fetch plugin tests: minor improvement

__tests__/plugins/fetch.test.js

@@ -3,25 +3,25 @@ const makeServiceWorkerEnv = require('service-worker-mock');
 global.fetch = require('node-fetch');
 jest.mock('node-fetch')
 
-global.fetch.mockImplementation((url, init) => {
-          const response = new Response(
-                            new Blob(
-                              [JSON.stringify({ test: "success" })],
-                              {type: "application/json"}
-                            ),
-                            {
-                              status: 200,
-                              statusText: "OK",
-                              headers: {
-                                'ETag': 'TestingETagHeader'
-                              },
-                              url: url
-                            });
-          return Promise.resolve(response);
-        });
-
 describe("plugin: fetch", () => {
   beforeEach(() => {
+    global.fetch.mockImplementation((url, init) => {
+        const response = new Response(
+                        new Blob(
+                            [JSON.stringify({ test: "success" })],
+                            {type: "application/json"}
+                        ),
+                        {
+                            status: 200,
+                            statusText: "OK",
+                            headers: {
+                            'ETag': 'TestingETagHeader'
+                            },
+                            url: url
+                        });
+        return Promise.resolve(response);
+    });
+      
     Object.assign(global, makeServiceWorkerEnv());
     jest.resetModules();
     global.LibResilientPluginConstructors = new Map()