coro helper for FAIL() gtest macro

Summary: Need this to migrate CO_TEST using FAIL() fully on coroutines.

Reviewed By: ispeters

Differential Revision: D28099628

fbshipit-source-id: c79658809210184d8895c3d1551e04b1baf88cae

folly/experimental/coro/GtestHelpers.h

@@ -172,4 +172,10 @@
 #define CO_ASSERT_GT(val1, val2) \
   CO_ASSERT_PRED_FORMAT2(::testing::internal::CmpHelperGT, val1, val2)
 
+/**
+ * coroutine version of FAIL() which is defined as GTEST_FAIL()
+ * GTEST_FATAL_FAILURE_("Failed")
+ */
+#define CO_FAIL() CO_GTEST_FATAL_FAILURE_("Failed")
+
 #endif // FOLLY_HAS_COROUTINES