unit testing - A.CallTo method that uses expression as a parameter -

i'm trying this, , doesn't work, although kinda should be

a.callto(() => partyrepo.where(o => o.person != null))                         .returns(new[] {new party()}); 

the call method exact code parameter returns empty enumerable

the reason expression you're passing in call specification , 1 that's sent partyrepo not equal. there's no way fakeiteasy determine if arguments use equals-method.

i'm not sure best workaround, this:

public static class myargumentconstraints {     public static func<myclass, bool> returnstruewhenpersonisnotnull(this iargumentconstraintmanager<func<myclass, bool>> manager)     {         return manager.nullcheckedmatches(x =>                                                 {                                                     return x.invoke(new myclass() {person = "person"}) &&                                                             !x.invoke(new myclass() {person = null});                                                 },                                             x => x.write("predicate returns true non null person"));     } }  public class myclass {     public string person { get; set; } } 

with extension can rewrite original line:

a.callto(() => partyrepo.where(a<func<myclass, bool>>.that.returnstruewhenpersonisnotnull())                     .returns(new[] {new party()});