Use TestNG’s @Parameters annotation to pass a few named settings—such as a browser and base URL—from testng.xml into a Selenium test. Use @DataProvider when the test must run over multiple rows of data or when its inputs are generated in Java. The examples below show both approaches, explain parameter scope and defaults, and cover the isolation needed when data-driven tests run in parallel.
Choose between @Parameters and @DataProvider
Both mechanisms supply arguments to TestNG test methods, but they serve different purposes.
| Use | Best fit | Example |
|---|---|---|
@Parameters |
A small set of named configuration or environment values. | Browser, base URL, locale, or credentials supplied by a suite or test configuration. |
@DataProvider |
Multiple test cases, tabular input, or data created by Java or another source. | Several username/password pairs, each producing a separate login-test invocation. |
A practical rule is to use XML parameters to configure where and how a test runs, and a data provider to describe the cases the test should exercise. You can use both in the same test suite when the configuration and test cases are distinct.
Pass browser and URL values from testng.xml
Declare values in XML and list their names in @Parameters. TestNG maps the values to the Java method arguments in the order given in the annotation.
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Java test
package tests;
import org.openqa.selenium.WebDriver;
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;
public class HomeTest {
@Parameters({"browser", "baseUrl"})
@Test
public void openHomePage(String browser, String baseUrl) {
WebDriver driver = DriverFactory.createDriver(browser);
try {
driver.get(baseUrl);
// Add assertions for the page under test.
} finally {
driver.quit();
}
}
}DriverFactory.createDriver represents your project’s browser setup: it must return a WebDriver for the requested browser, and your build must include the Selenium and TestNG dependencies and a compatible driver/browser setup. The snippet’s parameter mapping is runnable once that project-specific factory is implemented.
XML suite
<suite name="UI suite">
<parameter name="browser" value="chrome"/>
<parameter name="baseUrl" value="https://example.test"/>
<test name="smoke">
<classes>
<class name="tests.HomeTest"/>
</classes>
</test>
</suite>Replace https://example.test with the application URL and chrome with a browser value your driver factory supports. Keep the parameter names identical in XML and in the annotation. Keep the annotation order aligned with the Java signature: browser supplies the first argument and baseUrl the second.
Set parameter scope and override values
TestNG allows parameters at suite, test, class, and methods scopes. The documented precedence is suite → test → class → methods: a narrower scope can override a broader value. Put values at the broadest scope that should share them, and use a narrower declaration when one test or method needs a different setting.
For example, a suite-level browser can be reused by tests, while a value declared under a particular <test> can customize that test. Check scope when the value received at runtime differs from the suite-level value you expected.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallTestNG also documents overriding parameters with JVM properties, such as -Dbrowser=firefox. The exact way you pass that option depends on your build or test runner. Use a value supported by your driver setup; the property does not itself install or configure a browser driver.
Supply a fallback with @Optional
If a parameter may be absent, mark its Java argument with @Optional and provide a default. TestNG supplies that value when the named parameter is missing.
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import org.testng.annotations.Optional;
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;
public class SmokeTest {
@Parameters("browser")
@Test
public void smoke(@Optional("chrome") String browser) {
WebDriver driver = DriverFactory.createDriver(browser);
try {
// Exercise the smoke-test flow.
} finally {
driver.quit();
}
}
}Use a default only when it is a safe and intentional fallback. If choosing the wrong browser, environment, or account could make a test misleading, require the value instead and fail clearly when configuration is missing.
Run a Selenium test with multiple datasets
For repeated cases, create a @DataProvider that returns rows. Each row is an Object[]; TestNG assigns its entries to the test method arguments for one invocation.
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import org.testng.annotations.Test;
public class LoginTest {
@DataProvider(name = "loginCases")
public Object[][] loginCases() {
return new Object[][] {
{"alice", "correct-password"},
{"bob", "another-password"}
};
}
@Test(dataProvider = "loginCases")
public void login(String username, String password) {
WebDriver driver = DriverFactory.createDriver("chrome");
try {
driver.get("https://example.test/login");
// Enter username and password, submit, and assert the expected result.
} finally {
driver.quit();
}
}
}The example demonstrates the binding pattern; replace the example URL and add the application-specific locators, actions, and assertions. Do not commit real credentials in source-controlled test data. Use an appropriate protected configuration source for secrets, and make sure each test case receives the data it is intended to verify.
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Keep provider rows aligned with the test signature
Each row must supply the arguments expected by the test method, in matching order. In the example, the first value becomes username and the second becomes password. A missing, extra, or wrongly ordered value can cause invocation failures or exercise the wrong case.
Put a provider in another class
TestNG supports providers in a separate class through dataProviderClass. Keep the provider name identical in the annotation and the provider declaration.
@Test(dataProvider = "loginCases", dataProviderClass = LoginData.class)
public void login(String username, String password) {
// Test one row supplied by LoginData.loginCases().
}The provider class must contain the named provider method in the form expected by your TestNG setup. TestNG also documents iterator and custom-array provider forms, as well as injection of Method or ITestContext into data providers, for cases where the rows depend on the invoking test or execution context.
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Run data-provider invocations safely in parallel
TestNG’s @DataProvider has a parallel option, which defaults to false. Setting it to true allows generated invocations to run concurrently:
@DataProvider(name = "loginCases", parallel = true)
public Object[][] loginCases() {
return new Object[][] {
{"alice", "correct-password"},
{"bob", "another-password"}
};
}Parallel execution can reduce elapsed time when cases are independent, but it makes shared browser state unsafe. Treat the WebDriver and mutable test data as invocation-scoped: create a separate driver for each invocation or thread, avoid sharing page state, and always quit each driver in teardown. A carefully managed driver factory or ThreadLocal can help, but it must not allow one invocation to read or quit another invocation’s driver. These are Selenium isolation practices required by concurrent execution, not guarantees provided automatically by the provider annotation.
Inspect parameter values and troubleshoot failures
TestNG’s HTML reports show the parameters used to invoke test methods. Use the report to distinguish a mapping/configuration problem from a failure in the Selenium flow.
- Parameter not found: Check that the XML name exactly matches the string in
@Parameters. Spelling and capitalization must line up. - Arguments received in the wrong order: Compare the order in
@Parameterswith the Java method signature. TestNG maps according to the annotation order. - Unexpected value despite a suite setting: Check for an override at test, class, or methods scope; narrower scopes take precedence.
- Missing parameter should be acceptable: Add
@Optional("default")to that method argument. If absence should be an error, do not hide it with a default. - Provider name not found: Ensure
@Test(dataProvider = "...")matches@DataProvider(name = "..."). If the provider is in another class, specify the correctdataProviderClass. - Provider arguments do not fit the test: Check that every row has the expected number and order of values for the test method signature.
- Intermittent failures only when parallel: Remove shared WebDriver or mutable data state, isolate each invocation, and confirm teardown quits the invocation’s own driver.
- Wrong browser or navigation fails: Confirm the received parameter in the TestNG report, then check that your driver factory supports that browser and that the supplied URL is the intended environment.
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Frequently Asked Questions
Can I use @Parameters and @DataProvider in the same TestNG project?
Yes. Use XML parameters for shared run configuration and a data provider for per-invocation test cases; keep those responsibilities distinct.
Where can I see the arguments TestNG passed to a test?
TestNG’s generated HTML reports show the parameters used to invoke test methods.
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