diff --git a/tests/suites/test_suite_asn1write.data b/tests/suites/test_suite_asn1write.data
index f98df4e..90654d7 100644
--- a/tests/suites/test_suite_asn1write.data
+++ b/tests/suites/test_suite_asn1write.data
@@ -82,56 +82,62 @@
 ASN.1 Write mpi, 256*8-1 bits
 mbedtls_asn1_write_mpi:"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":"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"
 
-ASN.1 Write Octet String #0 (Empty string)
-mbedtls_asn1_write_octet_string:"":"0400":2:2
+ASN.1 Write OCTET STRING: length=0
+mbedtls_asn1_write_string:MBEDTLS_ASN1_OCTET_STRING:"":"0400"
 
-ASN.1 Write Octet String #1 (Large buffer)
-mbedtls_asn1_write_octet_string:"AABBCC":"0403AABBCC":10:5
+ASN.1 Write OCTET STRING: length=1
+mbedtls_asn1_write_string:MBEDTLS_ASN1_OCTET_STRING:"41":"040141"
 
-ASN.1 Write Octet String #2 (Buffer just fits)
-mbedtls_asn1_write_octet_string:"AABBCC":"0403AABBCC":5:5
+ASN.1 Write OCTET STRING: length=2
+mbedtls_asn1_write_string:MBEDTLS_ASN1_OCTET_STRING:"4142":"04024142"
 
-ASN.1 Write Octet String #3 (Buffer too small for tag)
-mbedtls_asn1_write_octet_string:"AABBCC":"0403AABBCC":4:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write OCTET STRING: length=127
+mbedtls_asn1_write_string:MBEDTLS_ASN1_OCTET_STRING:"99a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38":"047f99a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38"
 
-ASN.1 Write Octet String #4 (Buffer too small for len)
-mbedtls_asn1_write_octet_string:"AABBCC":"0403AABBCC":3:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write OCTET STRING: length=128
+mbedtls_asn1_write_string:MBEDTLS_ASN1_OCTET_STRING:"0199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38":"0481800199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38"
 
-ASN.1 Write Octet String #5 (Buffer too small for string)
-mbedtls_asn1_write_octet_string:"AABBCC":"0403AABBCC":2:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write OCTET STRING: length=255
+mbedtls_asn1_write_string:MBEDTLS_ASN1_OCTET_STRING:"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":"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"
 
-ASN.1 Write Octet String #6 (l = 128, large buffer)
-mbedtls_asn1_write_octet_string:"000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F":"048180000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F":140:131
+ASN.1 Write OCTET STRING: length=256
+mbedtls_asn1_write_string:MBEDTLS_ASN1_OCTET_STRING:"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":"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"
 
-ASN.1 Write Octet String #7 (l = 128, buffer just fits)
-mbedtls_asn1_write_octet_string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
+ASN.1 Write UTF8 STRING: length=0
+mbedtls_asn1_write_string:MBEDTLS_ASN1_UTF8_STRING:"":"0c00"
 
-ASN.1 Write Octet String #8 (l = 128, buffer too small for tag)
-mbedtls_asn1_write_octet_string:"000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F":"":130:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write UTF8 STRING: length=1
+mbedtls_asn1_write_string:MBEDTLS_ASN1_UTF8_STRING:"41":"0c0141"
 
-ASN.1 Write Octet String #9 (l = 128, buffer too small for len)
-mbedtls_asn1_write_octet_string:"000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F":"":129:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write UTF8 STRING: length=128
+mbedtls_asn1_write_string:MBEDTLS_ASN1_UTF8_STRING:"0199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38":"0c81800199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38"
 
-ASN.1 Write Octet String #9 (l = 128, buffer too small for string)
-mbedtls_asn1_write_octet_string:"000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F":"":127:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write PRINTABLE STRING: length=0
+mbedtls_asn1_write_string:MBEDTLS_ASN1_PRINTABLE_STRING:"":"1300"
 
-ASN.1 Write IA5 String #0 (Empty string)
-mbedtls_asn1_write_ia5_string:"":"1600":2:2
+ASN.1 Write PRINTABLE STRING: length=1
+mbedtls_asn1_write_string:MBEDTLS_ASN1_PRINTABLE_STRING:"41":"130141"
 
-ASN.1 Write IA5 String #1 (Large buffer)
-mbedtls_asn1_write_ia5_string:"ABC":"1603414243":10:5
+ASN.1 Write PRINTABLE STRING: length=128
+mbedtls_asn1_write_string:MBEDTLS_ASN1_PRINTABLE_STRING:"0199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38":"1381800199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38"
 
-ASN.1 Write IA5 String #2 (Buffer just fits)
-mbedtls_asn1_write_ia5_string:"ABC":"1603414243":5:5
+ASN.1 Write IA5 STRING: length=0
+mbedtls_asn1_write_string:MBEDTLS_ASN1_IA5_STRING:"":"1600"
 
