To DB schema validation error message add diff of offending lines.

diff --git a/plomtask/db.py b/plomtask/db.py
index a8bdbec166fedbcfd3531717917b1291d364efce..b7291dba4245852097f7dc3146e9b1d6d355bbcf 100644 (file)
--- a/plomtask/db.py
+++ b/plomtask/db.py
@@ -1,5 +1,6 @@
 """Database management."""
 from os.path import isfile
+from difflib import Differ
 from sqlite3 import connect as sql_connect
 from plomtask.misc import HandledException
 
@@ -29,11 +30,13 @@ class DatabaseFile:
     def validate_schema(self):
         """Compare found schema with what's stored at PATH_DB_SCHEMA."""
         sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
-        msg_wrong_schema = 'Database has wrong tables schema.'
+        msg_err = 'Database has wrong tables schema. Diff:\n'
         with sql_connect(self.path) as conn:
             schema_rows = [r[0] for r in conn.execute(sql_for_schema) if r[0]]
             retrieved_schema = ';\n'.join(schema_rows) + ';'
             with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
                 stored_schema = f.read().rstrip()
                 if stored_schema != retrieved_schema:
-                    raise HandledException(msg_wrong_schema)
+                    diff_msg = Differ().compare(retrieved_schema.splitlines(),
+                                                stored_schema.splitlines())
+                    raise HandledException(msg_err + '\n'.join(diff_msg))