jest: mock fetch kinda working

__tests__/plugins/fetch.test.js

@@ -1,5 +1,9 @@
 const makeServiceWorkerEnv = require('service-worker-mock');
 
+const fetch = require('jest-fetch-mock');
+fetch.enableMocks()
+jest.setMock('node-fetch', fetch);
+
 describe("plugin: fetch", () => {
   beforeEach(() => {
     Object.assign(global, makeServiceWorkerEnv());
@@ -10,9 +14,21 @@ describe("plugin: fetch", () => {
             'fetch':{}
         }
     }
+    self.log = function(component, ...items) {
+        console.debug(component + ' :: ', ...items)
+    }
   })
   test("it should register in LibResilientPlugins", () => {
     require("../../plugins/fetch.js");
     expect(self.LibResilientPlugins[0].name).toEqual('fetch');
   });
+  
+  test("it should return data from fetch()", async () => {
+    require("../../plugins/fetch.js");
+    
+    fetch.mockResponse(JSON.stringify({test: "success"}));
+
+    const returnedJSON = await self.LibResilientPlugins[0].fetch('https://resilient.is/test.json');
+    expect(returnedJSON).toEqual({test: "success"})
+  });
 });

package-lock.json

@@ -1250,6 +1250,15 @@
         "safe-buffer": "5.1.2"
       }
     },
+    "cross-fetch": {
+      "version": "3.1.4",
+      "resolved": "https://registry.npmjs.org/cross-fetch/-/cross-fetch-3.1.4.tgz",
+      "integrity": "sha512-1eAtFWdIubi6T4XPy6ei9iUFoKpUkIF971QLN8lIvvvwueI65+Nw5haMNKUwfJxabqlIIDODJKGrQ66gxC0PbQ==",
+      "dev": true,
+      "requires": {
+        "node-fetch": "2.6.1"
+      }
+    },
     "cross-spawn": {
       "version": "7.0.3",
       "resolved": "https://registry.npmjs.org/cross-spawn/-/cross-spawn-7.0.3.tgz",
@@ -2273,6 +2282,16 @@
         "jest-util": "27.0.6"
       }
     },
+    "jest-fetch-mock": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/jest-fetch-mock/-/jest-fetch-mock-3.0.3.tgz",
+      "integrity": "sha512-Ux1nWprtLrdrH4XwE7O7InRY6psIi3GOsqNESJgMJ+M5cv4A8Lh7SN9d2V2kKRZ8ebAfcd1LNyZguAOb6JiDqw==",
+      "dev": true,
+      "requires": {
+        "cross-fetch": "3.1.4",
+        "promise-polyfill": "8.2.0"
+      }
+    },
     "jest-get-type": {
       "version": "27.0.6",
       "resolved": "https://registry.npmjs.org/jest-get-type/-/jest-get-type-27.0.6.tgz",
@@ -2890,6 +2909,12 @@
       "integrity": "sha1-Sr6/7tdUHywnrPspvbvRXI1bpPc=",
       "dev": true
     },
+    "node-fetch": {
+      "version": "2.6.1",
+      "resolved": "https://registry.npmjs.org/node-fetch/-/node-fetch-2.6.1.tgz",
+      "integrity": "sha512-V4aYg89jEoVRxRb2fJdAg8FHvI7cEyYdVAh94HH0UIK8oJxUfkjlDQN9RbMx+bEjP7+ggMiFRprSti032Oipxw==",
+      "dev": true
+    },
     "node-int64": {
       "version": "0.4.0",
       "resolved": "https://registry.npmjs.org/node-int64/-/node-int64-0.4.0.tgz",
@@ -3086,6 +3111,12 @@
       "integrity": "sha512-7PiHtLll5LdnKIMw100I+8xJXR5gW2QwWYkT6iJva0bXitZKa/XMrSbdmg3r2Xnaidz9Qumd0VPaMrZlF9V9sA==",
       "dev": true
     },
+    "promise-polyfill": {
+      "version": "8.2.0",
+      "resolved": "https://registry.npmjs.org/promise-polyfill/-/promise-polyfill-8.2.0.tgz",
+      "integrity": "sha512-k/TC0mIcPVF6yHhUvwAp7cvL6I2fFV7TzF1DuGPI8mBh4QQazf36xCKEHKTZKRysEoTQoQdKyP25J8MPJp7j5g==",
+      "dev": true
+    },
     "prompts": {
       "version": "2.4.1",
       "resolved": "https://registry.npmjs.org/prompts/-/prompts-2.4.1.tgz",

package.json

@@ -2,6 +2,7 @@
   "devDependencies": {
     "eslint": "^7.32.0",
     "jest": "^27.0.6",
+    "jest-fetch-mock": "^3.0.3",
     "service-worker-mock": "^2.0.5"
   },
   "dependencies": {}