help for problem in g_cache_insert() example code?

[Biswajeet Dash <biswajeet dash gmail com>]

#undef G_DISABLE_ASSERT
#undef G_LOG_DOMAIN

#include <stdio.h>
#include <string.h>
#include "glib.h"

void function(gchar *key,gchar *value,gint *user_data)
{
 // give the count of the number of times the function was called

 (*user_data)++;
}

void cache_test()
{
 gchar *str1,*str2,*str3;
 GCache *cache = NULL;
 gint user_data = 0;

 g_assert((cache = g_cache_new( (GCacheNewFunc) g_ascii_strup,
     g_free, (GCacheDupFunc) g_strdup, g_free, g_str_hash,
       g_str_hash, g_str_equal)) != NULL);
     str1 = g_cache_insert(cache,"test");
        g_assert(!strcmp("TEST",str1));
   str2 = g_cache_insert(cache,"test");
g_assert(!strcmp("TEST",str1));
 str3 = g_cache_insert(cache,"glib");
 g_assert(!strcmp("GLIB",str3));
 g_cache_key_foreach (cache,(GHFunc)function,&user_data);
 //g_cache_key_foreach would call function twice and make user_data == 2
 g_assert(user_data == 2);
 g_cache_value_foreach (cache,(GHFunc)function,&user_data);
 //g_cache_value_foreach would call function twice and make user_data == 4
 g_assert(user_data == 4);
 g_cache_remove(cache,str1);
 g_cache_remove(cache,str2); 
 g_cache_remove(cache,str3); 
 g_cache_destroy(cache);
}


int main (int   argc,
      char *argv[])
{
 cache_test();
 return 0;

}

Now my test example crashes at str1 = g_cache_insert(cache,"test"); because of null pointer dereferencing.

Any help where i could be going wrong?

Regards

Biswajeet