[gmime] Fixed test-filters logic to handle unsupported charset conversion cleaner

[Rico Tzschichholz <ricotz src gnome org>]

commit 1b9cd7981b35c67f16bd966e88b4feec434a0302
Author: Jeffrey Stedfast <jestedfa microsoft com>
Date:   Sun Feb 16 09:44:57 2020 -0500

    Fixed test-filters logic to handle unsupported charset conversion cleaner
    
    Partial fix for issue #81

 tests/test-filters.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/tests/test-filters.c b/tests/test-filters.c
index df39861d..365c195f 100644
--- a/tests/test-filters.c
+++ b/tests/test-filters.c
@@ -113,12 +113,15 @@ test_charset_conversion (const char *datadir, const char *base, const char *from
        
        testsuite_check ("%s (%s %s -> %s)", what, base, from, to);
        
+       if (!(filter = g_mime_filter_charset_new (from, to))) {
+               testsuite_check_failed ("%s failed: system does not support conversion from %s to %s", what, 
from, to);
+               return;
+       }
+       
        actual = g_byte_array_new ();
        stream = g_mime_stream_mem_new_with_byte_array (actual);
        g_mime_stream_mem_set_owner ((GMimeStreamMem *) stream, FALSE);
        
-       filter = g_mime_filter_charset_new (from, to);
-       
        name = g_strdup_printf ("%s.%s.txt", base, from);
        path = g_build_filename (datadir, name, NULL);
        pump_data_through_filter (filter, path, stream, TRUE, TRUE);