Annotation Type Ensures
Represents a method postcondition.
A postcondition is a condition that is guaranteed to be fulfilled by suppliers.
A method's postcondition is executed after a method call has finished. A successor's postcondition strengthens the postcondition of its parent class, e.g. if A.someMethod declares a postcondition and B.someMethod overrides the method the postconditions are combined with a boolean AND.
Compared to pre-conditions, postcondition annotation closures are optionally called with two additional closure arguments: result and old.
result is available if the corresponding method has a non-void return-type and holds the result of the method call. Be aware that modifying the internal state of a reference type can lead to side-effects. Groovy-contracts does not keep track of any sort of modifications, neither any conversion to immutability.
 old is available in every postcondition. It is a Map which holds the values
 of value types and Cloneable types before the method has been executed.
 
Examples:
Accessing the result closure parameter:
   @Ensures({ result -> result != argument1 })
   def T someOperation(def argument1, def argument2)  {
     ...
   }
 
 Accessing the old closure parameter:
   @Ensures({ old -> old.counter + 1 == counter })
   def T someOperation(def argument1, def argument2)  {
     ...
   }
 
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Required Element SummaryRequired Elements
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Element Details- 
valueClass value
 
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