Merge pull request #730 from jonathanfischer97/fix_pop_save

`deepcopy` to save population in default trace, instead of reference

Author: Vaibhavdixit02

lib/OptimizationEvolutionary/src/OptimizationEvolutionary.jl

@@ -18,7 +18,7 @@ function Evolutionary.trace!(tr, iteration, objfun, state, population,
     dt["time"] = curr_time
 
     # record `x` to store the population. Needed for constructing OptimizationState.
-    dt["x"] = population
+    dt["x"] = deepcopy(population)
 
     # set additional trace value
     Evolutionary.trace!(dt, objfun, state, population, method, options)

lib/OptimizationEvolutionary/test/runtests.jl

@@ -50,10 +50,13 @@ Random.seed!(1234)
         record["TESTVAL"] = state.fittest
     end
 
-    #test that `store_trace=true` works now. Threw ""type Array has no field value" before.
+    # Test that `store_trace=true` works now. Threw ""type Array has no field value" before.
     sol = solve(prob, CMAES(μ = 40, λ = 100), store_trace = true)
 
     # Make sure that both the user's trace record value, as well as `x` are stored in the trace.
     @test haskey(sol.original.trace[end].metadata, "TESTVAL") &&
           haskey(sol.original.trace[end].metadata, "x")
+
+    # Test the the values of x are saved, not the reference
+    @test sol.original.trace[end].metadata["x"] !== sol.original.trace[end-1].metadata["x"]
 end