tests: load plugins from build directory instead of installed libdir

This allows to run tests without running "make install".

tests/CMakeLists.txt

@@ -75,3 +75,5 @@ add_dependencies(tests
 add_test(NAME unit
   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
   COMMAND tests -v)
+set_property(TEST unit PROPERTY
+  ENVIRONMENT "WEECHAT_TESTS_ARGS=-p -r '/set weechat.plugin.path \"${PROJECT_BINARY_DIR}/src/plugins\"'")

tests/tests.cpp

@@ -160,6 +160,9 @@ main (int argc, char *argv[])
     /* display WeeChat version */
     input_data (gui_buffer_search_main (), "/command core version");
 
+    /* auto-load plugins, only from path in option weechat.plugin.path */
+    plugin_auto_load (0, NULL, 1, 0);
+
     /* run all tests */
     printf ("\n");
     printf (">>>>>>>>>> TESTS >>>>>>>>>>\n");