How to write a test case for a method returning ob

问题:

I have a method for which the return type is object. How do I create a test case for this? How do I mention that the result should be an object?

e.g.:

public Expression getFilter(String expo)
{
    // do something
    return object;
}

回答1:

try Something like this. If the return-type of your function is Object then replace Expression by Object:

//if you are using JUnit4 add in the @Test annotation, JUnit3 works without it.
//@Test
public void testGetFilter(){
    try{
        Expression myReturnedObject = getFilter("testString");
        assertNotNull(myReturnedObject);//check if the object is != null
        //checks if the returned object is of class Expression
        assertTrue( true, myReturnedObject instaceof Expression);
    }catch(Exception e){
        // let the test fail, if your function throws an Exception.
        fail("got Exception, i want an Expression");
     }
}

回答2:

In your example the returntype is Expression? I don't understand the question, could you elaborate?

The function is even unable to return anything other than Expression (or a derived type or null). So "checking the type" would be pointless.

[TestMethod()]
public void FooTest()
{
    MyFoo target = new MyFoo();
    Expression actual = target.getFilter();

    Assert.IsNotNull(actual);  //Checks for null
    Assert.IsInstanceOfType(actual, typeof(Expression)); //Ensures type is Expression
}

I am assuming C# here; you haven't tagged your question nor mentioned the language in your question.