-ASN.1 Write IA5 String #3 (Buffer too small for tag)
-mbedtls_asn1_write_ia5_string:"ABC":"":4:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write IA5 STRING: length=1
+mbedtls_asn1_write_string:MBEDTLS_ASN1_IA5_STRING:"41":"160141"
 
-ASN.1 Write IA5 String #4 (Buffer too small for len)
-mbedtls_asn1_write_ia5_string:"ABC":"":3:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write IA5 STRING: length=128
+mbedtls_asn1_write_string:MBEDTLS_ASN1_IA5_STRING:"0199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38":"1681800199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38"
 
-ASN.1 Write IA5 String #5 (Buffer too small for string)
-mbedtls_asn1_write_ia5_string:"ABC":"":2:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
+ASN.1 Write tagged string: length=0
+mbedtls_asn1_write_string:MBEDTLS_ASN1_IA5_STRING | MBEDTLS_ASN1_CONTEXT_SPECIFIC:"":"9600"
+
+ASN.1 Write tagged string: length=1
+mbedtls_asn1_write_string:MBEDTLS_ASN1_IA5_STRING | MBEDTLS_ASN1_CONTEXT_SPECIFIC:"41":"960141"
+
+ASN.1 Write tagged string: length=128
+mbedtls_asn1_write_string:MBEDTLS_ASN1_IA5_STRING | MBEDTLS_ASN1_CONTEXT_SPECIFIC:"0199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38":"9681800199a66790856f7199641f55cadabb660aaed6aa0d9ef8cef4417118c6e8c6e15becbaa21c63faf48726e92357a38b3079a0b9d60be7457ec6552f900dd032577167c91e829927343c3a769b362db4de0ad2ffb8f13cc2eeca9e52dc557118baa88b857477595622bc301a1ae2150030d652c4a482cf88d0ded85d6731ff2d38"
 
 ASN.1 Write / Read Length #0 (Len = 0, short form)
 mbedtls_asn1_write_len:0:"00":1:1
@@ -176,73 +182,73 @@
 mbedtls_asn1_write_len:16909060:"8401020304":4:MBEDTLS_ERR_ASN1_BUF_TOO_SMALL
 
 ASN.1 Write Named Bitstring / Unused bits #0
-test_asn1_write_bitstrings:"FF":8:"030200FF":4:1
+test_asn1_write_bitstrings:"FF":8:"030200FF":1
 
 ASN.1 Write Named Bitstring / Unused bits #1
-test_asn1_write_bitstrings:"FE":8:"030201FE":4:1
+test_asn1_write_bitstrings:"FE":8:"030201FE":1
 
 ASN.1 Write Named Bitstring / Unused bits #2
-test_asn1_write_bitstrings:"FC":7:"030202FC":4:1
+test_asn1_write_bitstrings:"FC":7:"030202FC":1
 
 ASN.1 Write Named Bitstring / Unused bits #3
-test_asn1_write_bitstrings:"F8":8:"030203F8":4:1
+test_asn1_write_bitstrings:"F8":8:"030203F8":1
 
 ASN.1 Write Named Bitstring / Unused bits #4
-test_asn1_write_bitstrings:"F0":6:"030204F0":4:1
+test_asn1_write_bitstrings:"F0":6:"030204F0":1
 
 ASN.1 Write Named Bitstring / Unused bits #5
-test_asn1_write_bitstrings:"E0":6:"030205E0":4:1
+test_asn1_write_bitstrings:"E0":6:"030205E0":1
 
 ASN.1 Write Named Bitstring / Unused bits #6
-test_asn1_write_bitstrings:"C0":8:"030206C0":4:1
+test_asn1_write_bitstrings:"C0":8:"030206C0":1
 
 ASN.1 Write Named Bitstring / Unused bits #7
-test_asn1_write_bitstrings:"80":8:"03020780":4:1
+test_asn1_write_bitstrings:"80":8:"03020780":1
 
 ASN.1 Write Named Bitstring / Empty bitstring
-test_asn1_write_bitstrings:"00":7:"030100":3:1
+test_asn1_write_bitstrings:"00":7:"030100":1
 
 ASN.1 Write Named Bitstring / Empty bitstring (bits = 16)
-test_asn1_write_bitstrings:"0000":16:"030100":3:1
+test_asn1_write_bitstrings:"0000":16:"030100":1
 
 ASN.1 Write Named Bitstring / Empty bitstring (bits = 24)
-test_asn1_write_bitstrings:"FFFFFF":0:"030100":3:1
+test_asn1_write_bitstrings:"FFFFFF":0:"030100":1
 
