Issue #453 Add support for custom driver detector

[amanangira]

Issue #453

Description of changes:

• Add support to register user provided driver detectors and export DBAttribute
• Add helpers for unit tests for snowflake custom driver

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[amanangira]

I am looking for help on how I can test registering of a custom driver detector and test it's usage. Since when using DATA-DOG/sqlmock the driver name is always sqlmock (reference) which never would check for the intended driver when working with the DB mock.

What I intend to do -

1. Create a unit test case similar to the existing TestOracle to test a custom registered driver detector snowflake.
2. Use registerSnowflakeDriver to register a snowflake driver detector.
3. Use mockSnowflakeDB to mock the Ping queries for a snowflake and test it using capturePing.

Step 2 and 3 refer to code in this file.

[amanangira]

Hi @wangzlei, did you get a chance to look into the test cases?

[amanangira]

I am not sure whom to tag here. @wangzlei can you direct me?