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gometalinter で楽々 lint

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Go 言語用の lint ツールはいくつかあるのだが,これらを統合的に扱える gometalinter というのがあるらしい。

Go 言語で書かれているので(Go 言語の環境があれば)インストールは簡単。

$ go get -v github.com/alecthomas/gometalinter

gometalinter をつかって各種 lint およびフォーマッタ・ツールを一気にインストールできる。

$ gometalinter --install --update

Installing:
structcheck
interfacer
goconst
golint
goimports
dupl
errcheck
aligncheck
gocyclo
ineffassign
unconvert
gotype
varcheck
deadcode
lll

これらのツールは $GOPATH/bin フォルダにインストールされるので PATH を通しておくこと。

では早速試してみよう。サンプルコードは,このまえ手遊びで作った github.com/spiegel-im-spiegel/zundoko パッケージを使おう。

$ go get -v github.com/spiegel-im-spiegel/zundoko

いきなり lint をかけてみる。

$ gometalinter ./...

WARNING: deadline exceeded by linter dupl on sample (try increasing --deadline)
WARNING: deadline exceeded by linter unconvert on . (try increasing --deadline)
WARNING: deadline exceeded by linter unconvert on sample (try increasing --deadline)
WARNING: deadline exceeded by linter aligncheck on . (try increasing --deadline)
WARNING: deadline exceeded by linter aligncheck on sample (try increasing --deadline)
WARNING: deadline exceeded by linter interfacer on . (try increasing --deadline)
WARNING: deadline exceeded by linter interfacer on sample (try increasing --deadline)

ありゃりゃ。処理に時間がかかりすぎた? じゃあ --fast オプション1 を付けてもう一度。

$ gometalinter --fast ./...

WARNING: deadline exceeded by linter dupl on sample (try increasing --deadline)

う~ん。実は私の環境では gometalinterdupl の終了を認識してくれないようだ2。なので dupl を除外してやってみる。

$ gometalinter --fast --disable=dupl ./...

今度はエラーは出なかった。なお --deadline=5s といった感じで deadline 値を調整すれば --fast オプションなしでも上手くいく。

では github.com/spiegel-im-spiegel/zundoko パッケージの zundoko.go ファイルを以下のように弄ってみる。

package zundoko

import (
"math/rand"
"time"
)

// zundoko-choirs items
const (
Zun = "ズン"
Doko = "ドコ"
Kiyoshi = "キ・ヨ・シ!"
)

//Choirs - zundoko-choirs list
type Choirs struct {
c []string
dummy int
}

//Push is append choirs
func (c *Choirs) Push(s string) {
c.c = append(c.c, s) //maybe panic if c is nil.
}

//CountZunDoko returns count of "ZUN" and "DOKO" choirs
func (c *Choirs) CountZunDoko() (int, int) {
z := 0
d := 0
if c == nil {
return z, d
}
for _, s := range c.c {
switch s {
case Zun:
z++
case Doko:
d++
}
}
return z, d
}

func (c *Choirs) String() string {
if c == nil {
return ""
} else {
content := make([]byte, 0, 128)
for _, s := range c.c {
content = append(content, s...)
}
return string(content)
}
return ""
}

func generate() chan string {
ch := make(chan string)
go func() {
zd := [2]string{Zun, Doko}
rand.Seed(time.Now().UnixNano())
for {
ch <- zd[rand.Intn(2)]
}
}()
return ch
}

//Run zundoko-choirs
func Run() *Choirs {
zd := generate()
c := &Choirs{c: make([]string, 0)}
zcount := 0
for {
s := <-zd
c.Push(s)
if s == Zun {
zcount++
} else if zcount >= 4 {
break
} else {
zcount = 0
}
}
c.Push(Kiyoshi)
return c
}

どこに問題があるかお分かりだろうか。 lint をかけると以下の結果になる。

$ gometalinter --deadline=5s --disable=dupl ./...

zundoko.go:72:32:error: too few values in struct literal (gotype)
zundoko.go:54::error: unreachable code (vet)
zundoko.go:47:9:warning: if block ends with a return statement, so drop this else and outdent its block (golint)
zundoko.go:72:32:warning: too few values in struct literal (interfacer)

golint, gotype, interfacer, vet のそれぞれのエラー・ワーニングが集約されて出力されているのがわかると思う。ちなみに --json オプションを付けると出力が JSON フォーマットになる。

$ gometalinter --deadline=5s --disable=dupl --json ./...

[
{"linter":"golint","severity":"warning","path":"zundoko.go","line":47,"col":9,"message":"if block ends with a return statement, so drop this else and outdent its block"},
{"linter":"gotype","severity":"error","path":"zundoko.go","line":72,"col":32,"message":"too few values in struct literal"},
{"linter":"vet","severity":"error","path":"zundoko.go","line":54,"col":0,"message":"unreachable code"},
{"linter":"interfacer","severity":"warning","path":"zundoko.go","line":72,"col":32,"message":"too few values in struct literal"}
]

また --vendor オプションを付けると Go 言語バージョン 1.5 から採用された Vendoring 機能に対応する。その他,オプション等は以下のとおり。

$ gometalinter --help

usage: gometalinter.exe [<flags>] [<path>...]

