# Tests $10$ points: Simple tests for AND nodes.

s $=$ AND$\_$OR$\_$Scheduler$()$

s$.$add$\_$and$\_$task$(\text{'}$a$\text{'},[\text{'}$b$\text{'},\text{'}$c$\text{'}])$

assert s$.$available$\_$tasks $==\{\text{'}$b$\text{'},\text{'}$c$\text{'}\}$

r $=$ s$.$mark$\_$completed$(\text{'}$b$\text{'})$

assert r $==$ set$()$

assert s$.$available$\_$tasks $==\{\text{'}$c$\text{'}\}$

r $=$ s$.$mark$\_$completed$(\text{'}$c$\text{'})$

assert r $==\{\text{'}$a$\text{'}\}$

assert s$.$available$\_$tasks $==\{\text{'}$a$\text{'}\}$

r $=$ s$.$mark$\_$completed$(\text{'}$a$\text{'})$

assert r $==$ set$()$

assert s$.$available$\_$tasks $==$ set$()$