Add example g_add_test

Now it should be easier to start adding tests

tests/test.c

@@ -1,11 +1,30 @@
 #include <glib.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
+
+typedef struct {
+  int a; /* usually some other data structure that you
+          * need for your tests */
+} dfixture;
+
+void my_setup(dfixture *df, gconstpointer test_data) {
+  /* here goes the code to setup fixture */
+}
+
+void my_teardown(dfixture *df, gconstpointer test_data) {
+  /* here goes the code to free/cleanup fixture */
+}
+
+void my_first_test(dfixture *df, gconstpointer ignored) {
+  /* g_assert(false); */
+  g_assert(true);
+}
 
 int main(int argc, char *argv[])
 {
+  /* https://developer.gnome.org/glib/stable/glib-Testing.html */
   g_test_init(&argc, &argv, NULL);
-  printf("Write some tests!!! Failing!\n");
-  exit(EXIT_FAILURE);
-  return 0;
+  g_test_add("/set0/my first test", /* type fixture*/ dfixture, /*tdata*/NULL, /*fsetup*/ my_setup, my_first_test, my_teardown);
+  return g_test_run();
 }