When creating NuGet packages, how do you define your dependencies?
If you're using the default setting of 'x' version or newer are you sure that all future versions of the dependency will work with the current version of your code? I'm not sure many people would be happy saying yes to that question but most NuGet packages are deployed with the default setting for their dependencies. Using a typical dependency, Log4Net, you might deploy a package today referencing the current build and everything's fine. But in a month or two's time there may be an update to Log4Net deployed that contains breaking changes. From that point on anyone that grabs your package from NuGet will find that it no longer works - instead of the version of Log4Net you developed against, they are now getting the latest version that breaks your code.
Whilst it may be more work, the safer option may be to use the version "range" option for managing dependencies; only including versions that have been safely tested and are known to work with your code base. It may be more work, requiring you to retest and update your package each time a dependency is updated but your users will thank you for it.
Since writing this blog post a breaking change has been published to NuGet for the very well used log4Net package. Phil Haacks blog post covers the issue in create detail and I won't attempt to recover it here but it does highlight the risks associated with being fully dependent one or more 3rd parties - your code (and therefore your consumers code) may fail because a dependency has been incorrectly versioned / deployed. In his article Phil also links to an interesting set of posts on how NuGet handles the package versioning.