ignore 'vendor' and 'testdata' directories and directories with names…

… that begin with '.' or '_'

Fixes #42

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Changed
+- Ignore `vendor` and `testdata` directories and directories with names
+  that begin with `.` or `_`
+
 ## [0.4.0] - 2021-12-19
 ### Added
 - Support method receivers with type parameters introduced in Go 1.18

analyze.go

@@ -41,6 +41,9 @@ func Analyze(paths []string, ignore *regexp.Regexp) Stats {
 
 func analyzeDir(dirname string, ignore *regexp.Regexp, stats Stats) Stats {
 	filepath.WalkDir(dirname, func(path string, entry fs.DirEntry, err error) error {
+		if isSkipDir(entry) {
+			return filepath.SkipDir
+		}
 		if err == nil && isGoFile(entry) {
 			stats = analyzeFile(path, ignore, stats)
 		}
@@ -49,6 +52,17 @@ func analyzeDir(dirname string, ignore *regexp.Regexp, stats Stats) Stats {
 	return stats
 }
 
+var skipDirs = map[string]bool{
+	"testdata": true,
+	"vendor":   true,
+}
+
+func isSkipDir(entry fs.DirEntry) bool {
+	return entry.IsDir() && (skipDirs[entry.Name()] ||
+		strings.HasPrefix(entry.Name(), ".") ||
+		strings.HasPrefix(entry.Name(), "_"))
+}
+
 func isGoFile(entry fs.DirEntry) bool {
 	return !entry.IsDir() && strings.HasSuffix(entry.Name(), ".go")
 }

analyze_test.go

@@ -75,6 +75,10 @@ func TestAnalyze(t *testing.T) {
 			`1 directory b testdata/directory/file2.go:3:1
 1 directory a testdata/directory/file1.go:3:1`,
 		},
+		{
+			[]string{"testdata/ignore"},
+			"",
+		},
 	}
 
 	for _, tt := range tests {

testdata/ignore/.dotname/file.go

@@ -0,0 +1,3 @@
+package dotname
+
+func a() {}

testdata/ignore/_underscore/file.go

@@ -0,0 +1,3 @@
+package underscore
+
+func a() {}

testdata/ignore/testdata/file.go

@@ -0,0 +1,3 @@
+package testdata
+
+func a() {}

testdata/ignore/vendor/file.go

@@ -0,0 +1,3 @@
+package vendor
+
+func a() {}