Upstream ios/showcase source code.

ios/showcase/test/showcase_test_case.mm

Index: ios/showcase/test/showcase_test_case.mm
diff --git a/ios/showcase/test/showcase_test_case.mm b/ios/showcase/test/showcase_test_case.mm
new file mode 100644
index 0000000000000000000000000000000000000000..e4877f11f752c2f49acdf50c1365ed9b58d52c2a
--- /dev/null
+++ b/ios/showcase/test/showcase_test_case.mm
@@ -0,0 +1,31 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/showcase/test/showcase_test_case.h"
+
+#import <EarlGrey/EarlGrey.h>
+
+#import "base/logging.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@implementation ShowcaseTestCase
+
+// Overrides testInvocations so the set of tests run can be modified, as
+// necessary.
++ (NSArray*)testInvocations {
+  NSError* error = nil;
+  [[EarlGrey selectElementWithMatcher:grey_systemAlertViewShown()]
+      assertWithMatcher:grey_nil()
+                  error:&error];
+  if (error != nil) {
+    LOG(ERROR) << "System alert view is present, so skipping all tests.";
+    return @[];
+  }
+  return [super testInvocations];
+}
+
+@end