Add test cases for ASN.1 ENUMERATED tag

Add test cases for writing and parsing ASN.1 ENUMERATED
tag values.

Signed-off-by: Mykhailo Sopiha <mykhailo.sopiha@linaro.org>
diff --git a/tests/suites/test_suite_asn1write.function b/tests/suites/test_suite_asn1write.function
index b69f6b5..21465c7 100644
--- a/tests/suites/test_suite_asn1write.function
+++ b/tests/suites/test_suite_asn1write.function
@@ -117,6 +117,27 @@
 }
 /* END_CASE */
 
+
+/* BEGIN_CASE */
+void mbedtls_asn1_write_enum( int val, data_t *expected )
+{
+    generic_write_data_t data = { NULL, NULL, NULL, NULL, 0 };
+    int ret;
+
+    for( data.size = 0; data.size < expected->len + 1; data.size++ )
+    {
+        if( ! generic_write_start_step( &data ) )
+            goto exit;
+        ret = mbedtls_asn1_write_enum( &data.p, data.start, val );
+        if( ! generic_write_finish_step( &data, expected, ret ) )
+            goto exit;
+    }
+
+exit:
+    mbedtls_free( data.output );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_BIGNUM_C */
 void mbedtls_asn1_write_mpi( data_t *val, data_t *expected )
 {