Fix windows tests

Signed-off-by: Addisu Z. Taddese <addisu@openrobotics.org>

core/src/cmd/CMakeLists.txt

@@ -31,7 +31,13 @@ set(cmd_script_configured "${CMAKE_CURRENT_BINARY_DIR}/cmd${GZ_DESIGNATION}${PRO
 
 # Set the library_location variable to the relative path to the library file
 # within the install directory structure.
-set(library_location "../../../${CMAKE_INSTALL_LIBDIR}/$<TARGET_FILE_NAME:${PROJECT_LIBRARY_TARGET_NAME}>")
+if (MSVC)
+  set(library_location_prefix "${CMAKE_INSTALL_BINDIR}")
+else()
+  set(library_location_prefix "${CMAKE_INSTALL_LIBDIR}")
+endif()
+
+set(library_location "../../../${library_location_prefix}/$<TARGET_FILE_NAME:${PROJECT_NAME}>")
 
 configure_file(
   "cmd${GZ_DESIGNATION}.rb.in"

core/src/cmd/cmdmsgs.rb.in

@@ -26,6 +26,7 @@ else
 end
 
 require 'optparse'
+require 'pathname'
 
 # Constants.
 LIBRARY_NAME = '@library_location@'
@@ -101,7 +102,7 @@ class Cmd
     # puts options
 
     # Read the plugin that handles the command.
-    if LIBRARY_NAME[0] == '/'
+    if Pathname.new(LIBRARY_NAME).absolute?
       # If the first character is a slash, we'll assume that we've been given an
       # absolute path to the library. This is only used during test mode.
       plugin = LIBRARY_NAME
@@ -112,6 +113,13 @@ class Cmd
     end
     conf_version = LIBRARY_VERSION
 
+    if defined? RubyInstaller
+      # RubyInstaller does not search for dlls in PATH or the directory that tests are running from,
+      # so we'll add the parent directory of the plugin to the search path.
+      # https://github.com/oneclick/rubyinstaller2/wiki/For-gem-developers#-dll-loading
+      RubyInstaller::Runtime.add_dll_directory(File.dirname(plugin))
+    end
+
     begin
       Importer.dlload plugin
     rescue DLError