• Getting started
• Creating a substitute
• Setting a return value
• Return for specific args
• Return for any args
• Return from a function
• Multiple return values
• Replacing return values
• Checking received calls
• Clearing received calls
• Argument matchers
• Callbacks, void calls and When..Do
• Throwing exceptions
• Safe configuration and overlapping calls
• Raising events
• Auto and recursive mocks
• Setting out and ref args
• Actions with argument matchers
• Checking call order
• Partial subs and test spies
• Return for all calls of a type
• Threading
• Compatibility argument matchers
• NSubstitute.Analyzers
• How NSubstitute works
• Search

Multiple return values

A call can also be configured to return a different value over multiple calls. The following example shows this for a call to a property, but it works the same way for method calls.

calculator.Mode.Returns("DEC", "HEX", "BIN");
Assert.AreEqual("DEC", calculator.Mode);
Assert.AreEqual("HEX", calculator.Mode);
Assert.AreEqual("BIN", calculator.Mode);

This can also be achieved by returning from a function, but passing multiple values to Returns() is simpler and reads better.

Multiple returns using callbacks

Returns() also supports passing multiple functions to return from, which allows one call in a sequence to throw an exception or perform some other action.

calculator.Mode.Returns(x => "DEC", x => "HEX", x => { throw new Exception(); });
Assert.AreEqual("DEC", calculator.Mode);
Assert.AreEqual("HEX", calculator.Mode);
Assert.Throws<Exception>(() => { var result = calculator.Mode; });

Configuring other calls without using up multiple returns

If a call has been configured with multiple returns values, you can configure a more specific call without using up any of these callbacks using .Configure().