Methods

Use mock.SetupMock.Method.MethodName(…) to set up methods. You can specify argument matchers for each parameter.

Returns / Throws

Use .Returns(…) to specify the value to return. You can provide a direct value, a callback, or a callback with parameters. Use .Throws(…) to specify an exception to throw. Supports direct exceptions, exception factories, or factories with parameters.

You can call .Returns(…) and .Throws(…) multiple times to define a sequence of return values or exceptions (cycled on each call).

// Setup Dispense to decrease stock and raise event
sut.SetupMock.Method.Dispense(It.Is("Dark"), It.IsAny<int>())
    .Returns((type, amount) =>
    {
        var current = sut[type];
        if (current >= amount)
        {
            sut[type] = current - amount;
            sut.RaiseOnMock.ChocolateDispensed(type, amount);
            return true;
        }
        return false;
    });

// Setup method to throw
sut.SetupMock.Method.Dispense(It.Is("Green"), It.IsAny<int>())
    .Throws<InvalidChocolateException>();

// Sequence of returns and throws
sut.SetupMock.Method.Dispense(It.IsAny<string>(), It.IsAny<int>())
    .Returns(true)
    .Throws(new Exception("Error"))
    .Returns(false);

Async Methods

For async methods returning Task/Task<T> or ValueTask/ValueTask<T>, use .ReturnsAsync(…) or ThrowsAsync(…) respectively:

sut.SetupMock.Method.DispenseAsync(It.IsAny<string>(), It.IsAny<int>())
    .ReturnsAsync((_, v) => v)            // First execution returns the value of the `int` parameter
    .ThrowsAsync(new TimeoutException())  // Second execution throws a TimeoutException
    .ReturnsAsync(0).Forever();           // Subsequent executions return 0

Callbacks

Use .Do(…) to run code when the method is called. Supports parameterless or parameter callbacks.

// Setup method with callback
sut.SetupMock.Method.Dispense(It.Is("White"), It.IsAny<int>())
    .Do((type, amount) => Console.WriteLine($"Dispensed {amount} {type} chocolate."));

Notes:

• Use .SkippingBaseClass(…) to override the base class behavior for a specific method (only for class mocks).
• When you specify overlapping setups, the most recently defined setup takes precedence.
• All callbacks and return values support more advanced features like conditional execution, frequency control, parallel execution, and access to the invocation counter. See Advanced callback features for details.