Test that defaults are not changed

Author: andreasKroepelin

test/runtests.jl

@@ -1,4 +1,5 @@
 using PlotlyLight
+using PlotlyLight.Defaults
 using JSON3
 using Test
 
@@ -12,6 +13,18 @@ using Test
     p(Config(x=1:10,y=rand(10)))
     @test length(p.data) == 2
 end
+#-----------------------------------------------------------------------------# defaults
+@testset "defaults" begin
+    old_layout_default = copy(Defaults.layout[])
+    old_config_default = copy(Defaults.config[])
+    p = Plot()
+    p.layout.xaxis.showgrid = false
+    p.config.editable = true
+    # make sure that mutation of layout and config of one plot has no effect on
+    # global defaults
+    @test Defaults.layout[] == old_layout_default
+    @test Defaults.config[] == old_config_default
+end
 #-----------------------------------------------------------------------------# src
 @testset "src" begin
     p = Plot(Config(y=1:10))