first actual test for alt-fetch

__tests__/plugins/alt-fetch.test.js

@@ -1,18 +1,88 @@
 const makeServiceWorkerEnv = require('service-worker-mock');
 
+global.fetch = require('node-fetch');
+jest.mock('node-fetch')
+
+/*
+ * we need a Promise.any() polyfill
+ * so here it is
+ * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/any
+ * 
+ * TODO: remove once Promise.any() is implemented broadly
+ */
+if (typeof Promise.any === 'undefined') {
+    Promise.any = async (promises) => {
+        // Promise.all() is the polar opposite of Promise.any()
+        // in that it returns as soon as there is a first rejection
+        // but without it, it returns an array of resolved results
+        return Promise.all(
+            promises.map(p => {
+                return new Promise((resolve, reject) =>
+                    // swap reject and resolve, so that we can use Promise.all()
+                    // and get the result we need
+                    Promise.resolve(p).then(reject, resolve)
+                );
+            })
+        // now, swap errors and values back
+        ).then(
+            err => Promise.reject(err),
+            val => Promise.resolve(val)
+        );
+    };
+}
+
 describe("plugin: alt-fetch", () => {
+  
   beforeEach(() => {
     Object.assign(global, makeServiceWorkerEnv());
     jest.resetModules();
     self.LibResilientPlugins = new Array()
     self.LibResilientConfig = {
         plugins: {
-            'alt-fetch':{}
+            'alt-fetch':{
+              endpoints: [
+                'https://alt.resilient.is/test.json',
+                'https://error.resilientis/test.json',
+                'https://timeout.resilientis/test.json'
+              ]
+            }
         }
     }
+    self.log = function(component, ...items) {
+        console.debug(component + ' :: ', ...items)
+    }
   })
+  
   test("it should register in LibResilientPlugins", () => {
     require("../../plugins/alt-fetch.js");
     expect(self.LibResilientPlugins[0].name).toEqual('alt-fetch');
   });
+  
+  test("it should fetch the content", async () => {
+    const altFetch = require("../../plugins/alt-fetch.js");
+    
+    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);
+        });
+    
+    const response = await self.LibResilientPlugins[0].fetch('https://resilient.is/test.json');
+    
+    expect(fetch).toHaveBeenCalled();
+    expect(await response.json()).toEqual({test: "success"})
+    expect(response.url).toEqual('https://resilient.is/test.json')
+  })
+  
 });

plugins/alt-fetch.js

@@ -71,7 +71,7 @@
         // we don't want to modify the original endpoints array
         var sourceEndpoints = [...config.endpoints]
         
-        // if we have fewer than the configured concurrency, use all of them
+        // if we have fewer than the configured concurrency or just as many, use all of them
         if (sourceEndpoints.length <= config.concurrency) {
             var useEndpoints = sourceEndpoints
         // otherwise get `config.concurrency` endpoints at random