diff --git a/tests/20plugin.tests b/tests/20plugin.tests
deleted file mode 100644
index d1d9fba2f..000000000
--- a/tests/20plugin.tests
+++ /dev/null
@@ -1,24 +0,0 @@
-TESTING "test plugin example code" ./test-plugin
-
-PLANNED "C plugin example" C <<END
-out: opened
-out: Hallo Welt!
-out: Tschuess C
-out: opened
-out: Hello World!
-out: Bye C
-out: closed
-out: closed
-END
-
-PLANNED "C++ plugin example" C++ <<END
-out: opened
-out: Hallo Welt!
-out: Tschuess C++
-out: opened
-out: Hello World!
-out: Bye C++
-out: closed
-out: closed
-END
-
diff --git a/tests/31plugin.tests b/tests/31plugin.tests
new file mode 100644
index 000000000..d2107dd3c
--- /dev/null
+++ b/tests/31plugin.tests
@@ -0,0 +1,29 @@
+TESTING "testing plugins" ./test-interfaces
+
+
+TEST "discovering plugins, missing path" plugin_discover <<END
+out: error: LUMIERA_ERROR_CONFIG_NO_ENTRY:no configuration entry
+return: 0
+END
+
+export LUMIERA_PLUGIN_PATH=.libs
+
+TEST "discovering plugins" plugin_discover <<END
+out: found plugin: .libs/examplepluginc.so
+return: 0
+END
+
+TEST "plugin unloading" plugin_unload <<END
+out: plugin unload: (nil)
+return: 0
+END
+
+TEST "C plugin test" plugin_examplepluginc <<END
+out: Hallo Welt!
+out: Tschuess Welt!
+out: Hello World!
+out: Bye World!
+return: 0
+END
+
+unset LUMIERA_PLUGIN_PATH
diff --git a/tests/Makefile.am b/tests/Makefile.am
index a88377b92..12be3704d 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -26,42 +26,42 @@ test_error_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 check_PROGRAMS += test-locking
 test_locking_SOURCES = $(tests_srcdir)/library/test-locking.c
 test_locking_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror
-test_locking_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_locking_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_PROGRAMS += test-llist
 test_llist_SOURCES = $(tests_srcdir)/library/test-llist.c
 test_llist_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror
-test_llist_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_llist_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_PROGRAMS += test-psplay
 test_psplay_SOURCES = $(tests_srcdir)/library/test-psplay.c
 test_psplay_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror -I$(top_srcdir)/src/
-test_psplay_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_psplay_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_PROGRAMS += test-safeclib
 test_safeclib_SOURCES = $(tests_srcdir)/library/test-safeclib.c
 test_safeclib_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror
-test_safeclib_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_safeclib_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_PROGRAMS += test-luid
 test_luid_SOURCES = $(tests_srcdir)/library/test-luid.c
 test_luid_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror
-test_luid_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_luid_LDADD = liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_PROGRAMS += test-filedescriptors
 test_filedescriptors_SOURCES = $(tests_srcdir)/backend/test-filedescriptors.c
 test_filedescriptors_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror
-test_filedescriptors_LDADD = liblumibackend.a liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_filedescriptors_LDADD = liblumibackend.a liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_PROGRAMS += test-filehandles
 test_filehandles_SOURCES = $(tests_srcdir)/backend/test-filehandles.c
 test_filehandles_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror
-test_filehandles_LDADD = liblumibackend.a liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_filehandles_LDADD = liblumibackend.a liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_PROGRAMS += test-config
 test_config_SOURCES = $(tests_srcdir)/backend/test-config.c
 test_config_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror -I$(top_srcdir)/src/
-test_config_LDADD = liblumibackend.a liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_config_LDADD = liblumibackend.a liblumiera.a $(NOBUGMT_LUMIERA_LIBS)
 
