterceptors: InterceptorsStack[] = [];
+const _requestInterceptors: InterceptorsStack[] = [];
+
+const processInterceptors = (data: any, stack: InterceptorsStack[], type: keyof InterceptorsStack) => {
+    return stack.map(({[type]: interceptor}) => interceptor)
+        .filter((interceptor) => !!interceptor)
+        .reduce((_result, next) => {
+            return next(_result);
+        }, data);
+}
 
 const _newReq: (config?: any) => UnresolvedSynchronousPromise<any> = (config: any = {}, actualConfig: any = {}) => {
     if(typeof config === 'string') {
@@ -42,13 +53,15 @@ const _newReq: (config?: any) => UnresolvedSynchronousPromise<any> = (config: an
         })
     }
 
-    _pending_requests.push({
+    const requestConfig = processInterceptors({
         config,
         data,
         method,
         promise,
         url
-    });
+    }, _requestInterceptors, 'onFulfilled');
+
+    _pending_requests.push(requestConfig);
     return promise;
 };
 
@@ -93,15 +106,23 @@ MockAxios.create = jest.fn(() => MockAxios);
 MockAxios.interceptors = {
     request: {
         // @ts-ignore
-        use: jest.fn(),
+        use: jest.fn((onFulfilled, onRejected) => {
+            return _requestInterceptors.push({ onFulfilled, onRejected })
+        }),
         // @ts-ignore
-        eject: jest.fn(),
+        eject: jest.fn((position: number) => {
+            _requestInterceptors.splice(position - 1, 1);
+        }),
     },
     response: {
         // @ts-ignore
-        use: jest.fn(),
+        use: jest.fn((onFulfilled, onRejected) => {
+            return _responseInterceptors.push({onFulfilled, onRejected});
+        }),
         // @ts-ignore
-        eject: jest.fn(),
+        eject: jest.fn((position: number) => {
+            _responseInterceptors.splice(position - 1, 1);
+        }),
     },
 };
 
@@ -188,8 +209,10 @@ MockAxios.mockResponse = (
         return;
     }
 
+    const result = processInterceptors(response, _responseInterceptors, 'onFulfilled');
+
     // resolving the Promise with the given response data
-    promise.resolve(response);
+    promise.resolve(result);
 };
 
 MockAxios.mockResponseFor = (
@@ -228,8 +251,10 @@ MockAxios.mockError = (
         error.isAxiosError = true;
     }
 
+    const result = processInterceptors(error, _responseInterceptors, 'onRejected');
+
     // resolving the Promise with the given error
-    promise.reject(error);
+    promise.reject(result);
 };
 
 MockAxios.isAxiosError = (payload) => (typeof payload === 'object') && (payload.isAxiosError === true);