Make test suite optional by using CTest

CMakeLists.txt

@@ -15,6 +15,9 @@ option(ENABLE_HLSL "Enables HLSL input support" ON)
 
 project(glslang)
 
+# make testing optional
+include(CTest)
+
 if(ENABLE_AMD_EXTENSIONS)
     add_definitions(-DAMD_EXTENSIONS)
 endif(ENABLE_AMD_EXTENSIONS)

External/CMakeLists.txt

@@ -1,6 +1,7 @@
 # Suppress all warnings from external projects.
 set_property(DIRECTORY APPEND PROPERTY COMPILE_OPTIONS -w)
 
+if(BUILD_TESTING)
     if(TARGET gmock)
         message(STATUS "Google Mock already configured - use it")
     elseif(IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/googletest)
@@ -31,3 +32,4 @@ else()
         message(STATUS
             "Google Mock was not found - tests based on that will not build")
     endif()
+endif()

gtests/CMakeLists.txt

@@ -1,3 +1,4 @@
+if(BUILD_TESTING)
     if(TARGET gmock)
         message(STATUS "Google Mock found - building tests")
 
@@ -53,3 +54,4 @@ if (TARGET gmock)
         add_test(NAME glslang-gtests
                  COMMAND glslangtests --test-root "${GLSLANG_TEST_DIRECTORY}")
     endif()
+endif()