Hello Folks,
DataProvider is an awesome functionality provided by TestNG to achieve Data Driven Testing. You must have already seen many posts on DataProvider on my blog. If not, I will advise you to go through them.
If you have used DataProvider in your tests, you must have encounter “Data provider mismatch” exception. I see many beginners and experienced professionals struggle at this point as they are not aware of the basic reasons of causing this. So, I would like to explain all possible reasons of occuring this exception here so that it will be helpful to solve when you encounter.
Cause 1: When we do not accept arguments in Test method while using DataProvider with Test Method:-
Base Rule – If you are using a DataProvider with your test, you must need to accept the arguments. It is not OPTIONAL. You must have to accept arguments in your Test Method.
Java Code:
package DataProvider;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
public class DataProviderMismatchCause1 {
// A data provider method with return type as 2D array
@DataProvider(name = "DataContainer")
public static Object[][] myDataProvider() {
return new Object[][] { { "Mukesh", "Otwani", "[email protected]" },
{ "Amod", "Mahajan", "[email protected]" }, { "Animesh", "Prashant", "[email protected]" },
{ "Ankur", "Singh", "[email protected]" }, { "Amritansh", "Kumar", "[email protected]" }
};
}
// Below test method is not accepting any arguments while it has DataProvider.
// You will get Data Provider mismatch exception
@Test(dataProvider = "DataContainer")
public void mismatchDataProvider1() {
System.out.println("Test Method");
}
}
Output:
[java] [RemoteTestNG] detected TestNG version 6.14.2 FAILED: mismatchDataProvider1 org.testng.internal.reflect.MethodMatcherException: Data provider mismatch Method: mismatchDataProvider1([]) Arguments: [(java.lang.String) Mukesh,(java.lang.String) Otwani,(java.lang.String) [email protected]] at org.testng.internal.reflect.DataProviderMethodMatcher.getConformingArguments(DataProviderMethodMatcher.java:45) at org.testng.internal.Parameters.injectParameters(Parameters.java:796) at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:982) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109) at org.testng.TestRunner.privateRun(TestRunner.java:648) at org.testng.TestRunner.run(TestRunner.java:505) at org.testng.SuiteRunner.runTest(SuiteRunner.java:455) at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450) at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415) at org.testng.SuiteRunner.run(SuiteRunner.java:364) at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52) at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84) at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208) at org.testng.TestNG.runSuitesLocally(TestNG.java:1137) at org.testng.TestNG.runSuites(TestNG.java:1049) at org.testng.TestNG.run(TestNG.java:1017) at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114) at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)
=============================================== Default test Tests run: 1, Failures: 1, Skips: 0
===============================================
=============================================== Default suite Total tests run: 1, Failures: 1, Skips: 0
===============================================
[/java]
Cause 2: When we accept less arguments in Test method while using DataProvider with Test Method:-
Base Rule- You must need to accept same number of arguments in your test method as provided by DataProvider method. If your test method returns N arguments in a set, your test method must accept all i.e. N arguments. No More No Less.
Java Code:
package DataProvider;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
public class DataProviderMismatchCause1 {
// A data provider method with return type as 2D array
@DataProvider(name = "DataContainer")
public static Object[][] myDataProvider() {
return new Object[][] { { "Mukesh", "Otwani", "[email protected]" },
{ "Amod", "Mahajan", "[email protected]" }, { "Animesh", "Prashant", "[email protected]" },
{ "Ankur", "Singh", "[email protected]" }, { "Amritansh", "Kumar", "[email protected]" }
};
}
// DataProvider "DataContainer" is passing three arguments but our test method is accepting only two.
