- Fixed a whole bunch of dependencies on defines between files, examples and tests

diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index 905f1c3..1b328c4 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -1,16 +1,11 @@
 BEGIN_HEADER
 #include <polarssl/bignum.h>
-
-static int myrand( void *rng_state )
-{
-    if( rng_state != NULL )
-        rng_state  = NULL;
-
-    return( rand() );
-}
-
 END_HEADER
 
+BEGIN_DEPENDENCIES
+depends_on:POLARSSL_BIGNUM_C
+END_DEPENDENCIES
+
 BEGIN_CASE
 mpi_read_write_string:radix_X:input_X:radix_A:input_A:output_size:result_read:result_write
 {
@@ -129,10 +124,12 @@
     TEST_ASSERT( mpi_read_string( &X, {radix_X}, {input_X} ) == 0 );
 
     file_out = fopen( {output_file}, "w" );
+    TEST_ASSERT( file_out != NULL );
     TEST_ASSERT( mpi_write_file( NULL, &X, {output_radix}, file_out ) == 0 );
     fclose(file_out);
 
     file_in = fopen( {output_file}, "r" );
+    TEST_ASSERT( file_in != NULL );
     TEST_ASSERT( mpi_read_file( &Y, {output_radix}, file_in ) == 0 );
     fclose(file_in);
 
@@ -612,7 +609,7 @@
     mpi_init( &X );
 
     TEST_ASSERT( mpi_read_string( &X, {radix_X}, {input_X} ) == 0 );
-    res = mpi_is_prime( &X, myrand, NULL );
+    res = mpi_is_prime( &X, rnd_std_rand, NULL );
     TEST_ASSERT( res == {div_result} );
 
     mpi_free( &X );