Benchmark tool command line issues: "go test -bench ." works but "go test -bench=." doesn't #73593

RickSanch3z · 2025-05-03T14:53:44Z

Go version

go version go1.24.2 windows/amd64

Output of `go env` in your module/workspace:

set AR=ar
set CC=gcc
set CGO_CFLAGS=-O2 -g
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-O2 -g
set CGO_ENABLED=0
set CGO_FFLAGS=-O2 -g
set CGO_LDFLAGS=-O2 -g
set CXX=g++
set GCCGO=gccgo
set GO111MODULE=
set GOAMD64=v1
set GOARCH=amd64
set GOAUTH=netrc
set GOBIN=
set GOCACHE=C:\Users\u1\AppData\Local\go-build
set GOCACHEPROG=
set GODEBUG=
set GOENV=C:\Users\u1\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFIPS140=off
set GOFLAGS=
set GOGCCFLAGS=-m64 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=C:\Users\USER_N~1\AppData\Local\Temp\go-build3576284606=/tmp/go-build -gno-record-gcc-switches
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMOD=E:\go\ch1\echo_test\go.mod
set GOMODCACHE=C:\Users\u1\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\u1\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:\Program Files\Go
set GOSUMDB=sum.golang.org
set GOTELEMETRY=local
set GOTELEMETRYDIR=C:\Users\u1\AppData\Roaming\go\telemetry
set GOTMPDIR=
set GOTOOLCHAIN=auto
set GOTOOLDIR=C:\Program Files\Go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.24.2
set GOWORK=
set PKG_CONFIG=pkg-config

What did you do?

Tried to run "go test" benchmark tool.
Here's the code:

package echo_test

import (
	"strings"
	"testing"
)

var (
	args_slice = []string{"a0", "a1", "a2", "a3", "a4"}
	sep string = ""
	s string = ""
)

func BenchmarkEchoStandardLoop(b *testing.B) {
	s = ""
	sep = ""
	for i := 0; i < b.N; i++ {
		for j := 0; j < len(args_slice); j++ {
			s += sep + args_slice[j]
			sep = " "
		}
	}
}

func BenchmarkEchoRangeLoop(b *testing.B) {
	s = ""
	sep = ""
	for i := 0; i < b.N; i++ {
		for _, arg := range args_slice {
			s += sep + arg
			sep = " "
		}
	}
}

func BenchmarkEchoStringsJoin(b *testing.B) {
	s = ""
	sep = ""
	for i := 0; i < b.N; i++ {
		s = strings.Join(args_slice, " ")
	}
}

What did you see happen?

With "go test -bench=." it printed:

ok echo_test 0.291s [no tests to run]

But with "go test -bench ." it launched the benchmark:

...
BenchmarkEchoStandardLoop-8 16408 109289 ns/op
BenchmarkEchoRangeLoop-8 17733 127269 ns/op
BenchmarkEchoStringsJoin-8 13529373 85.89 ns/op

What did you expect to see?

Expected to see the result of the benchmark.

The text was updated successfully, but these errors were encountered:

gabyhelp · 2025-05-03T15:13:41Z

Related Issues

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

seankhliao · 2025-05-03T15:17:10Z

This is a powershell bug where it passes -bench=. to programs as 2 args: -bench= and ..
PowerShell/PowerShell#6291

RickSanch3z changed the title ~~Benchmark tool command line issues: "go test -bench ." works but "go test -bench=."~~ Benchmark tool command line issues: "go test -bench ." works but "go test -bench=." doesn't May 3, 2025

gabyhelp added the ToolProposal Issues describing a requested change to a Go tool or command-line program. label May 3, 2025

seankhliao closed this as completed May 3, 2025

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Benchmark tool command line issues: "go test -bench ." works but "go test -bench=." doesn't #73593

Benchmark tool command line issues: "go test -bench ." works but "go test -bench=." doesn't #73593

Benchmark tool command line issues: "go test -bench ." works but "go test -bench=." doesn't #73593

Benchmark tool command line issues: "go test -bench ." works but "go test -bench=." doesn't #73593

Comments

Go version

Output of go env in your module/workspace:

What did you do?

What did you see happen?

What did you expect to see?

Output of `go env` in your module/workspace: