test: add TestExpectedSeccompVersion

This is to ensure we're testing against the expected libseccomp version
(as prepared by CI, which sets the _EXPECTED_LIBSECCOMP_VERSION var).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

.github/workflows/test.yml

@@ -51,7 +51,11 @@ jobs:
         #  - chances are good such version won't ever exist;
         #  - it is easy to spot in tests output;
         #  - the LIBFILE pattern below expects single digits.
-        sed -i '/^AC_INIT(/s/0\.0\.0/9.9.9/' configure.ac
+        VER="${{ matrix.libseccomp }}"
+        if [ "$VER" == "HEAD" ]; then
+          VER=9.9.9
+          sed -i "/^AC_INIT(/s/0\.0\.0/$VER/" configure.ac
+        fi
         ./autogen.sh
         ./configure --prefix="$PREFIX" --libdir="$LIBDIR"
         make
@@ -63,6 +67,8 @@ jobs:
         echo "PKG_CONFIG_LIBDIR=$LIBDIR/pkgconfig" >> $GITHUB_ENV
         LIBFILE="$(echo $LIBDIR/libseccomp.so.?.?.?)"
         echo "LD_PRELOAD=$LIBFILE" >> $GITHUB_ENV
+        # For TestExpectedSeccompVersion.
+        echo "_EXPECTED_LIBSECCOMP_VERSION=$VER" >> $GITHUB_ENV
 
     - name: build
       run: make check-build

seccomp_test.go

@@ -42,6 +42,27 @@ func execInSubprocess(t *testing.T, f func(t *testing.T)) {
 	}
 }
 
+func TestExpectedSeccompVersion(t *testing.T) {
+	execInSubprocess(t, subprocessExpectedSeccompVersion)
+}
+
+func subprocessExpectedSeccompVersion(t *testing.T) {
+	// This environment variable can be set by CI.
+	const name = "_EXPECTED_LIBSECCOMP_VERSION"
+
+	expVer := os.Getenv(name)
+	if expVer == "" {
+		t.Skip(name, "not set")
+	}
+	expVer = strings.TrimPrefix(expVer, "v")
+
+	curVer := fmt.Sprintf("%d.%d.%d", verMajor, verMinor, verMicro)
+	t.Logf("testing against libseccomp %s", curVer)
+	if curVer != expVer {
+		t.Fatalf("libseccomp version mismatch: must be %s, got %s", expVer, curVer)
+	}
+}
+
 // Type Function Tests
 
 func APILevelIsSupported() bool {