Golangci-lint: func TestXXX is unused (unused)

[hiromaily]

To detect unused func, I enable only unused linter. However, there are many detections func TestXXXX is unused (unused)
I expect any tests are used and wanna skip any TestXXX func from unused.

---

1. Version of golangci-lint: golangci-lint --version (or git commit if you don't use binary distribution)

1. Config file: cat .golangci.yml

run:
  deadline: 10m
  build-tags:
    - integration
  skip-dirs:
    - vendor

linters-settings:
  misspell:
    locale: US
  unused:
    check-exported: true

linters:
  disable-all: true
  enable:
    - unused
  presets:
    - format
    - unused
  fast: false

1. Go environment: go version && go env

$ go version                                                                                                                                                                                 go version go1.13.1 darwin/amd64

$ go env                                                                                                                                                                                 GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/myname/Library/Caches/go-build"
GOENV="/Users/myname/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/myname/work/go"
GOPRIVATE=""
GOPROXY="direct"
GOROOT="/usr/local/Cellar/go/1.13.1/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.13.1/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/myname/work/go/src/github.com/myproject/repository/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/9n/zjbb8_mx08nc4q3q9q6bck916qy5dd/T/go-build706206117=/tmp/go-build -gno-record-gcc-switches -fno-common"

[tpounds]

@hiromaily This sounds like a possible bug but I think we might need a bit more details to reproduce. Would it be possible to provide a minimal example test.go file and the golangci-lint command line you are using that triggers the incorrect behavior?

[hiromaily]

@tpounds
One of func which is detected as unused is

func TestHealthChecker_Check_Timeout(t *testing.T) {
    ctx, cancel := context.WithTimeout(context.Background(), time.Duration(1*time.Second))
    defer cancel()
    hc := NewHealthChecker(&config.Root{}, heavyCheck)
    err := hc.Check(ctx)
    assert.EqualError(t, err, context.DeadlineExceeded.Error())
}

run command line is

golangci-lint run

[hiromaily]

Not only Test func, there are many unexposed funcs and types are detected as unused.

[SimonT90poe]

We are seeing this problem with versions 1.19.0 and above. No false positives for unused test functions with 1.18.0, tested with go 1.13.

[hiromaily]

@SimonT90poe
Is it regresssion error?

[SimonT90poe]

Is it regresssion error? Anyway it should be worked on latest version is 1.21.

Every version between 1.19 and 1.21 inclusive exhibits this behaviour.
It was a surprise that TestMain() and most of the test functions it executed are considered unused. Note that --tests=false hid the problem, but obviously didn't check the test code.

[hiromaily]

Ideally, *_test.go code should be checked likewise.

[AlekSi]

It is very annoying.
@tpounds Do you still need more info? Maybe that label can be removed.

[tpounds]

@AlekSi This definitely sounds like a bug. Can someone provide a minimal test case that can be used to reproduce the issue?

[cjyar]

a.go:

package a

func a() int {
    return 0
}

a_test.go:

package a

import (
    "testing"
)

func TestA(t *testing.T) {
    if a() != 0 {
        t.Error()
    }
}

result:

a/a.go:3:6: func a is unused (unused)
func a() int {
^
a/a_test.go:7:6: func TestA is unused (unused)
func TestA(t *testing.T) {
^

[cjyar]

Workaround in .golangci.yml:

issues:
  exclude-rules:
  - path: _test\.go
    linters:
    - unused

[tsaikd]

An interesting thing: ExampleXXX will pass the lint, but TestXXX and BenchmarkXXX will fail.

Here is a reproducible demo project.

https://github.com/tsaikd/go-demo-unused/tree/v1.27.0