public void FileSystem_ArpCommandPath_FileExists_OSX()
{
Mock <IOperatingSystem> operatingSystemMock = new Mock <IOperatingSystem>();
operatingSystemMock.Setup(osm => osm.IsWindows()).Returns(false);
operatingSystemMock.Setup(osm => osm.IsOsx()).Returns(true);
var fileSystem = new FileSystem(typeof(FileSystemIntegrationTests), operatingSystemMock.Object);
fileSystem.ArpCommandPath().Should().Be("/usr/sbin/arp");
}