Tests: Add RunCMake.CPackCommandLine case for multi-config package

In commit da5ac4bb60 (cpack: Add `CPACK_INSTALL_CMAKE_CONFIGURATIONS`
variable, 2019-07-10, v3.16.0-rc1~165^2) we added support for running
the `cpack -C ...` command-line with multiple configurations.  Add an
explicit test for this.

Fixes: #19918

Tests/RunCMake/CPackCommandLine/CMakeLists.txt

@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.16)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)

Tests/RunCMake/CPackCommandLine/MultiConfig-check-stdout.txt

@@ -0,0 +1,4 @@
+MultiConfig-0\.1\.1-[^/
+]*/lib/(lib|)foo_dbg\.(a|lib)
+MultiConfig-0\.1\.1-[^/
+]*/lib/(lib|)foo_rel\.(a|lib)

Tests/RunCMake/CPackCommandLine/MultiConfig-package-stdout.txt

@@ -0,0 +1,8 @@
+^CPack: Create package using ZIP
+CPack: Install projects
+CPack: - Install project: MultiConfig \[Debug\]
+CPack: - Install project: MultiConfig \[Release\]
+CPack: Create package
+CPack: - package: [^
+]*/Tests/RunCMake/CPackCommandLine/MultiConfig-build/MultiConfig-0.1.1-[^
+]*.zip generated.$

Tests/RunCMake/CPackCommandLine/MultiConfig.cmake

@@ -0,0 +1,9 @@
+enable_language(C)
+
+include(CPack)
+
+add_library(foo foo.c)
+set_property(TARGET foo PROPERTY DEBUG_POSTFIX _dbg)
+set_property(TARGET foo PROPERTY RELEASE_POSTFIX _rel)
+
+install(TARGETS foo)

Tests/RunCMake/CPackCommandLine/RunCMakeTest.cmake

@@ -8,3 +8,26 @@ set(CPACK_PACKAGE_VERSION "1")
 set(RunCMake_TEST_NO_CLEAN 1)
 run_cmake_command(NotAGenerator ${CMAKE_CPACK_COMMAND} -G NotAGenerator)
 unset(RunCMake_TEST_NO_CLEAN)
+
+function(run_MultiConfig)
+  set(RunCMake_TEST_BINARY_DIR "${RunCMake_BINARY_DIR}/MultiConfig-build")
+  run_cmake(MultiConfig)
+  set(RunCMake_TEST_NO_CLEAN 1)
+  run_cmake_command(MultiConfig-build-dbg ${CMAKE_COMMAND} --build . --config Debug)
+  run_cmake_command(MultiConfig-build-rel ${CMAKE_COMMAND} --build . --config Release)
+  run_cmake_command(MultiConfig-package ${CMAKE_CPACK_COMMAND} -G ZIP -C "Debug\;Release")
+  set(zip_glob "${RunCMake_TEST_BINARY_DIR}/MultiConfig-0.1.1-*.zip")
+  file(GLOB zips "${zip_glob}")
+  set(zip_found 0)
+  foreach(zip IN LISTS zips)
+    set(zip_found 1)
+    run_cmake_command(MultiConfig-check ${CMAKE_COMMAND} -E tar tf "${zip}")
+  endforeach()
+  if(NOT zip_found)
+    message(SEND_ERROR "No package file found at\n ${zip_glob}")
+  endif()
+endfunction()
+
+if(RunCMake_GENERATOR MATCHES "Visual Studio|Xcode")
+  run_MultiConfig()
+endif()

Tests/RunCMake/CPackCommandLine/foo.c

@@ -0,0 +1,4 @@
+int foo(void)
+{
+  return 0;
+}