 ASN.1 Write Named Bitstring / 15 trailing bits all unset
-test_asn1_write_bitstrings:"F88000":24:"030307F880":5:1
+test_asn1_write_bitstrings:"F88000":24:"030307F880":1
 
 ASN.1 Write Named Bitstring / 15 trailing bits all set
-test_asn1_write_bitstrings:"F8FFFF":9:"030307F880":5:1
+test_asn1_write_bitstrings:"F8FFFF":9:"030307F880":1
 
 ASN.1 Write Bitstring / Unused bits #0
-test_asn1_write_bitstrings:"FF":8:"030200FF":4:0
+test_asn1_write_bitstrings:"FF":8:"030200FF":0
 
 ASN.1 Write Bitstring / Unused bits #1
-test_asn1_write_bitstrings:"FF":7:"030201FE":4:0
+test_asn1_write_bitstrings:"FF":7:"030201FE":0
 
 ASN.1 Write Bitstring / Unused bits #2
-test_asn1_write_bitstrings:"FF":6:"030202FC":4:0
+test_asn1_write_bitstrings:"FF":6:"030202FC":0
 
 ASN.1 Write Bitstring / Unused bits #3
-test_asn1_write_bitstrings:"FF":5:"030203F8":4:0
+test_asn1_write_bitstrings:"FF":5:"030203F8":0
 
 ASN.1 Write Bitstring / Unused bits #4
-test_asn1_write_bitstrings:"FF":4:"030204F0":4:0
+test_asn1_write_bitstrings:"FF":4:"030204F0":0
 
 ASN.1 Write Bitstring / Unused bits #5
-test_asn1_write_bitstrings:"FF":3:"030205E0":4:0
+test_asn1_write_bitstrings:"FF":3:"030205E0":0
 
 ASN.1 Write Bitstring / Unused bits #6
-test_asn1_write_bitstrings:"FF":2:"030206C0":4:0
+test_asn1_write_bitstrings:"FF":2:"030206C0":0
 
 ASN.1 Write Bitstring / Unused bits #7
-test_asn1_write_bitstrings:"FF":1:"03020780":4:0
+test_asn1_write_bitstrings:"FF":1:"03020780":0
 
 ASN.1 Write Bitstring / 1 trailing bit (bits 15)
-test_asn1_write_bitstrings:"0003":15:"0303010002":5:0
+test_asn1_write_bitstrings:"0003":15:"0303010002":0
 
 ASN.1 Write Bitstring / 0 bits
-test_asn1_write_bitstrings:"":0:"030100":3:0
+test_asn1_write_bitstrings:"":0:"030100":0
 
 ASN.1 Write Bitstring / long string all bits unset except trailing bits
-test_asn1_write_bitstrings:"000000000007":45:"030703000000000000":9:0
+test_asn1_write_bitstrings:"000000000007":45:"030703000000000000":0
diff --git a/tests/suites/test_suite_asn1write.function b/tests/suites/test_suite_asn1write.function
index 7dfc162..1669ca8 100644
--- a/tests/suites/test_suite_asn1write.function
+++ b/tests/suites/test_suite_asn1write.function
@@ -114,6 +114,8 @@
         ret = mbedtls_asn1_write_mpi( &data.p, data.start, &mpi );
         if( ! generic_write_finish_step( &data, expected, ret ) )
             goto exit;
+        if( expected->len > 10 && data.size == 8 )
+            data.size = expected->len - 2;
     }
 
 exit:
@@ -123,70 +125,49 @@
 /* END_CASE */
 
 /* BEGIN_CASE */
-void mbedtls_asn1_write_octet_string( data_t * str, data_t * asn1,
-                                      int buf_len, int result )
+void mbedtls_asn1_write_string( int tag, data_t *content, data_t *expected )
 {
+    generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
-    unsigned char buf[150];
-    size_t i;
-    unsigned char *p;
 
