public void VisitBox()
{
var expression = ExpressionTreeObjectMother.GetSomeBoxAndCastExpression();
Assert.That(expression.Type, Is.Not.SameAs(expression.Operand.Type));
_childExpressionEmitterMock.Setup(mock => mock.EmitChildExpression(expression.Operand)).Verifiable();
_ilGeneratorMock.Setup(mock => mock.Emit(OpCodes.Box, expression.Operand.Type)).Verifiable();
_ilGeneratorMock.Setup(mock => mock.Emit(OpCodes.Castclass, expression.Type)).Verifiable();
var result = _emitter.VisitBox(expression);
_childExpressionEmitterMock.Verify();
_ilGeneratorMock.Verify();
Assert.That(result, Is.SameAs(expression));
}