Merge pull request #11486 from ladislas/update-googletest

update googletest to v1.8.1

UNITTESTS/CMakeLists.txt

@@ -52,8 +52,8 @@ add_subdirectory(${CMAKE_BINARY_DIR}/googletest-src
 # dependencies automatically when using CMake 2.8.11 or
 # later.
 target_include_directories(gmock_main SYSTEM BEFORE INTERFACE
-  "${gtest_SOURCE_DIR}/include"
-  "${gmock_SOURCE_DIR}/include")
+  "$<BUILD_INTERFACE:${gtest_SOURCE_DIR}/include>"
+  "$<BUILD_INTERFACE:${gmock_SOURCE_DIR}/include>")
 
 ####################
 # TESTING

UNITTESTS/README.md

@@ -85,6 +85,8 @@ Mbed CLI supports unit tests through the `mbed test --unittests` command. For in
 
 A unit tests suite consists of one or more test cases. The test cases should cover all the functions in a class under test. All the external dependencies are stubbed including the other classes in the same module. Avoid stubbing header files. Finally, analyze code coverage to ensure all code is tested, and no dead code is found.
 
+Unit tests are written using [Google Test v1.8.1](https://github.com/google/googletest/releases/tag/release-1.8.1).
+
 Please see the [documentation for Google Test](https://github.com/google/googletest/blob/master/googletest/docs/primer.md) to learn how to write unit tests using its framework. See the [documentation for Google Mock](https://github.com/google/googletest/blob/master/googlemock/docs/Documentation.md) if you want to write and use C++ mock classes instead of stubs.
 
 #### Test suite configuration

UNITTESTS/googletest-CMakeLists.txt.in

@@ -5,7 +5,7 @@ project(googletest-download NONE)
 include(ExternalProject)
 ExternalProject_Add(googletest
   GIT_REPOSITORY    https://github.com/google/googletest.git
-  GIT_TAG           8bc11c040a1dcbe50c340b21d78175d152dd3837
+  GIT_TAG           release-1.8.1
   SOURCE_DIR        "${CMAKE_BINARY_DIR}/googletest-src"
   BINARY_DIR        "${CMAKE_BINARY_DIR}/googletest-build"
   CONFIGURE_COMMAND ""