Deleting from an unknown table raises error

If the table exists then we deletes are idempotent

moto/dynamodb2/models.py

@@ -659,7 +659,7 @@ class DynamoDBBackend(BaseBackend):
         return item
 
     def delete_item(self, table_name, keys):
-        table = self.tables.get(table_name)
+        table = self.get_table(table_name)
         if not table:
             return None
         hash_key, range_key = self.get_keys_value(table, keys)

moto/dynamodb2/responses.py

@@ -418,6 +418,11 @@ class DynamoHandler(BaseResponse):
         name = self.body['TableName']
         keys = self.body['Key']
         return_values = self.body.get('ReturnValues', '')
+        table = dynamodb_backend2.get_table(name)
+        if not table:
+            er = 'com.amazonaws.dynamodb.v20120810#ConditionalCheckFailedException'
+            return self.error(er)
+
         item = dynamodb_backend2.delete_item(name, keys)
         if item and return_values == 'ALL_OLD':
             item_dict = item.to_json()

tests/test_dynamodb2/test_dynamodb_table_without_range_key.py

@@ -199,7 +199,8 @@ def test_delete_item():
 
     table.count().should.equal(0)
 
-    item.delete().should.equal(False)
+    # Deletes are idempotent and 'False' here would imply an error condition
+    item.delete().should.equal(True)
 
 
 @requires_boto_gte("2.9")