How to use the etlhelper.DbParams function in etlhelper

def test_postgres_connect(monkeypatch):
    db_params = DbParams(dbtype='PG',
                         host='server', port='1521', dbname='testdb',
                         user='testuser', odbc_driver='test driver')
    monkeypatch.setenv('DB_PASSWORD', 'mypassword')
    expected_conn_str = 'host=server port=1521 dbname=testdb user=testuser password=mypassword'
    mock_connect = Mock()
    monkeypatch.setattr(psycopg2, 'connect', mock_connect)

    # Act
    helper = PostgresDbHelper()
    helper.connect(db_params, 'DB_PASSWORD')

    # Assert
    mock_connect.assert_called_with(expected_conn_str)

These currently run against internal BGS instance.
"""
# pylint: disable=unused-argument, missing-docstring
from datetime import datetime, date
import os
from textwrap import dedent

import cx_Oracle
import pytest

from etlhelper import connect, get_rows, copy_rows, DbParams
from etlhelper.exceptions import ETLHelperConnectionError
from test.conftest import db_is_unreachable

# Skip these tests if database is unreachable
ORADB = DbParams.from_environment(prefix='TEST_ORACLE_')
if db_is_unreachable(ORADB.host, ORADB.port):
    pytest.skip('Oracle test database is unreachable', allow_module_level=True)


# -- Tests here --

def test_connect():
    conn = connect(ORADB, 'TEST_ORACLE_PASSWORD')
    assert isinstance(conn, cx_Oracle.Connection)


def test_connect_wrong_password(monkeypatch):
    monkeypatch.setitem(os.environ, 'TEST_ORACLE_PASSWORD', 'bad_password')
    with pytest.raises(ETLHelperConnectionError):
        connect(ORADB, 'TEST_ORACLE_PASSWORD')

def test_sqlserver_connect(monkeypatch):
    db_params = DbParams(dbtype='MSSQL',
                         host='server', port='1521', dbname='testdb',
                         user='testuser', odbc_driver='test driver')
    monkeypatch.setenv('DB_PASSWORD', 'mypassword')
    expected_conn_str = ('DRIVER=test driver;SERVER=tcp:server;PORT=1521;'
                         'DATABASE=testdb;UID=testuser;PWD=mypassword')

    mock_connect = Mock()
    monkeypatch.setattr(pyodbc, 'connect', mock_connect)

    # Act
    helper = SqlServerDbHelper()
    helper.connect(db_params, 'DB_PASSWORD')

    # Assert
    mock_connect.assert_called_with(expected_conn_str)

def test_from_db_params_not_registered():
    """
    Tests helpful error message on attempt to choose unregistered db_params
    type.
    """
    db_params = MagicMock(DbParams)
    db_params.dbtype = 'Not a real type'

    with pytest.raises(ETLHelperHelperError,
                       match=r'Unsupported DbParams.dbtype.*'):
        DB_HELPER_FACTORY.from_db_params(db_params)

def test_sqlite_dbparam_not_supported():
    sqlitedb = DbParams(
        dbtype='SQLITE',
        filename='sqlite.db',
        dbname='etlhelper',
        user='etlhelper_user')

    with pytest.raises(ValueError):
        sqlitedb.is_reachable()

def sqlitedb(tmp_path):
    """Get DbParams for temporary SQLite database."""
    filename = f'{tmp_path.absolute()}.db'
    yield DbParams(dbtype='SQLITE', filename=filename)

def test_sqlserver_sqlalchemy_connect(monkeypatch):
    db_params = DbParams(dbtype='MSSQL',
                         host='server', port='1521', dbname='testdb',
                         user='testuser', odbc_driver='test driver')
    monkeypatch.setenv('DB_PASSWORD', 'mypassword')
    helper = SqlServerDbHelper()
    conn_str = helper.get_sqlalchemy_connection_string(db_params, 'DB_PASSWORD')
    expected_conn_str = 'mssql+pyodbc://testuser:mypassword@server:1521/testdb?driver=test+driver'

    assert conn_str == expected_conn_str

def test_postgres_sqlalchemy_connect(monkeypatch):
    db_params = DbParams(dbtype='PG',
                         host='server', port='1521', dbname='testdb',
                         user='testuser')
    monkeypatch.setenv('DB_PASSWORD', 'mypassword')
    helper = PostgresDbHelper()
    conn_str = helper.get_sqlalchemy_connection_string(db_params, 'DB_PASSWORD')
    expected_conn_str = 'postgresql://testuser:mypassword@server:1521/testdb'

    assert conn_str == expected_conn_str

def test_oracle_sqlalchemy_conn_string(monkeypatch):
    db_params = DbParams(dbtype='ORACLE',
                         host='server', port='1521', dbname='testdb',
                         user='testuser')
    monkeypatch.setenv('DB_PASSWORD', 'mypassword')
    helper = OracleDbHelper()
    conn_str = helper.get_sqlalchemy_connection_string(db_params, 'DB_PASSWORD')
    expected_conn_str = ('oracle://testuser:mypassword@server:1521/testdb')

    assert conn_str == expected_conn_str

def params():
    return DbParams(dbtype='ORACLE', odbc_driver='test driver', host='testhost',
                    port=1521, dbname='testdb', user='testuser')