-    memset( buf, GUARD_VAL, sizeof( buf ) );
-
-
-    p = buf + GUARD_LEN + buf_len;
-
-    ret = mbedtls_asn1_write_octet_string( &p, buf + GUARD_LEN, str->x, str->len );
-
-    /* Check for buffer overwrite on both sides */
-    for( i = 0; i < GUARD_LEN; i++ )
+    for( data.size = 0; data.size < expected->len + 1; data.size++ )
     {
-        TEST_ASSERT( buf[i] == GUARD_VAL );
-        TEST_ASSERT( buf[GUARD_LEN + buf_len + i] == GUARD_VAL );
+        if( ! generic_write_start_step( &data ) )
+            goto exit;
+        switch( tag )
+        {
+            case MBEDTLS_ASN1_OCTET_STRING:
+                ret = mbedtls_asn1_write_octet_string(
+                    &data.p, data.start, content->x, content->len );
+                break;
+            case MBEDTLS_ASN1_UTF8_STRING:
+                ret = mbedtls_asn1_write_utf8_string(
+                    &data.p, data.start,
+                    (const char *) content->x, content->len );
+                break;
+            case MBEDTLS_ASN1_PRINTABLE_STRING:
+                ret = mbedtls_asn1_write_printable_string(
+                    &data.p, data.start,
+                    (const char *) content->x, content->len );
+                break;
+            case MBEDTLS_ASN1_IA5_STRING:
+                ret = mbedtls_asn1_write_ia5_string(
+                    &data.p, data.start,
+                    (const char *) content->x, content->len );
+                break;
+            default:
+                ret = mbedtls_asn1_write_tagged_string(
+                    &data.p, data.start, tag,
+                    (const char *) content->x, content->len );
+        }
+        if( ! generic_write_finish_step( &data, expected, ret ) )
+            goto exit;
+        if( expected->len > 10 && data.size == 8 )
+            data.size = expected->len - 2;
     }
 
-    if( result >= 0 )
-    {
-        TEST_ASSERT( (size_t) ret == asn1->len );
-        TEST_ASSERT( p + asn1->len == buf + GUARD_LEN + buf_len );
-
-        TEST_ASSERT( memcmp( p, asn1->x, asn1->len ) == 0 );
-    }
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
-void mbedtls_asn1_write_ia5_string( char * str, data_t * asn1,
-                                    int buf_len, int result )
-{
-    int ret;
-    unsigned char buf[150];
-    size_t str_len;
-    size_t i;
-    unsigned char *p;
-
-    memset( buf, GUARD_VAL, sizeof( buf ) );
-
-    str_len = strlen( str );
-
-    p = buf + GUARD_LEN + buf_len;
-
-    ret = mbedtls_asn1_write_ia5_string( &p, buf + GUARD_LEN, str, str_len );
-
-    /* Check for buffer overwrite on both sides */
-    for( i = 0; i < GUARD_LEN; i++ )
-    {
-        TEST_ASSERT( buf[i] == GUARD_VAL );
-        TEST_ASSERT( buf[GUARD_LEN + buf_len + i] == GUARD_VAL );
-    }
-
-    if( result >= 0 )
-    {
-        TEST_ASSERT( (size_t) ret == asn1->len );
-        TEST_ASSERT( p + asn1->len == buf + GUARD_LEN + buf_len );
-
-        TEST_ASSERT( memcmp( p, asn1->x, asn1->len ) == 0 );
-    }
+exit:
+    mbedtls_free( data.output );
 }
 /* END_CASE */
 
@@ -243,44 +224,25 @@
 
 /* BEGIN_CASE */
 void test_asn1_write_bitstrings( data_t *bitstring, int bits,
-                                 data_t *expected_asn1, int result,
-                                 int is_named )
+                                 data_t *expected, int is_named )
 {
+    generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
     int ret;
-    size_t i;
-    unsigned char buf[150];
-    unsigned char *p;
+    int ( *func )( unsigned char **p, unsigned char *start,
+                   const unsigned char *buf, size_t bits ) =
+        ( is_named ? mbedtls_asn1_write_named_bitstring :
+          mbedtls_asn1_write_bitstring );
 
-    memset( buf, GUARD_VAL, sizeof( buf ) );
-
-    p = buf + GUARD_LEN + expected_asn1->len;
-
-    if ( is_named == 0 )
+    for( data.size = 0; data.size < expected->len + 1; data.size++ )
     {
-        ret = mbedtls_asn1_write_bitstring( &p,
-                                            buf,
-                                            (unsigned char *)bitstring->x,
-                                            (size_t) bits );
-    }
-    else
-    {
-        ret = mbedtls_asn1_write_named_bitstring( &p,
-                                                  buf,
-                                                  (unsigned char *)bitstring->x,
-                                                  (size_t) bits );
-    }
-    TEST_ASSERT( ret == result );
-
-    /* Check for buffer overwrite on both sides */
-    for( i = 0; i < GUARD_LEN; i++ )
-    {
-        TEST_ASSERT( buf[i] == GUARD_VAL );
-        TEST_ASSERT( buf[GUARD_LEN + expected_asn1->len + i] == GUARD_VAL );
+        if( ! generic_write_start_step( &data ) )
+            goto exit;
+        ret = ( *func )( &data.p, data.start, bitstring->x, bits );
+        if( ! generic_write_finish_step( &data, expected, ret ) )
+            goto exit;
     }
 
-    if ( result >= 0 )
-    {
-        TEST_ASSERT( memcmp( p, expected_asn1->x, expected_asn1->len ) == 0 );
-    }
+exit:
+    mbedtls_free( data.output );
 }
 /* END_CASE */