Add test connection endpoint for warehouse connections (Snowflake)

[gagantrivedi]

Endpoint

POST /api/v1/organisations/{organisation_pk}/integrations/warehouse-connections/{id}/test/

Request body

{}

Empty — all config and the private key are already stored on the connection.

Response (200 OK) — success

{
  "success": true,
  "tested_at": "2026-04-17T10:05:00Z"
}

Response (200 OK) — failure

{
  "success": false,
  "tested_at": "2026-04-17T10:05:00Z",
  "error": "SQL access control error: Insufficient privileges to operate on warehouse 'COMPUTE_WH'"
}

What the server does

1. Open a Snowflake session using the stored account_identifier, user, and decrypted private key.
2. Run SELECT 1 against the configured warehouse / database / schema — implicitly validates auth + warehouse access + db/schema access in one call.
3. Run LIST @<stage> — validates the stage exists and is reachable.

First error wins. Raw Snowflake error message is returned as error.

Side effects

Updates the connection row:

• last_tested_at = now
• status → connected on success, error on failure
• last_error = the error string (or null on success)

Notes

• Always returns 200 when the test ran, regardless of outcome. Reserve 4xx/5xx for request-level problems (unauthorized, connection not found, server error).
• Sync. Full probe is <5s.