[BUILD] Fixing CMake to build GTest on Windows (#1887)

CMakeLists.txt

@@ -278,7 +278,12 @@ function(install_windows_deps)
     COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/tools/setup-buildtools.cmd)
   set(CMAKE_TOOLCHAIN_FILE
       ${CMAKE_CURRENT_SOURCE_DIR}/tools/vcpkg/scripts/buildsystems/vcpkg.cmake
-      PARENT_SCOPE)
+      CACHE FILEPATH "")
+  message(
+    "Make sure that vcpkg.cmake is set as the CMAKE_TOOLCHAIN_FILE at the START of the cmake build process!
+    Can be command-line arg (cmake -DCMAKE_TOOLCHAIN_FILE=...) or set in your editor of choice."
+  )
+
 endfunction()
 
 function(set_target_version target_name)
@@ -548,9 +553,10 @@ if(BUILD_TESTING)
         ${CMAKE_BINARY_DIR}/lib/libgmock.a)
   elseif(WIN32)
     # Make sure we are always bootsrapped with vcpkg on Windows
-    find_package(GTest REQUIRED)
+    find_package(GTest)
     if(NOT (GTEST_FOUND OR GTest_FOUND))
       install_windows_deps()
+      include(${CMAKE_TOOLCHAIN_FILE})
       find_package(GTest REQUIRED)
     endif()
   else()

test_common/src/http/client/nosend/CMakeLists.txt

@@ -28,7 +28,7 @@ if(${BUILD_TESTING})
   endif()
 
   target_link_libraries(
-    opentelemetry_http_client_nosend ${GTEST_BOTH_LIBRARIES} ${GMOCK_LIB}
-    opentelemetry_ext opentelemetry_test_common)
+    opentelemetry_http_client_nosend ${GTEST_BOTH_LIBRARIES} opentelemetry_ext
+    opentelemetry_test_common)
 
 endif()

tools/setup-buildtools.cmd

@@ -9,6 +9,7 @@ if defined VCPKG_ROOT (
   set "PATH=%VCPKG_ROOT%;%PATH%"
 ) else (
   set "PATH=%~dp0vcpkg;%PATH%"
+  set "VCPKG_ROOT=%~dp0vcpkg"
 )
 pushd %~dp0
 
@@ -53,9 +54,6 @@ where /Q vcpkg.exe
 if %ERRORLEVEL% == 1 (
   REM Build our own vcpkg from source
   REM Prefer building in VCPKG_ROOT
-  if not defined VCPKG_ROOT (
-    set "VCPKG_ROOT=%~dp0\vcpkg"
-  )
   pushd "!VCPKG_ROOT!"
   call bootstrap-vcpkg.bat
   popd