c# - Adding Virtual Keyword When Testing Legacy Code -

i adding tests gnarly legacy code in order have confidence enough refactor it. 1 of issues whoever wrote code made no attempt make code testable (given never wrote single unit test!)

a common issue there no interfaces, 11-level-deep inheritance chain. using rhino mocks isolate class under test dependencies, mocking class, not interface, can stub read-only property if has virtual keyword.

my current thinking add virtual keyword property. there no plan add further objects existing dependency chain , allow tests written.

are arguments against adding virtual keyword, or acceptable compromise in order tests in?

example code...

in test class:

var someclassstub = mockrepository.generatestub<someclass>(); someclassstub.stub(s => s.someproperty).return("test"); 

in someclass:

public virtual string someproperty {     {         return somedependency.somemethod();     } } 

the primary argument against adding virtual misrepresents intentions. virtual keyword signals derived classes expect property may overridden.

i not use virtual, mock dependency following:

var mockeddependency = mockrepository.generatemock<idependency>(); mockeddependency.expect(x => x.somemethod())                 .returns("whatever test dictates");  var target = new someclass(mockeddependency);  mockeddependency.verifyallexpectations(); 

then inject newly created overloaded constructor, following:

public someclass(idependency dependency) : base() {     this.somedependency = dependency; }