update comments

internal/command/graph_test.go

@@ -59,14 +59,15 @@ func TestGraph_cyclic(t *testing.T) {
 		name     string
 		args     []string
 		expected string
-		errors   []string
+
+		// The cyclic errors do not maintain a consistent order, so we can't
+		// predict the exact output. We'll just check that the error messages
+		// are present for the things we know are cyclic.
+		errors []string
 	}{
 		{
 			name: "plan",
 			args: []string{"-type=plan"},
-			// The cyclic errors do not maintain a consistent order, so we can't
-			// predict the exact output. We'll just check that the error messages
-			// are present for the things we know are cyclic.
 			errors: []string{`Error: Cycle: test_instance.`,
 				`Error: Cycle: local.`},
 		},

internal/dag/dot.go

@@ -211,6 +211,7 @@ func (g *marshalGraph) writeBody(opts *DotOpts, w *indentWriter) {
 
 	for _, e := range g.Edges {
 		// only add the edge if it's not been added as part of a cycle
+		// or if there are duplicates.
 		if _, ok := dotEdges[e.Name]; !ok {
 			dotEdges[e.Name] = e.dot(g)
 		}