DuckTest is a program that attempts to type-check Python source files by using type inference on Python structural types.

It is named after the famous (or maybe infamous) 'duck test'. That is, "if it looks, walks and quacks like a duck, then it must be a duck." DuckTest uses type inference on aspects of python programs (given that the programs are sanely typed) to look for inconsistencies in typing. In short, DuckTest does exactly what its name says, it checks to see if your source code passes the Duck Test.

For best results, DuckTest should be run on Python programs that intend to adhere to Type Erasure Semantics. This means that the program should not dynamically introspect the types at runtime and branch based on them. This means no branching on the __class__ attribute, or any other type-level attribute. Failure to adhere to this rule will result in some false positives.