Python unit test: Database connection validation

Last update on December 21 2024 07:48:52 (UTC/GMT +8 hours)

Write a Python unit test program to check if a database connection is successful.

Sample Solution:

Python Code:

# Import the 'unittest' module for writing unit tests.
import unittest
# Import the 'sqlite3' module for working with SQLite databases.
import sqlite3
# Define a test case class 'TestDatabaseConnection' that inherits from 'unittest.TestCase'.
class TestDatabaseConnection(unittest.TestCase):
    # Define a test method 'test_database_connection' to test database connection.
    def test_database_connection(self):
        # Create a database connection in memory.
        conn = sqlite3.connect(':memory:')
        # Create a cursor to interact with the database.
        cursor = conn.cursor()
        # Execute a simple query to select the value 1.
        cursor.execute("SELECT 1")
        # Fetch the result of the query.
        result = cursor.fetchone()
        # Close the cursor and the database connection.
        cursor.close()
        conn.close()
        # Assert that the fetched result is as expected, which should be a tuple containing 1.
        self.assertEqual(result, (1,))
# Check if the script is run as the main program.
if __name__ == '__main__':
    # Run the test cases using 'unittest.main()'.
    unittest.main()

Sample Output:

Ran 1 test in 0.001s
OK

Explanation:

The unittest module in Python can be used with a suitable database library such as sqlite3, psycopg2, or mysql-connector-python.

In the above exercise, the test_database_connection method tests if a database connection is successful. Inside the method, we create a database connection to an in-memory SQLite database using sqlite3.connect(':memory:'). We then create a cursor to execute SQL queries on the database.

In this case, we execute a simple query "SELECT 1" and fetch the result using cursor.fetchone(). The expected result is a tuple (1,).

At the end, we close both the cursor and the database connection by calling cursor.close() and conn.close().

Flowchart:

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