JUnit Error: Invalid Test Class 'Test.demoTest' - Method 'getIpAddr' Issues

This error message indicates that there are two issues with the 'demoTest' class:

1. The method named 'getIpAddr()' is expected to have a return type of 'void', but it does not.
2. The method named 'getIpAddr' is expected to have no parameters, but it has one or more parameters.

To fix these issues, modify the 'demoTest' class to ensure that the 'getIpAddr()' method has a return type of 'void' and has no parameters.

For example:

public class demoTest {
  @Test
  public void getIpAddr() {
    // test code here
  }
}

In this modified version of the class, the 'getIpAddr()' method has been updated to have a return type of 'void' and no parameters. This should resolve the issues raised by the error message.