FindPkgConfig: Make IMPORTED_TARGET test verify NO...PATH properly

Tests/RunCMake/FindPkgConfig/FindPkgConfig_IMPORTED_TARGET.cmake

@@ -24,3 +24,64 @@ if (NCURSES_FOUND)
 else ()
   message(STATUS "skipping test; ncurses not found")
 endif ()
+
+
+# Setup for the remaining package tests below
+set(PKG_CONFIG_USE_CMAKE_PREFIX_PATH)
+set(fakePkgDir ${CMAKE_CURRENT_BINARY_DIR}/pc-fakepackage)
+foreach(i 1 2)
+  set(pname cmakeinternalfakepackage${i})
+  file(WRITE ${fakePkgDir}/lib/lib${pname}.a "")
+  file(WRITE ${fakePkgDir}/lib/${pname}.lib  "")
+  file(WRITE ${fakePkgDir}/lib/pkgconfig/${pname}.pc
+"Name: CMakeInternalFakePackage${i}
+Description: Dummy package (${i}) for FindPkgConfig IMPORTED_TARGET test
+Version: 1.2.3
+Libs: -l${pname}
+")
+endforeach()
+
+# Always find the .pc file in the calls further below so that we can test that
+# the import target find_library() calls handle the NO...PATH options correctly
+set(ENV{PKG_CONFIG_PATH} ${fakePkgDir}/lib/pkgconfig)
+
+# Confirm correct behavior of NO_CMAKE_PATH, ensuring we only find the library
+# for the imported target if we have both set CMAKE_PREFIX_PATH and have not
+# given the NO_CMAKE_PATH option
+unset(CMAKE_PREFIX_PATH)
+unset(ENV{CMAKE_PREFIX_PATH})
+pkg_check_modules(FakePackage1 QUIET IMPORTED_TARGET cmakeinternalfakepackage1)
+if (TARGET PkgConfig::FakePackage1)
+  message(FATAL_ERROR "Have import target for fake package 1 with no path prefix")
+endif()
+
+set(CMAKE_PREFIX_PATH ${fakePkgDir})
+pkg_check_modules(FakePackage1 QUIET IMPORTED_TARGET NO_CMAKE_PATH cmakeinternalfakepackage1)
+if (TARGET PkgConfig::FakePackage1)
+  message(FATAL_ERROR "Have import target for fake package 1 with ignored cmake path")
+endif()
+
+pkg_check_modules(FakePackage1 REQUIRED QUIET IMPORTED_TARGET cmakeinternalfakepackage1)
+if (NOT TARGET PkgConfig::FakePackage1)
+  message(FATAL_ERROR "No import target for fake package 1 with prefix path")
+endif()
+
+# And now do the same for the NO_CMAKE_ENVIRONMENT_PATH - ENV{CMAKE_PREFIX_PATH}
+# combination
+unset(CMAKE_PREFIX_PATH)
+unset(ENV{CMAKE_PREFIX_PATH})
+pkg_check_modules(FakePackage2 QUIET IMPORTED_TARGET cmakeinternalfakepackage2)
+if (TARGET PkgConfig::FakePackage2)
+  message(FATAL_ERROR "Have import target for fake package 2 with no path prefix")
+endif()
+
+set(ENV{CMAKE_PREFIX_PATH} ${fakePkgDir})
+pkg_check_modules(FakePackage2 QUIET IMPORTED_TARGET NO_CMAKE_ENVIRONMENT_PATH cmakeinternalfakepackage2)
+if (TARGET PkgConfig::FakePackage2)
+  message(FATAL_ERROR "Have import target for fake package 2 with ignored cmake path")
+endif()
+
+pkg_check_modules(FakePackage2 REQUIRED QUIET IMPORTED_TARGET cmakeinternalfakepackage2)
+if (NOT TARGET PkgConfig::FakePackage2)
+  message(FATAL_ERROR "No import target for fake package 2 with prefix path")
+endif()