Add assert_is_solved_and_feasible

[odow]

Closes #3923

Bikeshedding: the alternative is is_solved_and_feasible(model; assert = true)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.58%. Comparing base (6e4427a) to head (90757eb).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3925   +/-   ##
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  Coverage   99.58%   99.58%           
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  Files          43       43           
  Lines        6059     6063    +4     
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+ Hits         6034     6038    +4     
  Misses         25       25           

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[mlubin]

I like it.

[odow]

It's too late now, but for JuMP 2.0, a better solution might be for this to be the default behavior of optimize!(model), and you have to explicitly pass something optimize!(model; skip_status_check = true) which is a sign that you will then explicitly check the problem statuses before querying the solution.

Right now we have the behavior that almost everyone should use

optimize!(model)
assert_is_solved_and_feasible(model)

and some people should do

optimize!(model)
if termination_status(model) == OPTIMAL
    # ...
else if termination_status(model) == TIME_LIMIT
    # ...
else
    # ...
end

[odow]

Thoughts on new function instead of a keyword?

[blegat]

This is something to be used in quick scripts so keystrokes matter. assert_is_solved_and_feasible will be easier to type, auto-complete etc... It also makes sense as another function since the behavior is quite different, I don't see it just as finetuning of is_solved_and_feasible

[odow]

Okay. This is good to go by me then.