Add custom fetch support as fetch config option

package.json

@@ -30,10 +30,11 @@
     "eslint": "^6.8.0",
     "eslint-config-developit": "^1.1.1",
     "file-loader": "^5.0.2",
+    "isomorphic-fetch": "^2.2.1",
     "jest": "^24.9.0",
     "karmatic": "^1.4.0",
     "microbundle": "^0.11.0",
     "sinon": "^8.0.4",
     "webpack": "^4.41.5"
   }
-}
+}

src/index.js

@@ -142,7 +142,8 @@ export default (function create(defaults) {
 				}
 			}
 		}
-
+
+		const fetchFunc = options.fetch || fetch;
 		const customHeaders = {};
 
 		if (data && typeof data === 'object') {
@@ -168,7 +169,7 @@ export default (function create(defaults) {
 		const response = {};
 		response.config = config;
 
-		return fetch(url, {
+		return fetchFunc(url, {
 			method: options.method,
 			body: data,
 			headers: deepMerge(options.headers, customHeaders, true)

test/index.test.js

@@ -15,6 +15,7 @@
 import axios from '../src/index.js';
 import textExample from 'file-loader!./fixtures/example.txt';
 import jsonExample from 'file-loader!./fixtures/example.json.txt';
+import fetch from 'isomorphic-fetch';
 
 describe('redaxios', () => {
 	it('smoke test', () => {
@@ -73,4 +74,13 @@ describe('redaxios', () => {
 			window.fetch = oldFetch;
 		}
 	});
+
+	it('should accept a custom fetch implementation', async () => {
+		const req = axios.get(jsonExample, { fetch });
+		expect(req).toBeInstanceOf(Promise);
+		const res = await req;
+		expect(res).toBeInstanceOf(Object);
+		expect(res.status).toEqual(200);
+		expect(JSON.parse(res.data)).toEqual({ hello: 'world' });
+	});
 });