Many times unit tests for different libraries would like to use
the same helper functions for checking common types of errors.
This patch adds a common library with helpers for testing things
in Support, and introduces helpers in here for integrating the
llvm::Error and llvm::Expected<T> classes with gtest and gmock.
Normally, we would just be able to write:
EXPECT_THAT(someFunction(), succeeded());
but due to some quirks in llvm::Error's move semantics, gmock
doesn't make this easy, so two macros EXPECT_THAT_ERROR() and
EXPECT_THAT_EXPECTED() are introduced to gloss over the difficulties.
Consider this an exception, and possibly only temporary as we
look for ways to improve this.
Differential Revision: https://reviews.llvm.org/D33059
llvm-svn: 305395