Add dispatch and registration benchmarks

internal/cobra/performance_test.go

@@ -0,0 +1,62 @@
+package cobra
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"testing"
+)
+
+func BenchmarkPerformanceParse(b *testing.B) {
+	wide := performanceFlatTree(128)
+	wideArgs := []string{"wide127"}
+	deep, deepArgs := performanceNestedTree(24)
+	options := ParseOptions{Context: context.Background(), Out: io.Discard, Err: io.Discard}
+
+	for _, benchmark := range []struct {
+		name string
+		root *Command
+		args []string
+	}{
+		{name: "shallow_wide", root: wide, args: wideArgs},
+		{name: "deep", root: deep, args: deepArgs},
+	} {
+		b.Run(benchmark.name, func(b *testing.B) {
+			result := Parse(benchmark.root, benchmark.args, options)
+			if result.Failure != nil {
+				b.Fatalf("fixture parse failed: %s", result.Failure.Message)
+			}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				result := Parse(benchmark.root, benchmark.args, options)
+				if result.Failure != nil {
+					b.Fatalf("parse failed: %s", result.Failure.Message)
+				}
+			}
+		})
+	}
+}
+
+func performanceFlatTree(count int) *Command {
+	root := &Command{Name: "app", Children: make([]*Command, count)}
+	for index := range root.Children {
+		root.Children[index] = &Command{Name: fmt.Sprintf("wide%03d", index), Runnable: true}
+	}
+	return root
+}
+
+func performanceNestedTree(depth int) (*Command, []string) {
+	path := make([]string, depth)
+	for index := range path {
+		path[index] = fmt.Sprintf("level%02d", index)
+	}
+	current := &Command{Name: path[depth-1], Runnable: true}
+	for index := depth - 2; index >= 0; index-- {
+		current = &Command{Name: path[index], Children: []*Command{
+			current,
+			{Name: fmt.Sprintf("sibling%02d", index), Runnable: true},
+		}}
+	}
+	return &Command{Name: "app", Children: []*Command{current}}, path
+}