What steps will reproduce the problem? 1. I have a class whose constructor looks like this: public FtpClient(int ftpTimeout, string ftpAddress, int ftpPort, string ftpDropFolder, string ftpUser, string ftpPassword) { ... } 2. Mocking it like this works just fine: new Mock<FtpClient>(1, "", 0, "", "", "").Object; 3. This throws a 'matching constructor... not found' exception: new Mock<FtpClient>(0, "", 0, "", "", "").Object;

What is the expected output? What do you see instead? I expected the second example to behave just like the first (Items 2 and 3 above). Instead, passing zero instead of anything non-zero as the first parameter caused an exception (even though passing a zero as the next int is just fine.)

What version of the product are you using? On what operating system? 3.1.416.3. Windows 7.

Please provide any additional information below. (Thank you!)

I can also duplicate the problem with a constructor that just takes a single int.

I stepped through the source, and it is picking the constructor for Mock that takes the MockBehavior as the first arg, followed by the params object[] (implicitly casting the zero to MockBehavior, apparently, but not 1).