Assign BoundaryStyle to more than one region in Region Plot using a theme

Question

Consider the minimal example

RegionPlot[{x^2 < y^3 + 1, y^2 < x^3 + 1}, {x, -2, 5}, {y, -2, 5}]

Then I can use

PlotStyle -> {Red, Yellow}
BoundaryStyle -> {1 -> Green, 2 -> Blue}

to, for example, set the red and yellow the first and second region, respectively. And also turn the boundaries green and blue in the same order.

The problem arises when I try to promote this change to a theme

Themes`AddThemeRules["test",
  PlotStyle -> {Red, Yellow},
  BoundaryStyle -> {1 -> Green, 2 -> Blue}
  ];

Now applying this theme PlotTheme->"test" doesn't seem to work but in particular it turns all the boundaries black and thin.

Any thoughts on how to make this work? I prefer working with themes or something similar to keep my code cleaner.

Answer 1

System`PlotThemeDump`resolvePlotTheme["Default", "RegionPlot"]

You can customize the default theme of RegionPlot by changing the above output and name it as new theme "test" by the following code.

System`PlotThemeDump`resolvePlotTheme["test", p : "RegionPlot"] := 
 System`PlotThemeDump`resolvePlotTheme["Default", 
   "RegionPlot"] /. {("DefaultBoundaryColor" -> _) -> 
    "DefaultBoundaryColor" -> {1 -> Green, 
      2 -> Blue}, ("DefaultColor" -> _) -> 
    "DefaultColor" -> {1 -> Red, 2 -> Yellow}}

---

RegionPlot[{x^2 < y^3 + 1, y^2 < x^3 + 1}, {x, -2, 5}, {y, -2, 5}, 
 PlotTheme -> "test"]