Pretty message when dropping a non-existent database

bigchaindb/commands/bigchain.py

@@ -12,7 +12,8 @@ import sys
 from bigchaindb.common import crypto
 from bigchaindb.common.exceptions import (StartupError,
                                           DatabaseAlreadyExists,
-                                          KeypairNotFoundException)
+                                          KeypairNotFoundException,
+                                          DatabaseDoesNotExist)
 import bigchaindb
 from bigchaindb import backend, processes
 from bigchaindb.backend import schema
@@ -166,7 +167,10 @@ def run_drop(args):
 
     conn = backend.connect()
     dbname = bigchaindb.config['database']['name']
-    schema.drop_database(conn, dbname)
+    try:
+        schema.drop_database(conn, dbname)
+    except DatabaseDoesNotExist:
+        print("Cannot drop '{name}'. The database does not exist.".format(name=dbname), file=sys.stderr)
 
 
 @configure_bigchaindb

tests/commands/test_commands.py

@@ -149,6 +149,18 @@ def test_drop_db_when_interactive_yes(mock_db_drop, monkeypatch):
     assert mock_db_drop.called
 
 
+@patch('bigchaindb.backend.schema.drop_database')
+def test_drop_db_when_db_does_not_exist(mock_db_drop, capsys):
+    from bigchaindb.commands.bigchain import run_drop
+    from bigchaindb.common.exceptions import DatabaseDoesNotExist
+    args = Namespace(config=None, yes=True)
+    mock_db_drop.side_effect = DatabaseDoesNotExist
+
+    run_drop(args)
+    output_message = capsys.readouterr()[1]
+    assert output_message == "Cannot drop 'bigchain'. The database does not exist.\n"
+
+
 @patch('bigchaindb.backend.schema.drop_database')
 def test_drop_db_does_not_drop_when_interactive_no(mock_db_drop, monkeypatch):
     from bigchaindb.commands.bigchain import run_drop