Test default_stdout_iocontext

Check that each IOContext property is transferred to `stdout` and
`stderr` as seen from inside a notebook

test/StdIOContext.jl

@@ -0,0 +1,23 @@
+using Test
+import Pluto: PlutoRunner, Notebook, WorkspaceManager, Cell, ServerSession, update_run!
+
+@testset "stdout/stderr IOContext" begin
+    🍭 = ServerSession()
+    🍭.options.evaluation.workspace_use_distributed = true
+
+    notebook = Notebook(reduce(
+        vcat,
+        # $(repr(p)) rather than just $p for parseable output, e.g., Symbols with colons
+        [
+            Cell("($(repr(p))) in stdout"),
+            Cell("($(repr(p))) in stderr"),
+        ] for p in pairs(PlutoRunner.default_stdout_iocontext.dict)
+    ))
+
+    update_run!(🍭, notebook, notebook.cells)
+    for cell in values(notebook.cells_dict)
+        @test cell.output.body == "true"
+    end
+
+    WorkspaceManager.unmake_workspace((🍭, notebook))
+end

test/runtests.jl

@@ -24,6 +24,8 @@ verify_no_running_processes()
 verify_no_running_processes()
 @timeit_include("MacroAnalysis.jl")
 verify_no_running_processes()
+@timeit_include("StdIOContext.jl")
+verify_no_running_processes()
 @timeit_include("Logging.jl")
 verify_no_running_processes()
 @timeit_include("webserver.jl")