📌 1. What is TestNG?

• TestNG (Test Next Generation) is a testing framework inspired by JUnit and NUnit.

• It was created by Cédric Beust to overcome the limitations of JUnit (3 & 4) and make testing more powerful.

• It supports unit testing, functional testing, integration testing, and end-to-end testing.

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📌 2. Why TestNG came?

Before TestNG, most people used JUnit in Java. But:

• ❌ JUnit did not support parallel execution.

• ❌ JUnit had limited annotations.

• ❌ Grouping tests (e.g., smoke vs regression) was not possible.

• ❌ No built-in reporting → only console output.

• ❌ Parameterization was hard to achieve.

👉 To solve these problems, TestNG was introduced.

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📌 3. What problems does TestNG solve?

✅ Supports annotations (easy to define pre/post conditions).
✅ Allows grouping (smoke, regression, sanity).
✅ Supports parallel execution → saves time.
✅ Provides dependency testing (dependsOnMethods, dependsOnGroups).
✅ Built-in HTML reports.
✅ Allows parameterization (via testng.xml or @DataProvider).
✅ Integrates seamlessly with Maven, Jenkins, Selenium.

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📌 4. Structure of TestNG Framework

Let’s break the TestNG structure into 3 levels:

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🔹 (A) TestNG Annotations

These control the lifecycle of tests.

👉 Example:

public class LoginTest {

    @BeforeClass
    public void setup() {
        System.out.println("Launch browser");
    }

    @Test(priority = 1)
    public void validLogin() {
        System.out.println("Valid login test");
    }

    @Test(priority = 2)
    public void invalidLogin() {
        System.out.println("Invalid login test");
    }

    @AfterClass
    public void tearDown() {
        System.out.println("Close browser");
    }
}

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🔹 (B) testng.xml (Suite File)

The test suite configuration file.

Example:

<!DOCTYPE suite SYSTEM "https://testng.org/testng-1.0.dtd">
<suite name="RegressionSuite" parallel="false">

    <parameter name="browser" value="chrome"/>
    <parameter name="env" value="qa"/>

    <test name="LoginTests">
        <classes>
            <class name="com.salesinventory.tests.LoginTest"/>
            <class name="com.salesinventory.tests.DashboardTest"/>
        </classes>
    </test>

    <test name="CheckoutTests">
        <classes>
            <class name="com.salesinventory.tests.CheckoutTest"/>
        </classes>
    </test>

</suite>

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🔹 (C) Reports

After execution, TestNG automatically generates reports in:
📂 test-output folder →

• index.html (summary report)

• emailable-report.html (can be emailed)

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📌 5. How TestNG fits in Automation Framework

Selenium Tests (@Test methods)
        ↓
TestNG Annotations (@Before/After, @Test)
        ↓
testng.xml (Suite: smoke, regression, parallel)
        ↓
Maven (mvn clean test -DsuiteXmlFile=regression.xml)
        ↓
Jenkins (automated CI/CD job)
        ↓
Reports (TestNG + Extent + Screenshots + Logs)

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✅ In Summary

• What is TestNG? → A testing framework for Java (next-gen JUnit).

• Why it came? → To overcome JUnit limitations.

• What problem it solves? → Grouping, parallel execution, parameterization, reporting.

• Structure? → Annotations, testng.xml, Reports.

📌 1. TestNG Annotations Overview

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📌 2. @Test Annotation – All Attributes

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📌 3. @Before/@After Annotations Attributes

Notes:

• alwaysRun=true ensures execution even if a dependent configuration fails.

• groups in BeforeGroups/AfterGroups must match group names in @Test.

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📌 4. DataProvider Annotation

• Supplies multiple data sets to a test.

• Must return Object[][] or Iterator<Object[]>.

@DataProvider(name="loginData")
public Object[][] getData() {
    return new Object[][] {
        {"user1","pass1"},
        {"user2","pass2"}
    };
}

@Test(dataProvider="loginData")
public void loginTest(String username, String password) {
    System.out.println(username + " | " + password);
}

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📌 5. @Parameters & @Optional

<parameter name="browser" value="chrome"/>
<parameter name="env" value="qa"/>

@Parameters({"browser", "env"})
@BeforeTest
public void setup(@Optional("chrome") String browser, String env) {
    System.out.println(browser + " | " + env);
}

• @Optional provides default value if not specified in XML.

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📌 6. @Factory

• Dynamically creates instances of test classes.

@Factory
public Object[] createInstances() {
    return new Object[] { new TestClass(1), new TestClass(2) };
}

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📌 7. @Listeners

• Attach listeners to a test class for logging, reporting, or screenshots.

@Listeners(com.salesinventory.utils.ExtentReportListener.class)
public class LoginTest { }

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📌 8. Execution Flow of Annotations

@BeforeSuite
    @BeforeTest
        @BeforeGroups (if any)
            @BeforeClass
                @BeforeMethod
                    @Test
                @AfterMethod
            @AfterClass
        @AfterGroups (if any)
    @AfterTest
@AfterSuite

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📌 9. Summary Table – TestNG All Annotations + Attributes

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✅ With this table, you have every TestNG annotation and attribute — fully detailed for interviews, practical automation, and CI/CD frameworks.