Add support for spy operations.

 






 

 


  Review Request #11153
  —
  Created Aug. 30, 2020 and submitted 

 




















 

  

   Information

  





 
 

  chipx86
 









 
 

  kgb
 









 
 

  master
 









 
 

  
 









 
 

  
 






 




 

  

   Reviewers

  





 
 

  kgb
 









 
 

  
 






 








 





  


 
 

  
A spy operation is an action or set of possible actions that are

performed when a function is called. They're an alternative to

overriding a function explicitly, and instead work as reusable shortcuts

for common patterns used when spying. Examples would be raising an

exception, or dispatching a function based on the arguments provided in

the call.


These can be thought of as glorified functions, and in fact they

basically are, under the hood, but are designed to be extensible so that

projects can more easily maintain common spy patterns.


There are some built-in operations provided by kgb:


    

  • 

    SpyOpMatchAny allows a caller to provide a list of all possible sets
    
  of arguments that may be in one or more calls, triggering spy behavior
    
  for the particular match (allowing call_original/call_fake to be
    
  conditional on the arguments). Any call not provided in the list will
    
  raise an UnexpectedCallError assertion.
    

    • 

  • 

    SpyOpMatchInOrder is similar to SpyOpMatchAny, but the calls
    
  must be in the order specified (which is useful for ensuring an order
    
  of operations).
    

    • 

  • 

    SpyOpRaise takes an exception instance and raises it when the
    
  function is called (preventing a caller from having to define a
    
  wrapping function).
    

    • 

  • 

    SpyOpReturn takes a return value and returns it when the function is
    
  called (similar to defining a simple lambda, but better specifying the
    
  intent).
    

    • 



These are set with an op= argument, instead of a call_fake=. For

example::


spy_on(pen.emit_poison, op=kgb.SpyOpRaise(PoisonEmptyError()))



Or, for one of the more complex examples:


spy_on(traps.trigger, op=kgb.SpyOpMatchAny([
    {
        'args': ('hallway_lasers',),
        'call_fake': _send_wolves,
    },
    {
        'args': ('trap_tile',),
        'call_fake': _spill_hot_oil,
    },
    {
        'args': ('infrared_camera',),
        'kwargs': {
            'sector': 'underground_passage',
        },
        'call_original': False,
    },
]))


 








  


 
 

  
Unit tests pass on all supported versions of Python.


Plugged each of these operations into some real-world code and made sure

they worked as expected.

 







 









 





  

 


 
 

  



 

  
   


    Summary
    ID

   

  
  

   


    

     

      Add support for spy operations.
      
A spy operation is an action or set of possible actions that are
performed when a function is called. They're an alternative to
overriding a function explicitly, and instead work as reusable shortcuts
for common patterns used when spying. Examples would be raising an
exception, or dispatching a function based on the arguments provided in
the call.

These can be thought of as glorified functions, and in fact they
basically are, under the hood, but are designed to be extensible so that
projects can more easily maintain common spy patterns.

There are some built-in operations provided by kgb:

* `SpyOpMatchAny` allows a caller to provide a list of all possible sets
  of arguments that may be in one or more calls, triggering spy behavior
  for the particular match (allowing `call_original`/`call_fake` to be
  conditional on the arguments). Any call not provided in the list will
  raise an `UnexpectedCallError` assertion.

* `SpyOpMatchInOrder` is similar to `SpyOpMatchAny`, but the calls
  must be in the order specified (which is useful for ensuring an order
  of operations).

* `SpyOpRaise` takes an exception instance and raises it when the
  function is called (preventing a caller from having to define a
  wrapping function).

* `SpyOpReturn` takes a return value and returns it when the function is
  called (similar to defining a simple lambda, but better specifying the
  intent).

These are set with an `op=` argument, instead of a `call_fake=`. For
example::

    spy_on(pen.emit_poison, op=kgb.SpyOpRaise(PoisonEmptyError()))

Or, for one of the more complex examples:

    spy_on(traps.trigger, op=kgb.SpyOpMatchAny([
        {
            'args': ('hallway_lasers',),
            'call_fake': _send_wolves,
        },
        {
            'args': ('trap_tile',),
            'call_fake': _spill_hot_oil,
        },
        {
            'args': ('infrared_camera',),
            'kwargs': {
                'sector': 'underground_passage',
            },
            'call_original': False,
        },
    ]))

     


    		
    7222f42482f4d8206ba3258681d01f4dcf543a85

   



  
 




 













 






 
 
 

  

   

    

     
    

    
    
     
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      Description
      From
      Last Updated
     

    
    



     

      
       
       
F401 'kgb.calls.SpyCall' imported but unused

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
E501 line too long (82 > 79 characters)

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F401 'kgb.agency.SpyAgency' imported but unused

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
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F841 local variable 'spy' is assigned to but never used

      		
      
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F841 local variable 'spy' is assigned to but never used

      		
      
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F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
F841 local variable 'spy' is assigned to but never used

      		
      
       reviewbotreviewbot
      
      
       
      
     


    
   

  

 







 






  

 



















 




 

  


   

   

    
 
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flake8

 


 










  

 





 














 



 

  

   




chipx86




   

   

  

 



 















 





 

  

   




david




   

   







  

 



 

  


   

   

    
 
david


    
   


  

  

  



    




  1. 
 
    
  
    
   
    Ship It!
    
  
    
 
    

 
    
  


    
 
    
 
      

  

 
    


    

 
    

    2. 















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chipx86




   

   

  

 



 

  


   

   

    
 Review request changed

    
   


  

  

  






 

  Status:
  

  Closed (submitted)

  
 




 
Change Summary:

 
Pushed to master (743d50e)





 


 










  

 









     

    

   

  

  

   
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