Add macro for consistent logging when disabling tests.

ios/testing/earl_grey/disabled_test_macros.h

+// 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.
+
+#ifndef IOS_TESTING_EARL_GREY_DISABLED_TEST_MACROS_H_
+#define IOS_TESTING_EARL_GREY_DISABLED_TEST_MACROS_H_
+
+// A macro that forces an Earl Grey test to pass. It should be used to disable
+// tests that fail due to a bug. This macro should be used when the
+// configuration for which the test should be disabled can only be determined
+// at runtime. Disabling at complile-time is always preferred.

[cmasso1, 2016/08/09 21:00:22]

nit: s/complile/compile

[cmasso1, 2016/08/09 21:00:22]

Also, Isn't it helpful to highlight here what should be used when disabling at
compile time?

[baxley, 2016/08/09 21:05:57]

I thought about it, however we haven't set the precedent of how we'll do it in
Earl Grey. It's likely to be the same as KIF, but I'd rather not put in a
comment that becomes incorrect, and I never remember to update it. This way it
will stay correct, though not as specific as it could be. WDYT?

[baxley, 2016/08/09 21:05:57]

Done.

[cmasso1, 2016/08/09 21:12:12]

Fine by me. Thanks!

+// Example:
+// - (void)testFoo
+// if (base::ios::IsRunningOnIOS10OrLater()) {
+//   EARL_GREY_TEST_DISABLED(@"Disabled on iOS 10.");
+// }
+#define EARL_GREY_TEST_DISABLED(message)                                \

[Eugene But (OOO till 7-30), 2016/08/09 20:47:37]

Optional since KIF also has this problem. This thing will not work as expected:

if (base::ios::IsRunningOnIOS10OrLater())
  EARL_GREY_TEST_DISABLED(@"Disabled on iOS 10.");

How about this?:

while (true) {
  NSLog(@"-- Earl Grey Test Disabled -- %@", message);
  return;
}

[baxley, 2016/08/09 21:05:57]

Nice catch! I don't think not having it in KIF is reason to leave this out.
Done.

+  NSLog(@"-- Earl Grey Test Disabled -- %@", message);                  \
+  return;
+
+// A macro that forces an Earl Grey test to pass. This should be used when a
+// test fails for a specific configuration because it is not supported, but
+// there is no error. This macro should only be used when the configuration for
+// which the test should be disabled can only be determined at runtime.
+// Disabling at compile-time is always preferred.
+// Example:
+// - (void)testFoo
+// if (base::ios::IsRunningOnIOS10OrLater()) {
+//   EARL_GREY_TEST_SKIPPED(@"Test not supported on iOS 10.");
+// }
+#define EARL_GREY_TEST_SKIPPED(message)                                \
+  NSLog(@"-- Earl Grey Test Skipped -- %@", message);                  \
+  return;
+
+#endif  // IOS_TESTING_EARL_GREY_DISABLED_TEST_MACROS_H_