Add hmac_drbg_{write,update}_seed_file()
diff --git a/tests/suites/test_suite_hmac_drbg.function b/tests/suites/test_suite_hmac_drbg.function
index a95beb2..09e55b7 100644
--- a/tests/suites/test_suite_hmac_drbg.function
+++ b/tests/suites/test_suite_hmac_drbg.function
@@ -28,6 +28,23 @@
  * END_DEPENDENCIES
  */
 
+/* BEGIN_CASE depends_on:POLARSSL_FS_IO */
+void hmac_drbg_seed_file( int md_alg, char *path, int ret )
+{
+    const md_info_t *md_info;
+    hmac_drbg_context ctx;
+
+    TEST_ASSERT( ( md_info = md_info_from_type( md_alg ) ) != NULL );
+    TEST_ASSERT( hmac_drbg_init( &ctx, md_info, rnd_std_rand, NULL,
+                                 NULL, 0 ) == 0 );
+
+    TEST_ASSERT( hmac_drbg_write_seed_file( &ctx, path ) == ret );
+    TEST_ASSERT( hmac_drbg_update_seed_file( &ctx, path ) == ret );
+
+    hmac_drbg_free( &ctx );
+}
+/* END_CASE */
+
 /* BEGIN_CASE */
 void hmac_drbg_no_reseed( int md_alg,
                           char *entropy_hex, char *custom_hex,