Folder discovery: skip CI-matrix-only group alias sections

Project.toml

@@ -1,7 +1,7 @@
 name = "SciMLTesting"
 uuid = "09d9d899-5365-40a9-917a-5f67fddea283"
 authors = ["SciML"]
-version = "2.1.0"
+version = "2.2.0"
 
 [deps]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"

src/SciMLTesting.jl

@@ -109,6 +109,12 @@ options. Recognized per-group options:
     explicitly to `false` for documentation/clarity). Set `in_all = false` on any
     heavy or environment-specific group to curate `"All"`. The reserved `"Everything"`
     group ignores `in_all` and runs every declared group (including `"QA"`).
+  * `group` (`String`) — marks the section as a CI-matrix-only *alias* for the named
+    group: it runs that group's body under a different matrix cell (e.g. a 32-bit lane
+    `["Core 32-bit"] group = "Core"` that the CI matrix runs with `arch = "x86"`) and
+    has no test folder of its own. Folder-discovery mode skips such a section under
+    `"All"`/`"Everything"` (the target group already runs) and, if it is selected by
+    its own name, runs the target group rather than demanding a `test/<section>/` folder.
 
 The returned dict preserves declaration order (insertion-ordered), and group names
 are returned verbatim (SciML group names are capitalized: `Core`, `QA`, `Interface`,
@@ -155,6 +161,16 @@ end
 _group_in_all(name::AbstractString, opts::AbstractDict) =
     name != "QA" && get(opts, "in_all", true) == true
 
+# A test_groups.toml section with a `group` key pointing at another group is a
+# CI-matrix-only alias: it runs that group's body under a different arch/os cell
+# (e.g. a 32-bit lane `["Core 32-bit"] group = "Core" arch = "x86"`) and has no
+# test folder of its own. The CI matrix dispatches GROUP=<target>, so such a
+# section is never selected by its own name in practice; folder discovery skips
+# it under All/Everything (the target group already runs) and, if it is selected
+# directly, redirects to the target rather than demanding a `test/<section>/` folder.
+_group_alias_target(name::AbstractString, opts::AbstractDict) =
+    (g = get(opts, "group", nothing); (g isa AbstractString && g != name) ? g : nothing)
+
 # Resolve a group name to its folder under `test_dir`, trying an exact match first
 # then a case-insensitive match (so group "Interface" finds test/Interface or
 # test/interface, and "QA" finds test/qa or test/QA). Returns the absolute folder
@@ -1284,6 +1300,7 @@ function _run_folder_group(
         # top-level Core run above and not re-run as a folder.
         for name in sort!(collect(keys(group_table)))
             name in ("Core", "QA") && continue
+            _group_alias_target(name, group_table[name]) === nothing || continue
             _group_in_all(name, group_table[name]) || continue
             _run_group_folder(test_dir, name, default_parent)
         end
@@ -1295,6 +1312,7 @@ function _run_folder_group(
         _run_core_folder(test_dir)
         for name in sort!(collect(keys(group_table)))
             name == "Core" && continue
+            _group_alias_target(name, group_table[name]) === nothing || continue
             _run_group_folder(test_dir, name, default_parent)
         end
         return nothing
@@ -1307,7 +1325,14 @@ function _run_folder_group(
         _run_group_folder(test_dir, "QA", default_parent)
         return nothing
     elseif haskey(group_table, group)
-        _run_group_folder(test_dir, group, default_parent)
+        # A matrix-only alias section selected by its own name runs the target
+        # group's body rather than demanding a `test/<section>/` folder.
+        target = _group_alias_target(group, group_table[group])
+        if target !== nothing
+            _run_folder_group(target, test_dir, group_table, default_parent)
+        else
+            _run_group_folder(test_dir, group, default_parent)
+        end
         return nothing
     else
         # An unknown group in folder mode is an error rather than a silent Core

test/runtests.jl

@@ -1763,6 +1763,58 @@ end
         @test ran("core") && ran("Light") && ran("Heavy") && ran("QA")
     end
 
+    @testset "run_tests folder mode: matrix-only `group` alias section demands no folder" begin
+        # A section with a `group` key (e.g. a 32-bit CI lane `["Core 32-bit"]
+        # group = "Core"`) is a matrix-only alias for another group's body. It has
+        # no test folder, so All/Everything must SKIP it (not throw "folder missing"),
+        # and selecting it by name runs the target group.
+        tdir = mktempdir()
+        write(
+            joinpath(tdir, "test_groups.toml"),
+            """
+            ["Core 32-bit"]
+            group = "Core"
+            arch = "x86"
+            [Light]
+            """,
+        )
+        markerfile(rel, name) = "write(joinpath(@__DIR__, \"$(rel)ran_$(name)\"), \"1\")\n"
+        write(
+            joinpath(tdir, "core.jl"),
+            "@testset \"core\" begin @test true end\n" * markerfile("", "core"),
+        )
+        ld = joinpath(tdir, "Light"); mkpath(ld)
+        write(
+            joinpath(ld, "l.jl"),
+            "@testset \"l\" begin @test true end\n" * markerfile("../", "Light"),
+        )
+        ran(n) = isfile(joinpath(tdir, "ran_$(n)"))
+        clear() = for n in ("core", "Light")
+            isfile(joinpath(tdir, "ran_$(n)")) && rm(joinpath(tdir, "ran_$(n)"))
+        end
+
+        # All: the alias section is skipped — no `test/Core 32-bit/` folder is
+        # demanded (previously this threw ArgumentError), Core + Light still run.
+        withenv("GROUP" => "All") do
+            run_tests(; test_dir = tdir)
+        end
+        @test ran("core") && ran("Light")
+
+        # Everything: same skip, no throw.
+        clear()
+        withenv("GROUP" => "Everything") do
+            run_tests(; test_dir = tdir)
+        end
+        @test ran("core") && ran("Light")
+
+        # Selecting the alias by name runs the target group's body (Core), not Light.
+        clear()
+        withenv("GROUP" => "Core 32-bit") do
+            run_tests(; test_dir = tdir)
+        end
+        @test ran("core") && !ran("Light")
+    end
+
     @testset "run_tests folder mode: non-group subfolder (shared/) is ignored" begin
         # A subfolder that is NOT a declared group (test/shared/) is never discovered.
         # It is where shared include/fixture files live. Selecting any group must not