https://github.com/Tencent/rapidjson/issues/1808

--- a/test/unittest/CMakeLists.txt
+++ b/test/unittest/CMakeLists.txt
@@ -77,12 +77,15 @@
     COMMAND ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/unittest
     WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}/bin)
 
-if(NOT MSVC)
+find_program(VALGRIND_EXECUTABLE valgrind)
+if(VALGRIND_EXECUTABLE)
     # Not running SIMD.* unit test cases for Valgrind
     add_test(NAME valgrind_unittest
         COMMAND valgrind --leak-check=full --error-exitcode=1 ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/unittest --gtest_filter=-SIMD.*
         WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}/bin)
+endif(VALGRIND_EXECUTABLE)
 
+if(NOT MSVC)
     if(CMAKE_BUILD_TYPE STREQUAL "Debug")
         add_test(NAME symbol_check
         COMMAND sh -c "objdump -t -C libnamespacetest.a | grep rapidjson ; test $? -ne 0"