Initial commit

.gitignore

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+gochecknoglobals

.travis.yml

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+language: go
+
+go:
+  - "1.x"
+
+go_import_path: 4d63.com/gochecknoglobals
+
+script:
+  - go test -coverprofile=coverage.txt
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)

LICENSE

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+MIT License
+
+Copyright (c) 2018 Leigh McCulloch
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# gochecknoglobals
+
+[![Build Status](https://img.shields.io/travis/leighmcculloch/gochecknoglobals.svg)](https://travis-ci.org/leighmcculloch/gochecknoglobals)
+[![Codecov](https://img.shields.io/codecov/c/github/leighmcculloch/gochecknoglobals.svg)](https://codecov.io/gh/leighmcculloch/gochecknoglobals)
+[![Go Report Card](https://goreportcard.com/badge/github.com/leighmcculloch/gochecknoglobals)](https://goreportcard.com/report/github.com/leighmcculloch/gochecknoglobals)
+
+Check that no globals are present in Go code.
+
+## Why
+
+Global variables are an input to functions that is not visible in the functions signature, complicate testing, reduces readability and increase the complexity of code.
+
+https://peter.bourgon.org/blog/2017/06/09/theory-of-modern-go.html
+https://twitter.com/davecheney/status/871939730761547776
+
+## Install
+
+```
+go get 4d63.com/gochecknoglobals
+```
+
+## Usage
+
+```
+gochecknoglobals
+```
+
+or
+
+```
+gochecknoglobals [path] [path] ...
+```

check_no_globals.go

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+package main
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+	"path/filepath"
+)
+
+func checkNoGlobals(path string) ([]string, error) {
+	messages := []string{}
+
+	err := filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !info.IsDir() {
+			return nil
+		}
+
+		fset := token.NewFileSet()
+		pkgs, err := parser.ParseDir(fset, path, nil, 0)
+		if err != nil {
+			return err
+		}
+
+		for _, pkg := range pkgs {
+			for _, file := range pkg.Files {
+				for _, decl := range file.Decls {
+					genDecl, ok := decl.(*ast.GenDecl)
+					if !ok {
+						continue
+					}
+					if genDecl.Tok != token.VAR {
+						continue
+					}
+					filename := fset.Position(genDecl.TokPos).Filename
+					line := fset.Position(genDecl.TokPos).Line
+					valueSpec := genDecl.Specs[0].(*ast.ValueSpec)
+					for i := 0; i < len(valueSpec.Names); i++ {
+						name := valueSpec.Names[i].Name
+						message := fmt.Sprintf("%s:%d %s is a global variable", filename, line, name)
+						messages = append(messages, message)
+					}
+				}
+			}
+		}
+		return nil
+	})
+
+	return messages, err
+}

check_no_globals_test.go

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+package main
+
+import (
+	"path/filepath"
+	"strconv"
+	"testing"
+)
+
+func TestCheckNoGlobals(t *testing.T) {
+	cases := [][]string{
+		nil,
+		nil,
+		{
+			"testdata/2/code.go:3 myVar is a global variable",
+		},
+		{
+			"testdata/3/code_0.go:8 theVar is a global variable",
+			"testdata/3/code_1.go:3 myVar is a global variable",
+		},
+		{
+			"testdata/4/subpkg/code_1.go:3 myVar is a global variable",
+		},
+		{
+			"testdata/5/code.go:3 myVar1 is a global variable",
+			"testdata/5/code.go:3 myVar2 is a global variable",
+		},
+	}
+
+	for i, wantMessages := range cases {
+		testdataName := strconv.FormatInt(int64(i), 10)
+		t.Run(testdataName, func(t *testing.T) {
+			path := filepath.Join("testdata", testdataName)
+			messages, err := checkNoGlobals(path)
+			if err != nil {
+				t.Fatalf("got error %#v", err)
+			}
+			if !stringSlicesEqual(messages, wantMessages) {
+				t.Errorf("got %#v, want %#v", messages, wantMessages)
+			}
+		})
+	}
+}
+
+func stringSlicesEqual(s1, s2 []string) bool {
+	diff := map[string]int{}
+	for _, s := range s1 {
+		diff[s]++
+	}
+	for _, s := range s2 {
+		diff[s]--
+		if diff[s] == 0 {
+			delete(diff, s)
+		}
+	}
+	return len(diff) == 0
+}

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+)
+
+func main() {
+	flagPrintHelp := flag.Bool("help", false, "")
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Usage: gochecknoglobals [path] [path] ...\n")
+	}
+	flag.Parse()
+
+	if *flagPrintHelp {
+		flag.Usage()
+		return
+	}
+
+	paths := flag.Args()
+	if len(paths) == 0 {
+		paths = []string{"."}
+	}
+
+	for _, path := range paths {
+		messages, err := checkNoGlobals(path)
+		for _, message := range messages {
+			fmt.Fprintf(os.Stdout, "%s\n", message)
+		}
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error: %s\n", err)
+		}
+	}
+}

testdata/0/code.go

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+package code

testdata/1/code.go

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+package code
+
+const constant = 0

testdata/2/code.go

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+package code
+
+var myVar = 0

testdata/3/code_0.go

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+package code
+
+func someCode() bool {
+	yourVar := true
+	return yourVar
+}
+
+var theVar = true

testdata/3/code_1.go

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+package code
+
+var myVar = "global"

testdata/4/subpkg/code_0.go

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+package code
+
+func someCode() bool {
+	return true
+}

testdata/4/subpkg/code_1.go

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+package code
+
+var myVar = "global"

testdata/5/code.go

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+package code
+
+var myVar1, myVar2 = 1, 2