cache plugin test: testing for rejections when content not available (ref. #8)

__tests__/plugins/cache.test.js

@@ -45,6 +45,13 @@ describe("plugin: cache", () => {
     expect(self.LibResilientPlugins[0].name).toEqual('cache');
   });
   
+  test("it should error out if resource is not found", () => {
+    require("../../plugins/cache.js");
+    
+    expect.assertions(1)
+    return expect(self.LibResilientPlugins[0].fetch('https://resilient.is/test.json')).rejects.toThrow(Error)
+  });
+  
   test("it should stash successfully", () => {
     require("../../plugins/cache.js");
     expect.assertions(7);

plugins/cache.js

@@ -29,7 +29,7 @@
                 return cache.match(url)
             })
             .then((response) => {
-                if (typeof response === 'undefined') {
+                if ((typeof response === 'undefined') || (response === null) ) {
                     throw new Error('Resource not found in cache');
                 } else {
                     var msg = 'retrieved cached headers:'