How do you manage test data in a large Selenium automation framework?

# Environment-specific, never test-specific
baseUrl=https://staging.automateqa.online
apiUrl=https://api.staging.automateqa.online
defaultTimeout=15
browser=chrome
headless=false

public class ConfigManager {
    private static Properties config = new Properties();

    static {
        try (FileInputStream fis = new FileInputStream("src/test/resources/config.properties")) {
            config.load(fis);
        } catch (IOException e) {
            throw new RuntimeException("Cannot load config.properties");
        }
    }

    public static String get(String key) {
        return System.getProperty(key, config.getProperty(key));
    }
}
// Usage: ConfigManager.get("baseUrl")

@DataProvider(name = "loginScenarios")
public Object[][] loginData() throws Exception {
    return ExcelUtils.getSheetData("src/test/resources/testdata/TestData.xlsx", "Login");
}

@Test(dataProvider = "loginScenarios")
public void loginTest(String user, String pass, String expectedResult) { ... }

// src/test/resources/testdata/users.json
[
  {"username": "admin@test.com",    "password": "admin123",  "role": "ADMIN"},
  {"username": "readonly@test.com", "password": "read456",   "role": "VIEWER"},
  {"username": "manager@test.com",  "password": "mgr789",    "role": "MANAGER"}
]

// Read JSON test data
ObjectMapper mapper = new ObjectMapper();
List<UserData> users = mapper.readValue(
    new File("src/test/resources/testdata/users.json"),
    new TypeReference<List<UserData>>() {});

public class TestDataFactory {

    public static String createTestUser(String role) {
        String email = "test_" + System.currentTimeMillis() + "@automateqa.online";
        RestAssured
            .given()
            .header("Authorization", "Bearer " + getAdminToken())
            .body("{\"email\":\"" + email + "\",\"role\":\"" + role + "\"}")
            .post("/api/users");
        return email;
    }

    public static String createTestOrder(String userId, float amount) {
        Response r = RestAssured
            .given().header("Authorization", "Bearer " + getAdminToken())
            .body("{\"userId\":\"" + userId + "\",\"amount\":" + amount + "}")
            .post("/api/orders");
        return r.jsonPath().getString("orderId");
    }
}

// In test
@BeforeMethod
public void setUp() {
    testUserEmail = TestDataFactory.createTestUser("ADMIN");
}

@AfterMethod
public void cleanUp() {
    TestDataFactory.deleteUser(testUserEmail); // API cleanup
}

// For complex test data that''s hard to create via API
public class DatabaseUtils {
    private static Connection conn;

    public static void insertTestProduct(String name, double price) throws Exception {
        PreparedStatement ps = conn.prepareStatement(
            "INSERT INTO products (name, price, is_test_data) VALUES (?, ?, true)"
        );
        ps.setString(1, name);
        ps.setDouble(2, price);
        ps.executeUpdate();
    }

    public static void cleanTestData() throws Exception {
        conn.createStatement().execute("DELETE FROM products WHERE is_test_data = true");
    }
}