fix cairomakie integration test

Author: jkrumbiegel

test/examples/integrations/CairoMakie.qmd

@@ -16,4 +16,8 @@ import CairoMakie
 
 ```{julia}
 CairoMakie.scatter([1, 2, 3], [1, 2, 3])
+```
+
+```{julia}
+CairoMakie.Makie.current_default_theme()[:CairoMakie][:px_per_unit][]
 ```

test/testsets/integrations/CairoMakie.jl

@@ -3,6 +3,15 @@ include("../../utilities/prelude.jl")
 test_example(joinpath(@__DIR__, "../../examples/integrations/CairoMakie.qmd")) do json
     cells = json["cells"]
     cell = cells[6]
+
+    px_per_inch = 96
+
+    # the size metadata is just inches converted to CSS pixels, independent of pixel resolution
     @test cell["outputs"][1]["metadata"]["image/png"] ==
-          Dict("width" => 4 * 150, "height" => 3 * 150)
+          Dict("width" => 4 * px_per_inch, "height" => 3 * px_per_inch)
+
+    # the pixel resolution is controlled by px_per_unit and that reflects the dpi that is set
+    px_per_unit_str = cells[end-1]["outputs"][1]["data"]["text/plain"]
+    px_per_unit = parse(Float64, px_per_unit_str)
+    @test px_per_unit == 150 / px_per_inch
 end