Wrap test files in modules

Author: serenity4

test/benchmark.jl

@@ -1,3 +1,5 @@
+module _benchmark
+
 using Pkg; Pkg.activate(joinpath(dirname(@__DIR__), "benchmark"))
 using DAECompiler
 using DAECompiler: compute_residual_vectors
@@ -22,3 +24,5 @@ end
 let sol = solve(DAECProblem(Benchmark{3}(), [1:9;] .=> 0.), IDA())
     @test_broken sol.retcode == ReturnCode.Success
 end
+
+end # module _benchmark

test/validation.jl

@@ -1,3 +1,5 @@
+module _validation
+
 using DAECompiler
 using DAECompiler: refresh, compute_residual_vectors
 
@@ -235,3 +237,5 @@ end
         @test residuals ≈ expanded_residuals
     end
 end;
+
+end # module _validation