Add setup.Verifiable(Times times, [string failMessage]) method

[stakx]

Better late than never. 😁

Usage summary:

1. Specifying a maximum number of allowed calls:

var bomb = new Mock<IBomb>();
bomb.Setup(b => b.Poke()).Verifiable(Times.AtMostOnce);
bomb.Object.Poke();
bomb.Object.Poke();  // throws `MockException` right away, without an explicit `mock.Verify()`

(This is mostly equivalent to the deprecated setup.AtMostOnce() and setup.AtMost(n) methods, except those didn't mark a setup as verifiable.)

2. Using mock.Verify[All]() to check whether the setup was called the correct number of times:

var bomb = new Mock<IBomb>();
bomb.Setup(b => b.Poke()).Verifiable(Times.Never);
bomb.Verify();  // passes

3. Excluding a setup from mock.VerifyAll() using (e.g.) Times.AtMost(int.MaxValue):

var anyNumberOfTimes = Times.AtMost(int.MaxValue);
var bomb = new Mock<IBomb>();
bomb.Setup(b => b.Poke()).Verifiable(anyNumberOfTimes);
bomb.Object.Poke();
bomb.VerifyAll();  // passes, even if the above line of code were removed

(It would be nicer to have something like Times.Any, however that wouldn't make sense in most scenarios and might confuse users into doing strange things, so I chose not to add that to the library for now.)

4. Verifying the number of calls in situations where invocation arguments are modified after the invocation (but before verification) happened:

 var product = new Product();
 var inventory = new Mock<IInventory>();
+inventory.Setup(a => a.Add(It.Is<Product>(p => p.Type == "Flower"))).Verifiable(Times.Once);

 product.Type = "Flower";
 inventory.Object.Add(product);
 product.Type = "Bomb";

-inventory.Verify(i => i.Add(It.Is<Product>(p => p.Type == "Flower")), Times.Once);  // fails because product is now a bomb
+inventory.Verify();  // works because the setup triggered when product was still a flower

Closes #373, closes #937, closes #1210.

[rishisolutionsbysms]

When this is going to released?

[stakx]

I'd love to do a release but I'm currently blocked from doing so by #1340.

[andy1547]

This feature has been monumental in allowing us to migrate from NMock to Moq without rewriting 3000+ tests to the AAA style. @stakx We'd be incredibly grateful if you could create a new release :')

[stakx]

@andy1547, sorry for not replying earlier, I've been somewhat busy with my daytime life lately. Fortunately, @kzu has in the meantime cleared the road-blocks that have prevented us from doing releases.