diff -r e0f850709a5c -r e18884bbad48 test/utils_tests.c
--- a/test/utils_tests.c	Wed Sep 07 12:26:01 2016 +0200
+++ b/test/utils_tests.c	Wed Sep 07 12:41:30 2016 +0200
@@ -91,6 +91,47 @@
     free(teststr2);
 }
 
+UCX_TEST(test_ucx_sprintf) {
+    UCX_TEST_BEGIN
+    
+    sstr_t s1 = ucx_sprintf("int: %d\nHello %s!", 123, "World");
+    UCX_TEST_ASSERT(s1.ptr, "s1.ptr is NULL");
+    UCX_TEST_ASSERT(s1.length == 21, "wrong length");
+    UCX_TEST_ASSERT(!sstrcmp(s1, S("int: 123\nHello World!")), "wrong content");
+    free(s1.ptr);
+    
+    sstr_t s2 = ucx_sprintf("Nothing to format!");
+    UCX_TEST_ASSERT(s2.ptr, "s2.ptr is NULL");
+    UCX_TEST_ASSERT(s2.length == 18, "wrong length");
+    UCX_TEST_ASSERT(!memcmp(s2.ptr, "Nothing to format!", 18),
+            "wrong string without format arguments");
+    free(s2.ptr);
+    
+    UCX_TEST_END
+}
+
+UCX_TEST(test_ucx_bprintf) {
+    UcxBuffer *b = ucx_buffer_new(NULL, 64, UCX_BUFFER_DEFAULT);
+    
+    UCX_TEST_BEGIN
+    
+    ucx_bprintf(b, "int: %d\nHello %s!", 123, "World");
+    UCX_TEST_ASSERT(b->size == 21, "wrong length");
+    UCX_TEST_ASSERT(!memcmp(b->space, "int: 123\nHello World!", 21),
+            "wrong content");
+            
+    ucx_buffer_clear(b);
+            
+    ucx_bprintf(b, "Nothing to format!");
+    UCX_TEST_ASSERT(b->size == 18, "wrong length");
+    UCX_TEST_ASSERT(!memcmp(b->space, "Nothing to format!", 18),
+            "wrong string without format arguments");
+            
+    UCX_TEST_END
+    
+    ucx_buffer_free(b);
+}
+
 UCX_TEST(test_ucx_stream_copy) {
     UcxBuffer *b1 = ucx_buffer_new(NULL, 64, UCX_BUFFER_DEFAULT);
     UcxBuffer *b2 = ucx_buffer_new(NULL, 2, UCX_BUFFER_AUTOEXTEND);
@@ -143,3 +184,4 @@
     ucx_buffer_free(b1);
     ucx_buffer_free(b2);
 }
+