Finally I can add this: traversal benchmarks.

Lots of import cycle fixing was necessary to get here, which was an
unpleasant surprise at the start of the day... but lots of things are
better off now, so it was highly worth it.

impl/free/bench_test.go

@@ -94,6 +94,12 @@ func BenchmarkMarshalMapStrInt_3n(b *testing.B) {
 	tests.SpecBenchmarkMarshalMapStrInt_3n(b, NodeBuilder())
 }
 
+// benchmarks covering traversal -->
+
+func BenchmarkWalkMapStrInt_3n(b *testing.B) {
+	tests.SpecBenchmarkWalkMapStrInt_3n(b, NodeBuilder())
+}
+
 // copy of helper functions from must package, because import cycles, sigh -->
 
 func mustNotError(e error) {

tests/traversalBenchmarks.go

+package tests
+
+import (
+	"bytes"
+	"testing"
+
+	refmtjson "github.com/polydawn/refmt/json"
+
+	ipld "github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/encoding"
+	"github.com/ipld/go-ipld-prime/tests/corpus"
+	"github.com/ipld/go-ipld-prime/traversal"
+	"github.com/ipld/go-ipld-prime/traversal/selector"
+)
+
+func SpecBenchmarkWalkMapStrInt_3n(b *testing.B, nb ipld.NodeBuilder) {
+	n, err := encoding.Unmarshal(nb, refmtjson.NewDecoder(bytes.NewBufferString(corpus.Map3StrInt())))
+	if err != nil {
+		panic(err)
+	}
+	seldefn, err := encoding.Unmarshal(nb, refmtjson.NewDecoder(bytes.NewBufferString(`{"a":{">":{".":{}}}}`)))
+	if err != nil {
+		panic(err)
+	}
+	sel, err := selector.ParseSelector(seldefn)
+	if err != nil {
+		panic(err)
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		traversal.WalkMatching(n, sel, func(tp traversal.Progress, n ipld.Node) error {
+			return nil // no need to do anything here; just care about exercising the walk internals.
+		})
+	}
+}