[ServiceWorker] Tests for Cache

LayoutTests/http/tests/serviceworker/resources/worker-testharness.js

 /*
  * worker-test-harness should be considered a temporary polyfill around
  * testharness.js for supporting Service Worker based tests. It should not be
  * necessary once the test harness is able to drive worker based tests natively.
  * See https://github.com/w3c/testharness.js/pull/82 for status of effort to
  * update upstream testharness.js. Once the upstreaming is complete, tests that
  * reference worker-test-harness should be updated to directly import
  * testharness.js.
  */
 
@@ skipping 54 matching lines @@
             var message = {
               type: 'complete',
               tests: results.tests,
               status: results.status
             };
             port.postMessage(message);
           });
       }
     });
 })();
+
+(function() {
+  var next_cache_index = 1;
+
+  // Returns a promise that resolves to a newly created Cache object. The
+  // returned Cache will be destroyed when |test| completes.
+  function create_temporary_cache(test) {
+    var uniquifier = String(++next_cache_index);
+    var cache_name = self.location.pathname + '/' + uniquifier;
+
+    test.add_cleanup(function() {
+        self.caches.delete(cache_name);
+      });
+
+    return self.caches.delete(cache_name)
+      .then(function() {
+          return self.caches.open(cache_name);
+        });
+  }
+
+  self.create_temporary_cache = create_temporary_cache;
+})();
+
+// Runs |test_function| with a temporary unique Cache passed in as the only
+// argument. The function is run as a part of Promise chain owned by
+// promise_test(). As such, it is expected to behave in a manner identical (with
+// the exception of the argument) to a function passed into promise_test().
+//
+// E.g.:
+//    cache_test(function(cache) {
+//      // Do something with |cache|, which is a Cache object.
+//    }, "Some Cache test");
+function cache_test(test_function, description) {
+  promise_test(function(test) {
+    return create_temporary_cache(test)
+        .then(test_function);
+  }, description);
+}