engine: graph: autogroup: Ensure we sort correctly

This should ensure this sort order of longer thing first, when running
the algorithm. We want to autogroup two or more http:server:flag
resources together first, before the whole grouped resource gets pulled
into the http:server one.

engine/graph/autogroup/util_test.go

@@ -0,0 +1,84 @@
+// Mgmt
+// Copyright (C) James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+// Additional permission under GNU GPL version 3 section 7
+//
+// If you modify this program, or any covered work, by linking or combining it
+// with embedded mcl code and modules (and that the embedded mcl code and
+// modules which link with this program, contain a copy of their source code in
+// the authoritative form) containing parts covered by the terms of any other
+// license, the licensors of this program grant you additional permission to
+// convey the resulting work. Furthermore, the licensors of this program grant
+// the original author, James Shubin, additional permission to update this
+// additional permission if he deems it necessary to achieve the goals of this
+// additional permission.
+
+//go:build !root
+
+package autogroup
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/purpleidea/mgmt/engine"
+	_ "github.com/purpleidea/mgmt/engine/resources" // import so the resources register
+	"github.com/purpleidea/mgmt/pgraph"
+)
+
+// ListPgraphVertexCmp compares two lists of pgraph.Vertex pointers.
+func ListPgraphVertexCmp(a, b []pgraph.Vertex) bool {
+	//fmt.Printf("CMP: %v with %v\n", a, b) // debugging
+	if a == nil && b == nil {
+		return true
+	}
+	if a == nil || b == nil {
+		return false
+	}
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// empty graph
+func TestRHVSort1(t *testing.T) {
+
+	r1, err := engine.NewNamedResource("http:server", "foo")
+	if err != nil {
+		panic(fmt.Sprintf("unexpected error: %+v", err))
+	}
+	r2, err := engine.NewNamedResource("http:server:ui", "bar")
+	if err != nil {
+		panic(fmt.Sprintf("unexpected error: %+v", err))
+	}
+
+	vertices := []pgraph.Vertex{r1, r2}
+	expected := []pgraph.Vertex{r2, r1}
+
+	if out := RHVSort(vertices); !ListPgraphVertexCmp(expected, out) {
+		t.Errorf("vertices: %+v", vertices)
+		t.Errorf("expected: %+v", expected)
+		t.Errorf("test out: %+v", out)
+	}
+
+}