Add example for the weak linking

examples/weak_linking/test/display.test.c

@@ -0,0 +1,27 @@
+
+#include "test_common.h"
+
+#include "display.h"
+
+DEFINE_FFF_GLOBALS;
+
+
+int main(void)
+{
+   init_tests(); // will reset common and hook errors to asserts
+   
+   GLOBAL_TEST_bus_read_ret[2] = 0x10;
+   assert( display_init() == true );
+   assert( bus_read_write_fake.call_count == 1);
+   
+   display_update( "TEST INFO" );
+   assert( bus_read_write_fake.call_count == 1 );
+   assert( bus_write_fake.call_count == 1 );
+
+   GLOBAL_TEST_bus_read_ret[2] = 0x00;
+   assert( display_init() == false );
+   
+   printf("Test " __FILE__ " ok\n");
+   return 0;
+
+}