tests: add support for SCL-ized LLVM 13 (llvm-toolset-13.0)

tests/build-gating.fmf

@@ -1,3 +1,15 @@
+#
+# Build/PR gating tests for *LLVM 13*
+#
+# Compatible with various LLVM 13 distributions:
+#
+#   * Fedora (ursine packages)
+#   * Centos 9 stream (ursine packages)
+#   * RHEL-9 (ursine packages)
+#   * RHEL-8 (Red Hat module)
+#   * RHEL-7 (software collection)
+#
+
 summary: compiler-rt tests for build/PR gating
 adjust:
   - because: "Plan to be ran when either executed locally, or executed by CI system to gate a build or PR."
@@ -6,16 +18,18 @@ adjust:
       and trigger != commit
       and trigger != build
     enabled: false
+
+  - because: "When testing SCL-ized LLVM, the collection must be enabled first"
+    environment+:
+      WITH_SCL: "scl enable llvm-toolset-13.0 rust-toolset-1.58"
+    when: "collection == llvm-toolset-13.0"
+
 discover:
     - name: python-lit-tests
       how: fmf
       filter: "tag:-spoils-installation"
 execute:
     how: tmt
-prepare:
-    - name: packages
-      how: install
-      package: python3-lit
 provision:
   hardware:
     memory: ">= 4 GiB"

tests/sanity/main.fmf

@@ -1,4 +1,13 @@
 summary: Trivial sanity test
-test: lit --version
-require:
-  - python3-lit
+test: "$WITH_SCL ./test.sh"
+require: []
+adjust:
+  # Common requirements when LLVM is not SCL-ized
+  - require+:
+      - python3-lit
+    when: "collection is not defined"
+
+  # Requirements for SCL-ized LLVM
+  - require+:
+      - llvm-toolset-13.0-python3-lit
+    when: "collection == llvm-toolset-13.0"

tests/sanity/test.sh

@@ -0,0 +1,3 @@
+#! /bin/sh -eux
+
+lit --version