Skip to content

Session 45 TestNG DataProvider, Serial vs Parallel Execution (Complete Real Time Notes)

🔹 What is @DataProvider?

  • @DataProvider is a TestNG annotation used for data-driven testing.

  • It allows you to pass multiple sets of data to the same test method.

🧪 Where is it used?

  • Commonly used in:

    • Web automation (Selenium)

    • API Testing

    • Cross Browser Testing

    • Form validations with different data

    • Data-driven business scenarios (ERP, Banking, Insurance)

❓ Why should we use it?

  1. 🔁 Reduces code duplication – one test logic, many inputs.

  2. 🔧 Better maintainability – change data in one place.

  3. 📊 Scalability – easily expand to more datasets.

  4. ✅ No hardcoding – industry standard discourages hard-coded test data.

🔹 @DataProvider Method - Technical Details

Property

Detail

Return Type

Object[][] (2D Object array)

Access Modifier

No need to specify (default)

Annotation

@DataProvider(name="...")

Attribute in Test

@Test(dataProvider = "name")

Execution Count

The test will run once per dataset row

🔹 Data Sources in Real-Time Projects

  1. Excel File (Most Common)

    • Import using Apache POI or ExcelUtils.

    • Data stored as Object[][] array.

    • ❌ Hardcoded data not recommended.

  2. Database (MySQL, Oracle)

    • Export to Excel first or fetch via JDBC.

    • Makes tests dynamic & real-time.

  3. JSON Files

    • Used in API testing, rarely in web UI tests.

  4. CSV Files, YAML, XML – Optional based on project.

🤔 Can Two @DataProvider Methods Have the Same Name?

  • ❌ No. Duplicate names are not allowed within the same class.

  • ✅ Can be same if defined in different classes, and used carefully.

🎯 Advanced Attribute – indices

@DataProvider(indices = {0, 3})

  • Runs test with only 0th and 3rd set.

  • Not a range! Just selected index positions.

🧪 Serial vs Parallel Testing in TestNG

🔹 Serial Execution (Default)

  • Only one thread is used.

  • Tests run one after another.

  • ✅ Good for debugging or when tests depend on each other.

💡 Example:

🔹 Parallel Execution (Performance Testing, Fast Results)

🔧 How?

In testng.xml, set:

📊 Levels of Parallel Execution:

Level

parallel="..."

Description

Tests

parallel="tests"

Executes entire <test> blocks in parallel

Classes

parallel="classes"

Executes all classes in parallel

Methods

parallel="methods"

Executes all test methods in parallel

🧵 What is thread-count?

  • No. of parallel threads to run.

  • Recommended:

    • Min = 2

    • Max = 5 (More than that → performance issue)

⚠️ Tip:

Even if you write parallel="tests", it won't work unless thread-count > 1 is set.

💎 God Amu's Industry-Level Secrets & Tips

💡 Real Use Case Example (ERP Form Testing):

Suppose you're testing a Sales Order form with 10 different discount slabs.
Instead of writing 10 separate test methods, you write one test with DataProvider and pass all slabs via Excel file.

💡 Secret Tip 1: Group + DataProvider Combo

@Test(dataProvider = "data", groups = {"smoke"})

  • Use groups + DataProvider together to create dynamic test suites.

💡 Secret Tip 2: Retry + DataProvider

  • Use retry logic to re-run failed tests with same data:

@RetryAnalyzer(value = RetryLogic.class)

💡 Secret Tip 3: Parallel Tests on Different Browsers

  • Run same test cases in parallel on Chrome, Firefox, Edge using DataProvider.

💡 Secret Tip 4: Use Custom DataProviderUtils

  • Create a utility class for reusable DataProvider methods (like ExcelReader).

  • ✅ Modular code

  • ✅ Reuse across multiple test classes

🧠 Quick Recap – Why DataProvider Rocks

  • ✅ Automates repetitive input testing

  • ✅ Perfect for Regression Suites

  • ✅ No hardcoded data

  • ✅ Faster Execution with Parallelism

  • ✅ Easy to integrate with Excel/DB/JSON

ओमू, हे notes तू एका झटक्यात सांगू शकतोस कुठल्याही interview मध्ये, किंवा आपल्या testing framework मध्ये plug करू शकतोस without headache.