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Data-Driven Testing best practices

This document explains the best practices when working with data-driven testing.

Requirements
  • Katalon Studio 7.0+ (Free or Enterprise edition)
  • A Test Data sheet: Excel/CSV with user credentials
  • Captured Test Objects: Login form elements (username, password, login button).

Data-driven testing works best in testing scenarios involving multiple data sources, such as various logins with different user credentials. Testing approach becomes simple: Design a single, data‑driven login test case that reads user credentials from an external data source (e.g., Excel or CSV), and execute it with multiple data rows representing valid users, invalid credentials, and locked accounts.

By parameterizing the username, password, and expected outcome (SUCCESS, FAILURE, ACCOUNT_LOCKED), you avoid creating 5+ separate test cases, improve coverage of positive and negative scenarios, and make it easy to add or update user types simply by editing the test data file instead of changing test logic.

Get Started​

Assume that there's a data structure as below:

| username | password | expectedResult |
|---|---|---|
| john@test.com | Pass123! | SUCCESS |
| jane@test.com | Pass456! | SUCCESS |
| invalid@test | WrongPass | FAILURE |
| locked@test | Pass789! | ACCOUNT_LOCKED |

Step 1: Create a Test Data File from Test Data sheet​

  1. Go to File > New > Test Data
Data-Driven Testing best practices image 3

  1. Name: LoginCredentials

  2. Select Excel File (or CSV)

  3. Browse and select your Excel file

  4. Check "Use first row as header"

  5. Click OK and save

Step 2: Create Test Case with Variables​

  1. File > New > Test Case → Name: Login_DDT

  2. Click Variables tab

  3. Add variables:

NameTypeDefault
usernameStringjohn@test.com
passwordStringPass123!
expectedResultStringSUCCESS

Step 3: Write Test Script​

This example script below navigates to the login site, input credentials, and validate if the outcome is as described in the test data sheet.

import com.kms.katalon.core.webui.keyword.WebUiBuiltInKeywords as WebUI

// Navigate to login page
WebUI.navigateToUrl('https://example.com/login')

// Fill login form with variables
WebUI.setText(findTestObject('Object Repository/Username_Input'), username)
WebUI.setText(findTestObject('Object Repository/Password_Input'), password)
WebUI.click(findTestObject('Object Repository/Login_Button'))

// Verify result based on expected outcome
if (expectedResult == 'SUCCESS') {
    WebUI.verifyElementPresent(findTestObject('Object Repository/Dashboard_Page'), 5)
    println("✓ Login successful for: ${username}")
} else if (expectedResult == 'FAILURE') {
    WebUI.verifyElementPresent(findTestObject('Object Repository/ErrorMessage'), 5)
    println("✓ Error handling verified for: ${username}")
} else if (expectedResult == 'ACCOUNT_LOCKED') {
    WebUI.verifyElementPresent(findTestObject('Object Repository/LockedMessage'), 5)
    println("✓ Account locked message verified for: ${username}")
}

Step 4: Configure Data Binding​

  1. In test case, click Data Binding tab

  2. Click Add in Test Data section

  3. Select LoginCredentials file

  4. In Variable Binding section:

    • Map username → Column: username

    • Map password → Column: password

    • Map expectedResult → Column: expectedResult

Data-Driven Testing best practices image 2
  1. Click Map All (if column names match variable names)
Data-Driven Testing best practices image 1

Step 5: Execute Test​

  1. Click Run button

  2. Katalon executes test case once for each data row (4 iterations)

  3. View results in Log Viewer:

Test Cases/Login_DDT (2.5s)
├── Iteration 1 - username=john@test.com, password=Pass123! (0.6s) - PASSED
├── Iteration 2 - username=jane@test.com, password=Pass456! (0.6s) - PASSED
├── Iteration 3 - username=invalid@test, password=WrongPass (0.7s) - PASSED
└── Iteration 4 - username=locked@test, password=Pass789! (0.6s) - PASSED

Step 6: Error Handling​

// Validate data before execution
if (username == null || username.isEmpty()) {
    throw new Exception("Username cannot be empty") 
    }
if (!(username =~ /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/)) {
    throw new Exception("Invalid email format: ${username}") 
    } 
// Handle missing password
String pwd = (password == null || password.isEmpty()) 
    ? "DefaultPass123" 
    : password println("✓ Data validation passed for: ${username}")

Common Pitfalls to Avoid​

When designing variables and referencing external data files for DDT, adherence to clean code naming conventions is essential:

  1. Global Variables: When declaring global variables, use the Uppercase string convention.

  2. Local/Test Cases Variables: Use CamelCase when declaring local or test case variables.

  3. Variable Naming: Avoid using variable names that have no meaning or using keywords. Instead, ensure that you add appropriate comments or descriptions to define the variable's purpose.

  4. Data File References: Ensure that you select the "Use relative path" option in the file information settings when referencing data files.

Scaling Recommendations​

  • Organize data files by feature (Authentication/, Checkout/, etc.)

  • Use database data sources for large datasets (100+ rows)

  • Implement CI/CD integration to run DDT automatically

  • Use Katalon TestOps for centralized reporting

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