How do I write a FsCheck generator for an interface in C#

Question

Suppose I have an interface IPerson with 2 read properties age (int) and name (string).

I also have a class Person implementing IPerson.

How do I write a FsCheck generator for generating instances of IPerson type?

I mean generator in the FsCheck meaning: https://fscheck.github.io/FsCheck/TestData.html — sthiers, Feb 05 '16 at 09:15
Don't quite understand why this downvoted or being closed as unclear. It's a reasonably clear question unless you don't know what FsCheck is, but in that case just move along, nothing to see here. — Kurt Schelfthout, Feb 05 '16 at 15:52

score 8 · Accepted Answer · answered Feb 05 '16 at 15:50

8

Something like the below should work:

Gen<IPerson> gen = from age in Arb.Default.Int32().Generator
                   from name in Arb.Default.String().Generator
                   select new Person(age, name) as IPerson;

answered Feb 05 '16 at 15:50

Kurt Schelfthout

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It works, indeed. But how can you use the "from" clause on Arb.Default.Int32().Generator, as IGen does not implement IEnumerable. What 's the magic? – sthiers Feb 09 '16 at 14:10
LINQ syntax works on any type that implements certain methods (Select, SelectMany, GroupBy etc), not just IEnumerable. Gen implements some of those. – Kurt Schelfthout Feb 17 '16 at 14:17

How do I write a FsCheck generator for an interface in C#

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