// You will get Data Provider mismatch exception
@Test(dataProvider = "DataContainer")
public void mismatchDataProvider1(String FN, String LN) {
System.out.println("Test Method");
}
}
Output:
[java] [RemoteTestNG] detected TestNG version 6.14.2 FAILED: mismatchDataProvider1 org.testng.internal.reflect.MethodMatcherException: Data provider mismatch Method: mismatchDataProvider1([Parameter{index=0, type=java.lang.String, declaredAnnotations=[]}, Parameter{index=1, type=java.lang.String, declaredAnnotations=[]}]) Arguments: [(java.lang.String) Mukesh,(java.lang.String) Otwani,(java.lang.String) [email protected]] at org.testng.internal.reflect.DataProviderMethodMatcher.getConformingArguments(DataProviderMethodMatcher.java:45) at org.testng.internal.Parameters.injectParameters(Parameters.java:796) at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:982) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109) at org.testng.TestRunner.privateRun(TestRunner.java:648) at org.testng.TestRunner.run(TestRunner.java:505) at org.testng.SuiteRunner.runTest(SuiteRunner.java:455) at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450) at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415) at org.testng.SuiteRunner.run(SuiteRunner.java:364) at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52) at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84) at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208) at org.testng.TestNG.runSuitesLocally(TestNG.java:1137) at org.testng.TestNG.runSuites(TestNG.java:1049) at org.testng.TestNG.run(TestNG.java:1017) at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114) at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)
=============================================== Default test Tests run: 1, Failures: 1, Skips: 0
===============================================
=============================================== Default suite Total tests run: 1, Failures: 1, Skips: 0
===============================================
[/java]
Cause 3: When we accept more arguments in Test method while using DataProvider with Test Method:-
Base Rule- You must need to accept same number of arguments in your test method as provided by DataProvider method. If your test method returns N arguments in a set, your test method must accept all i.e. N arguments. No More No Less.
Java Code:
package DataProvider;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
public class DataProviderMismatchCause1 {
// A data provider method with return type as 2D array
@DataProvider(name = "DataContainer")
public static Object[][] myDataProvider() {
return new Object[][] { { "Mukesh", "Otwani", "[email protected]" },
{ "Amod", "Mahajan", "[email protected]" }, { "Animesh", "Prashant", "[email protected]" },
{ "Ankur", "Singh", "[email protected]" }, { "Amritansh", "Kumar", "[email protected]" }
};
}
// DataProvider "DataContainer" is passing three arguments but our test method is accepting four.
// You will get Data Provider mismatch
@Test(dataProvider = "DataContainer")
public void mismatchDataProvider1(String FN, String LN, String emailId, String age) {
System.out.println("Test Method");
}
}
Output:
[java] [RemoteTestNG] detected TestNG version 6.14.2 FAILED: mismatchDataProvider1 org.testng.internal.reflect.MethodMatcherException: Data provider mismatch Method: mismatchDataProvider1([Parameter{index=0, type=java.lang.String, declaredAnnotations=[]}, Parameter{index=1, type=java.lang.String, declaredAnnotations=[]}, Parameter{index=2, type=java.lang.String, declaredAnnotations=[]}, Parameter{index=3, type=java.lang.String, declaredAnnotations=[]}]) Arguments: [(java.lang.String) Mukesh,(java.lang.String) Otwani,(java.lang.String) [email protected]] at org.testng.internal.reflect.DataProviderMethodMatcher.getConformingArguments(DataProviderMethodMatcher.java:45) at org.testng.internal.Parameters.injectParameters(Parameters.java:796) at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:982) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109) at org.testng.TestRunner.privateRun(TestRunner.java:648) at org.testng.TestRunner.run(TestRunner.java:505) at org.testng.SuiteRunner.runTest(SuiteRunner.java:455) at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450) at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415) at org.testng.SuiteRunner.run(SuiteRunner.java:364) at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52) at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84) at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208) at org.testng.TestNG.runSuitesLocally(TestNG.java:1137) at org.testng.TestNG.runSuites(TestNG.java:1049) at org.testng.TestNG.run(TestNG.java:1017) at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114) at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)
=============================================== Default test Tests run: 1, Failures: 1, Skips: 0
===============================================
=============================================== Default suite Total tests run: 1, Failures: 1, Skips: 0
===============================================
[/java]
Cause 4: When we try to downcast the type of arguments provided by DataProvider in our Test method-
Base Rule – Suppose if your DataProvider method is returning an argument of type String, you can accept it as String or its Super class ( E.g. Object). If you try to accept String into Integer etc, You will face Data Provider mismatch exception.
Java Code:
package DataProvider;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
public class DataProviderMismatchCause1 {
// A data provider method with return type as 2D array
@DataProvider(name = "DataContainer")
public static Object[][] myDataProvider() {
return new Object[][] { { "Mukesh", "Otwani", "[email protected]" },
{ "Amod", "Mahajan", "[email protected]" }, { "Animesh", "Prashant", "[email protected]" },
{ "Ankur", "Singh", "[email protected]" }, { "Amritansh", "Kumar", "[email protected]" }
};
}
// Provide incompatible data type
@Test(dataProvider = "DataContainer")
public void mismatchDataProvider1(Integer FN, String LN, String emailId) {
System.out.println("Test Method");
}
}
Output:
[java] [RemoteTestNG] detected TestNG version 6.14.2 FAILED: mismatchDataProvider1 org.testng.internal.reflect.MethodMatcherException: Data provider mismatch Method: mismatchDataProvider1([Parameter{index=0, type=java.lang.Integer, declaredAnnotations=[]}, Parameter{index=1, type=java.lang.String, declaredAnnotations=[]}, Parameter{index=2, type=java.lang.String, declaredAnnotations=[]}]) Arguments: [(java.lang.String) Mukesh,(java.lang.String) Otwani,(java.lang.String) [email protected]] at org.testng.internal.reflect.DataProviderMethodMatcher.getConformingArguments(DataProviderMethodMatcher.java:45) at org.testng.internal.Parameters.injectParameters(Parameters.java:796) at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:982) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109) at org.testng.TestRunner.privateRun(TestRunner.java:648) at org.testng.TestRunner.run(TestRunner.java:505) at org.testng.SuiteRunner.runTest(SuiteRunner.java:455) at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450) at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415) at org.testng.SuiteRunner.run(SuiteRunner.java:364) at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52) at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84) at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208) at org.testng.TestNG.runSuitesLocally(TestNG.java:1137) at org.testng.TestNG.runSuites(TestNG.java:1049) at org.testng.TestNG.run(TestNG.java:1017) at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114) at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)
=============================================== Default test Tests run: 1, Failures: 1, Skips: 0
===============================================
=============================================== Default suite Total tests run: 1, Failures: 1, Skips: 0
===============================================
[/java]
Cause 5: When we use both Parameters and DataProvider in our Test method-
Base Rule- We can not use DataProvider and Parameters together in a Test method.
Java Code:
package DataProvider;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;
public class DataProviderMismatchCause1 {
// A data provider method with return type as 2D array
@DataProvider(name = "DataContainer")
public static Object[][] myDataProvider() {
return new Object[][] { { "Mukesh", "Otwani", "[email protected]" },
{ "Amod", "Mahajan", "[email protected]" }, { "Animesh", "Prashant", "[email protected]" },
{ "Ankur", "Singh", "[email protected]" }, { "Amritansh", "Kumar", "[email protected]" }
};
}
// If we use data provider and parameters both.
// Three parameters from DataProvider and 1 from Parameters annotation.
@Parameters("age")
@Test(dataProvider = "DataContainer")
public void mismatchDataProvider1(String FN, String LN, String emailId, int Age) {
System.out.println("Test Method");
}
}
We need to use testng.xml for this.
[xml]
[/xml]
When you run it, you will get Data Provider mismatch exception.
Hope, you will keep above points in mind while using DataProvider.
If you have any doubt, feel free to comment below. If you like my posts, please like, comment, share and subscribe. #ThanksForReading
#HappySelenium