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# +Goal should_give +CheckGoal

Run the goal Goal and print a message if Goal and CheckGoal don't succeed

## Description

Run the goal Goal and print a message if Goal does not succeed, or if the result doesn't satisfy CheckGoal.

CheckGoal can be an arbitrary user-defined goal. In this case, the first solution of Goal is committed to, and CheckGoal executed with the variable instantiations of this solution.

To allow verification of goals with multiple solutions, one special form of CheckGoal is recognised:

> multiple_solutions(SolCountVar, FinalCheck, SolutionCheck)

where SolCountVar should be a fresh variable. With such a CheckGoal, ALL solutions to Goal will be generated. For each solution, SolutionCheck will be executed with the variable instantiations of this solution, and with SolCountVar instantiated to the number of this solution (starting from 1). After all solutions have been found, FinalCheck will be executed, with SolCountVar instantiated to the total number of solutions.

### Modules

This predicate is sensitive to its module context (tool predicate, see @/2).

## Examples

        % Testing deterministic goals

        X is 3.0+4 should_give X=7.0.

        T1=foo(_,_), copy_term(T1,T2) should_give variant(T1,T2).

        % Testing nondeterministic goals

        member(X,[a,b,c]) should_give multiple_solutions(K, K==3,
            ( K==1 -> X==a
            ; K==2 -> X==b
            ; K==3 -> X==c
    	)).

## See Also

should_fail / 1, should_throw / 2, should_raise / 2, should_give / 3, should_fail / 2, should_throw / 3, should_raise / 3