diff --git a/vasl_templates/webapp/tests/test_vassal.py b/vasl_templates/webapp/tests/test_vassal.py
index f301b79..1edc66c 100644
--- a/vasl_templates/webapp/tests/test_vassal.py
+++ b/vasl_templates/webapp/tests/test_vassal.py
@@ -1,6 +1,7 @@
 """ Test VASSAL integration. """
 
 import os
+import traceback
 import re
 import json
 import base64
@@ -877,14 +878,32 @@ def run_vassal_tests( webapp, func, vasl_extns_type=None,
             assert False, "Can't find a valid combination of VASSAL and VASL."
 
     # run the test for each VASSAL+VASL
-    for vassal_version in vassal_versions:
-        for vasl_version in vasl_versions:
-            if not VassalShim.is_compatible_version( vassal_version, vasl_version ):
-                continue
-            webapp.control_tests \
-                .set_vassal_version( vassal_version ) \
-                .set_vasl_version( vasl_version, vasl_extns_type )
-            func()
+    log_fname = os.environ.get( "RUN_VASSAL_TESTS_LOG" ) # nb: define this to log activity
+    log_file = open( log_fname, "w", encoding="utf-8" ) if log_fname else None #pylint: disable=consider-using-with
+    def log( fmt, *args, **kwargs ):
+        if log_file:
+            print( fmt.format( *args, **kwargs ), file=log_file )
+            log_file.flush()
+    try:
+        for vassal_version in vassal_versions:
+            for vasl_version in vasl_versions:
+                if not VassalShim.is_compatible_version( vassal_version, vasl_version ):
+                    continue
+                log( "Running tests for VASSAL {}, VASL {}...", vassal_version, vasl_version )
+                webapp.control_tests \
+                    .set_vassal_version( vassal_version ) \
+                    .set_vasl_version( vasl_version, vasl_extns_type )
+                try:
+                    func()
+                    log ( "- OK.\n" )
+                except Exception as exc: #pylint: disable=broad-except
+                    log( "- Failed: {}\n{}", exc,
+                        re.sub( "^", "    ", traceback.format_exc(), flags=re.MULTILINE )
+                    )
+                    #raise
+    finally:
+        if log_file:
+            log_file.close()
 
 # ---------------------------------------------------------------------