 check_LTLIBRARIES += examplepluginc.la
 examplepluginc_la_SOURCES = $(tests_srcdir)/backend/example_plugin.c
@@ -71,7 +71,7 @@ examplepluginc_la_LDFLAGS = -module -avoid-version -no-undefined -rpath /dev/nul
 check_PROGRAMS += test-interfaces
 test_interfaces_SOURCES = $(tests_srcdir)/backend/test-interfaces.c
 test_interfaces_CPPFLAGS = $(AM_CPPFLAGS) -std=gnu99 -Wall -Werror
-test_interfaces_LDADD = liblumibackend.a liblumiera.a $(NOBUGMT_LUMIERA_LIBS) -lm
+test_interfaces_LDADD = liblumibackend.a liblumiera.a $(LUMIERA_PLUGIN_LIBS) $(NOBUGMT_LUMIERA_LIBS)
 test_interfaces_DEPENDENCIES = examplepluginc.la liblumibackend.a liblumiera.a
 
 TESTS = $(tests_srcdir)/test.sh
diff --git a/tests/backend/test-interfaces.c b/tests/backend/test-interfaces.c
index 110c6a855..f4355cc3b 100644
--- a/tests/backend/test-interfaces.c
+++ b/tests/backend/test-interfaces.c
@@ -22,7 +22,10 @@
 #include "backend/interface.h"
 #include "backend/interfaceregistry.h"
 #include "backend/interfacedescriptor.h"
+#include "backend/config.h"
+
 #include "tests/test.h"
+#include "tests/backend/hello_interface.h"
 
 /*
   define 2 example interfaces
@@ -452,11 +455,65 @@ TEST ("dependencies_all")
 }
 
 
-
-TEST ("highlevel, plugin")
+TEST ("plugin_discover")
 {
+  lumiera_config_init ("./");
+  lumiera_interfaceregistry_init ();
+
+  if (lumiera_plugin_discover (lumiera_plugin_load, lumiera_plugin_register))
+    {
+      LumieraPlugin p = lumiera_plugin_lookup (".libs/examplepluginc.so");
+      printf ("found plugin: %s\n", lumiera_plugin_name (p));
+      lumiera_plugin_discover (lumiera_plugin_load, lumiera_plugin_register);
+    }
+  else
+    printf ("error: %s\n", lumiera_error ());
+
+  lumiera_interfaceregistry_destroy ();
+  lumiera_config_destroy ();
+}
 
 
+TEST ("plugin_unload")
+{
+  lumiera_config_init ("./");
+  lumiera_interfaceregistry_init ();
+
+  lumiera_plugin_discover (lumiera_plugin_load, lumiera_plugin_register);
+  lumiera_plugin_unload (lumiera_plugin_lookup (".libs/examplepluginc.so"));
+  LumieraPlugin p = lumiera_plugin_lookup (".libs/examplepluginc.so");
+  printf ("plugin unload: %p\n", p);
+
+  lumiera_interfaceregistry_destroy ();
+  lumiera_config_destroy ();
+}
+
+
+TEST ("plugin_examplepluginc")
+{
+  lumiera_config_init ("./");
+  lumiera_interfaceregistry_init ();
+  lumiera_plugin_discover (lumiera_plugin_load, lumiera_plugin_register);
+
+  TODO ("macro to derrive minminor version from a slot");
+
+  LUMIERA_INTERFACE_HANDLE(lumieraorg_testhello, 0) german =
+    LUMIERA_INTERFACE_OPEN (lumieraorg_testhello, 0, 0, lumieraorg_hello_german);
+
+  LUMIERA_INTERFACE_HANDLE(lumieraorg_testhello, 0) english =
+    LUMIERA_INTERFACE_OPEN (lumieraorg_testhello, 0, 0, lumieraorg_hello_english);
+
+  german->hello ();
+  german->goodbye ("Welt!");
+
+  english->hello ();
+  english->goodbye ("World!");
+
+  LUMIERA_INTERFACE_CLOSE (german);
+  LUMIERA_INTERFACE_CLOSE (english);
+
+  lumiera_interfaceregistry_destroy ();
+  lumiera_config_destroy ();
 }
 
 TESTS_END