Check that rpms installed in tmt come from copr

Add a script to ensure that the llvm package installed comes from the
copr repo. A failure in the script aborts the test plan

tests/assert_llvm.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+
+# Script to assert that the llvm rpm installed during tmt prepare steps comes
+# from the copr repo and matches exactly.
+# Rely on dnf4 (/usr/bin/dnf-3) to avoid conflicts in newer Fedoras with dnf5.
+# The script expects $COPR_PROJECT envvar to check the repo.
+if [[ -z $COPR_PROJECT ]]; then
+    echo "*** Missing COPR_PROJECT required environment variable."
+    exit 1
+fi
+
+# Ensure the repo is available
+if ! dnf-3 repolist | grep -q "$COPR_PROJECT"; then
+    echo "*** copr repo $COPR_PROJECT not enabled in dnf"
+fi
+
+assert_package_match (){
+    local pkg=$1
+    local rpm_queryfmt="%{name}-%{version}-%{release}.%{arch}"
+    local installed_pkg pkg_from_copr
+    installed_pkg=$(rpm -q --qf "$rpm_queryfmt" "$pkg"."$(uname -m)")
+    pkg_from_copr=$(dnf-3 -q --disablerepo=* --enablerepo=*"$COPR_PROJECT"* \
+        repoquery --queryformat "$rpm_queryfmt" "$pkg"."$(uname -m)")
+
+    if [[ "$installed_pkg" != "$pkg_from_copr" ]]; then
+        echo "*** Unexpected $pkg package installed: $installed_pkg"
+        echo "*** Expected $pkg: $pkg_from_copr"
+        exit 1
+    fi
+}
+
+for pkg in llvm clang; do
+    assert_package_match "$pkg"
+done

tests/snapshot-gating.fmf

@@ -23,6 +23,11 @@ prepare:
     script: |
       dnf install -y dnf-plugins-core
       dnf config-manager --save --setopt="testing-farm-tag-repository.priority=999" || true
+
+  - name: Assert correct llvm package is installed
+    how: shell
+    order: 99
+    script: tests/assert_llvm.sh
 adjust:
   - discover+:
       - name: redhat-rpm-config-tests