Test methods have names like  testFoo
Test results are verified by assertEquals()
A simple test for addition:
  public void testAdd() {
 
    Complex z1 = new Complex(1, 1);
    Complex z2 = new Complex(1, 1);
    Complex z3 = z1.add(z2);
    assertEquals(2, z3.getRealPart());
    assertEquals(2, z3.getImaginaryPart());
  
  }Let's look at this in Eclipse