Make Cache Storage tests resilient to execution order

third_party/WebKit/LayoutTests/http/tests/cachestorage/script-tests/cache-storage.js

Index: third_party/WebKit/LayoutTests/http/tests/cachestorage/script-tests/cache-storage.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/cachestorage/script-tests/cache-storage.js b/third_party/WebKit/LayoutTests/http/tests/cachestorage/script-tests/cache-storage.js
index 673cf50f01ca85146983862c9de6bb81967c6002..dd5e39d91e124c9df59bd41d123d81868019a28b 100644
--- a/third_party/WebKit/LayoutTests/http/tests/cachestorage/script-tests/cache-storage.js
+++ b/third_party/WebKit/LayoutTests/http/tests/cachestorage/script-tests/cache-storage.js
@@ -203,20 +203,28 @@ promise_test(function(t) {
   }, 'CacheStorage.delete with nonexistent cache');
 
 promise_test(function(t) {
-    var bad_name = 'unpaired\uD800';
-    var converted_name = 'unpaired\uFFFD'; // Don't create cache with this name.
-    return self.caches.has(converted_name)
+    var unpaired_name = 'unpaired\uD800';
+    var converted_name = 'unpaired\uFFFD';
+
+    // The test assumes that a cache with converted_name does not
+    // exist, but if the implementation fails the test then such
+    // a cache will be created. Start off in a fresh state by
+    // deleting all caches.
+    return delete_all_caches()

[jkarlin, 2016/11/22 18:20:40]

Why not have promise_test run delete_all_caches at the end instead of having to
insert it into tests?

[jsbell, 2016/11/22 18:34:14]

promise_test is generic (part of testharness.js); we could rework all of these
test to go through a common wrapper, but I'd rather do that upstream.

+      .then(function() {
+          return self.caches.has(converted_name);
+      })
       .then(function(cache_exists) {
           assert_false(cache_exists,
                        'Test setup failure: cache should not exist');
       })
-      .then(function() { return self.caches.open(bad_name); })
+      .then(function() { return self.caches.open(unpaired_name); })
       .then(function() { return self.caches.keys(); })
       .then(function(keys) {
-          assert_true(keys.indexOf(bad_name) !== -1,
+          assert_true(keys.indexOf(unpaired_name) !== -1,
                       'keys should include cache with bad name');
       })
-      .then(function() { return self.caches.has(bad_name); })
+      .then(function() { return self.caches.has(unpaired_name); })
       .then(function(cache_exists) {
           assert_true(cache_exists,
                       'CacheStorage names should be not be converted.');