Aggregate and normalise the output of a whole bunch of Go linters.

Default linters:

deadcode (github.com/tsenart/deadcode)
deadcode .
^deadcode: (?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$
gocyclo (github.com/alecthomas/gocyclo)
gocyclo -over {mincyclo} .
^(?P<cyclo>\d+)\s+\S+\s(?P<function>\S+)\s+(?P<path>[^:]+):(?P<line>\d+):(\d+)$
gofmt
gofmt -l -s ./*.go
^(?P<path>[^\n]+)$
gotype (golang.org/x/tools/cmd/gotype)
gotype -e {tests=-a} .
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$
ineffassign (github.com/gordonklaus/ineffassign)
ineffassign -n .
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$
vetshadow
go tool vet --shadow ./*.go
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):\s*(?P<message>.*)$
varcheck (github.com/opennota/check/cmd/varcheck)
varcheck .
^(?:[^:]+: )?(?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>\w+)$
vet
go tool vet ./*.go
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):\s*(?P<message>.*)$
aligncheck (github.com/opennota/check/cmd/aligncheck)
aligncheck .
^(?:[^:]+: )?(?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.+)$
dupl (github.com/mibk/dupl)
dupl -plumbing -threshold {duplthreshold} ./*.go
^(?P<path>[^\s][^:]+?\.go):(?P<line>\d+)-\d+:\s*(?P<message>.*)$
golint (github.com/golang/lint/golint)
golint -min_confidence {min_confidence} .
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$
lll (github.com/walle/lll/cmd/lll)
lll -g -l {maxlinelength} ./*.go
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):\s*(?P<message>.*)$
structcheck (github.com/opennota/check/cmd/structcheck)
structcheck {tests=-t} .
^(?:[^:]+: )?(?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.+)$
testify
go test
Location:\s+(?P<path>[^:]+):(?P<line>\d+)$\s+Error:\s+(?P<message>[^\n]+)
errcheck (github.com/kisielk/errcheck)
errcheck -abspath .
^(?P<path>[^:]+):(?P<line>\d+):(?P<col>\d+)\t(?P<message>.*)$
goconst (github.com/jgautheron/goconst/cmd/goconst)
goconst -min-occurrences {min_occurrences} .
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$
goimports (golang.org/x/tools/cmd/goimports)
goimports -l ./*.go
^(?P<path>[^\n]+)$
interfacer (github.com/mvdan/interfacer/cmd/interfacer)
interfacer ./
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$
test
go test
^--- FAIL: .*$\s+(?P<path>[^:]+):(?P<line>\d+): (?P<message>.*)$
unconvert (github.com/mdempsky/unconvert)
unconvert .
^(?P<path>[^\s][^\r\n:]+?\.go):(?P<line>\d+):(?P<col>\d+):\s*(?P<message>.*)$

Severity override map (default is "warning"):

gotype -> error
test -> error
testify -> error
vet -> error

Flags:
--help Show context-sensitive help (also try --help-long
and --help-man).
--fast Only run fast linters.
-i, --install Attempt to install all known linters.
-u, --update Pass -u to go tool when installing.
-f, --force Pass -f to go tool when installing.
-d, --debug Display messages for failed linters, etc.
-j, --concurrency=16 Number of concurrent linters to run.
-e, --exclude=REGEXP ... Exclude messages matching these regular expressions.
-I, --include=REGEXP ... Include messages matching these regular expressions.
-s, --skip=DIR... ... Skip directories with this name when expanding
'...'.
--vendor Enable vendoring support (skips 'vendor' directories
and sets GO15VENDOREXPERIMENT=1).
--cyclo-over=10 Report functions with cyclomatic complexity over N
(using gocyclo).
--line-length=80 Report lines longer than N (using lll).
--min-confidence=.80 Minimum confidence interval to pass to golint.
--min-occurrences=3 Minimum occurrences to pass to goconst.
--dupl-threshold=50 Minimum token sequence as a clone for dupl.
--sort=none ... Sort output by any of none, path, line, column,
severity, message, linter.
-t, --tests Include test files for linters that support this
option
--deadline=5s Cancel linters if they have not completed within
this duration.
--errors Only show errors.
--json Generate structured JSON rather than standard
line-based output.
-D, --disable=LINTER ... List of linters to disable
(testify,test,gofmt,goimports,lll).
-E, --enable=LINTER ... Enable previously disabled linters.
--linter=NAME:COMMAND:PATTERN ...
Specify a linter.
--message-overrides=LINTER:MESSAGE ...
Override message from linter. {message} will be
expanded to the original message.
--severity=LINTER:SEVERITY ...
Map of linter severities.
--disable-all Disable all linters.

Args:
[<path>] Directory to lint. Defaults to ".". <path>/... will recurse.

Vim, emacs, ATOM などでは gometalinter を使ったプラグインやパッケージが公開されているようだ。


脚注





  1. --fast オプションを付けると deadcode, dupl, goconst, gocyclo, golint, gotype, vet といった処理の速いツールのみでチェックを行う。 



  2. 手動で dupl -plumbing -threshold 50 zundoko.go とかやってみたが問題なく動作しているので gometalinter 側の問題だろう,多分。