Add cipher_set_padding() (no effect yet)

Fix pattern in tests/.gitignore along the way.
diff --git a/tests/suites/test_suite_cipher.function b/tests/suites/test_suite_cipher.function
index b7115d9..3024623 100644
--- a/tests/suites/test_suite_cipher.function
+++ b/tests/suites/test_suite_cipher.function
@@ -252,6 +252,19 @@
     TEST_ASSERT( 0 == cipher_free_ctx( &ctx_enc ) );
 END_CASE
 
+BEGIN_CASE
+set_padding:cipher_id:pad_mode:ret:
+    const cipher_info_t *cipher_info;
+    cipher_context_t ctx;
+
+    cipher_info = cipher_info_from_type( {cipher_id} );
+    TEST_ASSERT( NULL != cipher_info );
+    TEST_ASSERT( 0 == cipher_init_ctx( &ctx, cipher_info ) );
+
+    TEST_ASSERT( {ret} == cipher_set_padding_mode( &ctx, {pad_mode} ) );
+
+    TEST_ASSERT( 0 == cipher_free_ctx( &ctx ) );
+END_CASE
 
 BEGIN_CASE
 cipher_selftest: