Change value of Variable in a method using Reflection

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C#

C#4.0

reflection

Hi All,

How can I change value of a variable of a method when it is invoked using Reflection.

At present below code is updating value of local variable (class level).

Why? : I am writing one Unit Test Case where object of a class might get changed its internal behavior and to test that negative scenario in Unit Test, I want to change value of that variable at runtime like setting an object to Null which sometime returning as null from Database and failing our application.

private void SetVariableValue(BehaviorState behaviorState, string variableName,object value)
{
    Type t = typeof(BehaviorState);


    foreach (var member in t.GetMembers(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public))
    {
        if (member.Name == variableName)
        {
            // changing the variable
            FieldInfo fi = (FieldInfo)member;
            fi.SetValue(behaviorState, value);
            break;
        }

    }
}

Thanks
Rushi