Tests: Add case covering FindPkgConfig creation of empty targets

Tests/RunCMake/FindPkgConfig/FindPkgConfig_empty_target.cmake

@@ -0,0 +1,13 @@
+# Prepare environment to reuse empty.pc
+file(TO_NATIVE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/pc-empty/lib/pkgconfig" PC_PATH)
+if(UNIX)
+  string(REPLACE "\\ " " " PC_PATH "${PC_PATH}")
+endif()
+set(ENV{PKG_CONFIG_PATH} "${PC_PATH}")
+
+find_package(PkgConfig REQUIRED)
+pkg_search_module(Empty REQUIRED empty IMPORTED_TARGET)
+
+if(NOT Empty_MODULE_NAME STREQUAL "empty")
+  message(FATAL_ERROR "Wrong value for Empty_MODULE_NAME. Expected: empty, got: ${Empty_MODULE_NAME}")
+endif()

Tests/RunCMake/FindPkgConfig/RunCMakeTest.cmake

@@ -29,4 +29,5 @@ if (PKG_CONFIG_FOUND)
   run_cmake(FindPkgConfig_IMPORTED_TARGET)
   run_cmake(FindPkgConfig_VERSION_OPERATORS)
   run_cmake(FindPkgConfig_GET_MATCHING_MODULE_NAME)
+  run_cmake(FindPkgConfig_empty_target)
 endif ()

Tests/RunCMake/FindPkgConfig/pc-empty/lib/pkgconfig/empty.pc

@@ -0,0 +1,5 @@
+Name: Empty
+Description: Dummy package to test empty target
+Version: 1.0
+Libs:
+Cflags: