TestNG 非静态数据提供者方法不起作用

Question

I have a test class and test method. This depends on data provider method. The data provider method is in different class other than the test class or one of its base classes. As per TestNG documentation

If you want to put your data provider in a different class, it needs to be a static method or a class with a non-arg constructor, and you specify the class where it can be found in the dataProviderClass attribute

Test class:

package test;

import org.testng.Assert;
import org.testng.annotations.Test;

import dataprovider.TestDataProvider;

public class TestClass {
      @Test(dataProvider = "get", dataProviderClass=TestDataProvider.class)
      public void test1(String s1, String s2) {
          Assert.assertEquals(s1.length(), s2.length());
      }
}

Data provider class:

package dataprovider;

import org.testng.annotations.DataProvider;

public class TestDataProvider {
    @DataProvider(name = "get")
    public Object[][] testData() {
        return new Object[][] {{"a", "b"},{"c", "d"}};
    }
}

Test Output from Eclipse:

    java.lang.RuntimeException: Can't invoke method public java.lang.Object[][] dataprovider.
TestDataProvider.testData() on this instance of class test.TestClass due to class mismatch
    at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:75)
    at org.testng.internal.MethodInvocationHelper.invokeDataProvider(MethodInvocationHelper.java:137)
    at org.testng.internal.Parameters.handleParameters(Parameters.java:430)
    at org.testng.internal.Invoker.handleParameters(Invoker.java:1243)
    at org.testng.internal.Invoker.createParameters(Invoker.java:992)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1082)
    at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:129)
    at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:112)
    at org.testng.TestRunner.privateRun(TestRunner.java:778)
    at org.testng.TestRunner.run(TestRunner.java:632)
    at org.testng.SuiteRunner.runTest(SuiteRunner.java:366)
    at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:361)
    at org.testng.SuiteRunner.privateRun(SuiteRunner.java:319)
    at org.testng.SuiteRunner.run(SuiteRunner.java:268)
    at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
    at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
    at org.testng.TestNG.runSuitesSequentially(TestNG.java:1225)
    at org.testng.TestNG.runSuitesLocally(TestNG.java:1150)
    at org.testng.TestNG.runSuites(TestNG.java:1075)
    at org.testng.TestNG.run(TestNG.java:1047)
    at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:126)
    at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:137)
    at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:58)

It seems it's not working. I am using TestNG 6.9.11 and tried running from maven as well as from eclipse. I am using latest Eclipse-TestNG plugin.

Answer 1

Disclaimer: I'm the one who added the support of non static methods from external dataProvider .

Just add @Guice on your class:

@Guice
public class TestClass {
    @Test(dataProvider = "get", dataProviderClass=TestDataProvider.class)
    public void test1(String s1, String s2) {
        Assert.assertEquals(s1.length(), s2.length());
    }
}

It is a not yet referenced issue.

Answer 2

Already you have answered your question that,

If you want to put your data provider in a different class, it needs to be a static method or a class with a non-arg constructor.

And as per Java Design It should not work, cause to invoke method from other class either that method should be static or we need object of that class.

testData method is not static, so it cant be invoke using class, and you are not creating non-arg constructor,so not able to create object (without object non-static method could not be invoke).

Hope, you understand my point and you get your answer :)

Answer 3

1. TestNG first looks for data provider in the same class. Eg:

public class DummyTest {

  @DataProvider(name = "data")
  public Object[][] dummyData() {
      return new Object[][]{
              {"Khan"}, {"Kapoor"}
      };
  }

  @Test(dataProvider = "data")
  public void dataProviderTest(String name){
      System.out.println("My Name is " + name);
  }

2. If dataprovider is not found in the same class then TestNG looks in the base class. Eg:

public class DummyData {

    @DataProvider(name = "data")
    public Object[][] dummyData() {
        return new Object[][]{
                {"Khan"}, {"Kapoor"}
        };
    }
}
public class DummyTest extends DummyData {
    @Test(dataProvider = "data")
    public void dataProviderTest(String name){
        System.out.println("My Name is " + name);
    }
}

3. If your DataProvider has default or no-argument constructor, you can declare data provider methods either static or non-static. Eg

public class DummyData {

    @DataProvider(name = "data")
    public Object[][] dummyData() {
        return new Object[][]{
                {"Khan"}, {"Kapoor"}
        };
    }
}
public class DummyTest {
    @Test(dataProvider = "data", dataProviderClass = DummyData.class)
    public void dataProviderTest(String name){
        System.out.println("My Name is " + name);
    }
}

4. If DataProvider class has parameterised constructors, declare dataprovider methods as static othwerwise jvm will throw error. Error snapshot from intellij:

objc[48034]: Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/bin/java (0x1037f04c0) and /Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/jre/lib/libinstrument.dylib (0x1038b84e0). One of the two will be used. Which one is undefined.
[Utils] [ERROR] [Error] java.lang.InstantiationException: apitestset.users.DummyData
    at java.lang.Class.newInstance(Class.java:427)
    at org.testng.internal.ClassHelper.newInstance(ClassHelper.java:69)
    at org.testng.internal.Parameters.findDataProvider(Parameters.java:582)
    at org.testng.internal.Parameters.findDataProvider(Parameters.java:509)
    at org.testng.internal.Parameters.handleParameters(Parameters.java:691)
    at org.testng.internal.ParameterHandler.handleParameters(ParameterHandler.java:49)
    at org.testng.internal.ParameterHandler.createParameters(ParameterHandler.java:37)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:924)
    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.IDEARemoteTestNG.run(IDEARemoteTestNG.java:72)
    at org.testng.RemoteTestNGStarter.main(RemoteTestNGStarter.java:127)
Caused by: java.lang.NoSuchMethodException: apitestset.users.DummyData.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.newInstance(Class.java:412)
    ... 23 more


org.testng.TestNGException: 
Cannot instantiate class apitestset.users.DummyData

    at org.testng.internal.ClassHelper.newInstance(ClassHelper.java:71)
    at org.testng.internal.Parameters.findDataProvider(Parameters.java:582)
    at org.testng.internal.Parameters.findDataProvider(Parameters.java:509)
    at org.testng.internal.Parameters.handleParameters(Parameters.java:691)
    at org.testng.internal.ParameterHandler.handleParameters(ParameterHandler.java:49)
    at org.testng.internal.ParameterHandler.createParameters(ParameterHandler.java:37)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:924)
    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.IDEARemoteTestNG.run(IDEARemoteTestNG.java:72)
    at org.testng.RemoteTestNGStarter.main(RemoteTestNGStarter.java:127)
Caused by: java.lang.InstantiationException: apitestset.users.DummyData
    at java.lang.Class.newInstance(Class.java:427)
    at org.testng.internal.ClassHelper.newInstance(ClassHelper.java:69)
    ... 22 more
Caused by: java.lang.NoSuchMethodException: apitestset.users.DummyData.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.newInstance(Class.java:412)
    ... 23 more

Answer 4

For other people who are receiving the same error, but haven't able to fix them following other answers:

I noticed this error started appearing for me after upgrading my TestNG plugin from 6.X to 7.0 within Eclipse. I tried following the other solutions, but the only thing that ended up working for me was completely uninstalling TestNG (plugin, TestNg Maven, etc) and then setting the update site to that specific version of TestNG.

Answer 5

It was broken between 6.8.x and 6.10.x. Using any version other than within that range should fix your problem.