Testing ASP.NET methods using Nunit

 Hi all,
Need your suggestions

How should i approach testing functions in a ASP.NET application.
Its not integration testing but a unit testing(functions) But the problem is

It is nearly impossible to isolate a function due to dependencies
Many funcition are expecting other objects like Page Class context, Configuration settings many more complex objects like session context... etc

now how can i test this methods using Nunit framework
how should i initialized these objects ?
should i use mock object concept ?
is Nunit framework appropriate tool for writing the test cases ?

Please suggest

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