Precompile headers: Add unit tests

Tests/RunCMake/XcodeProject/RunCMakeTest.cmake

@@ -12,6 +12,7 @@ run_cmake(XcodeObjectNeedsQuote)
 run_cmake(XcodeOptimizationFlags)
 run_cmake(XcodePreserveNonOptimizationFlags)
 run_cmake(XcodePreserveObjcFlag)
+run_cmake(XcodePrecompileHeaders)
 if (NOT XCODE_VERSION VERSION_LESS 6)
   run_cmake(XcodePlatformFrameworks)
 endif()

Tests/RunCMake/XcodeProject/XcodePrecompileHeaders-check.cmake

@@ -0,0 +1,35 @@
+set(pch_header "${RunCMake_TEST_BINARY_DIR}/CMakeFiles/tgt.dir/cmake_pch.hxx")
+
+if(NOT EXISTS "${pch_header}")
+  set(RunCMake_TEST_FAILED "Generated PCH header ${pch_header} does not exist.")
+  return()
+endif()
+
+set(tgt_project "${RunCMake_TEST_BINARY_DIR}/XcodePrecompileHeaders.xcodeproj/project.pbxproj")
+if (NOT EXISTS "${tgt_project}")
+  set(RunCMake_TEST_FAILED "Generated project file ${tgt_project} doesn't exist.")
+  return()
+endif()
+
+file(STRINGS ${tgt_project} tgt_projects_strings)
+
+foreach(line IN LISTS tgt_projects_strings)
+  if (line MATCHES "GCC_PRECOMPILE_PREFIX_HEADER = YES;")
+    set(have_pch_prefix ON)
+  endif()
+
+  string(FIND "${line}" "GCC_PREFIX_HEADER = \"${pch_header}\";" find_pos)
+  if (NOT find_pos EQUAL "-1")
+    set(have_pch_header ON)
+  endif()
+endforeach()
+
+if (NOT have_pch_prefix)
+  set(RunCMake_TEST_FAILED "Generated project should have the GCC_PRECOMPILE_PREFIX_HEADER = YES; line.")
+  return()
+endif()
+
+if (NOT have_pch_header)
+  set(RunCMake_TEST_FAILED "Generated project should have the GCC_PREFIX_HEADER = \"${pch_header}\"; line.")
+  return()
+endif()

Tests/RunCMake/XcodeProject/XcodePrecompileHeaders.cmake

@@ -0,0 +1,4 @@
+project(XcodePrecompileHeaders CXX)
+
+add_library(tgt foo.cpp)
+target_precompile_headers(tgt PRIVATE stdafx.h)