Include tree tests (#950)

Author: felixcremer

test/runtests.jl

@@ -22,6 +22,7 @@ end
 
 @time @safetestset "array" begin include("array.jl") end
 @time @safetestset "stack" begin include("stack.jl") end
+@time @safetestset "tree" begin include("tree.jl") end
 @time @safetestset "indexing" begin include("indexing.jl") end
 @time @safetestset "methods" begin include("methods.jl") end
 @time @safetestset "broadcast" begin include("broadcast.jl") end