[autodetect] Add go autodetection (jetify-com#2381)

## Summary TSIA. ## How was it tested? unit tests

Author: mikeland73

pkg/autodetect/autodetect.go

@@ -43,6 +43,7 @@ func detectors(path string) []detector.Detector {
 return []detector.Detector{
 &detector.PythonDetector{Root: path},
 &detector.PoetryDetector{Root: path},
+&detector.GoDetector{Root: path},
 }
 }
 

pkg/autodetect/detector/go.go

@@ -0,0 +1,53 @@
+package detector
+
+import (
+"context"
+"os"
+"path/filepath"
+"regexp"
+)
+
+type GoDetector struct {
+Root string
+}
+
+var _ Detector = &GoDetector{}
+
+func (d *GoDetector) Relevance(path string) (float64, error) {
+goModPath := filepath.Join(d.Root, "go.mod")
+_, err := os.Stat(goModPath)
+if err == nil {
+return 1.0, nil
+}
+if os.IsNotExist(err) {
+return 0, nil
+}
+return 0, err
+}
+
+func (d *GoDetector) Packages(ctx context.Context) ([]string, error) {
+goModPath := filepath.Join(d.Root, "go.mod")
+goModContent, err := os.ReadFile(goModPath)
+if err != nil {
+return nil, err
+}
+
+// Parse the Go version from go.mod
+goVersion := parseGoVersion(string(goModContent))
+if goVersion != "" {
+return []string{"go@" + goVersion}, nil
+}
+return []string{"go@latest"}, nil
+}
+
+func parseGoVersion(goModContent string) string {
+// Use a regular expression to find the Go version directive
+re := regexp.MustCompile(`(?m)^go\s+(\d+\.\d+(\.\d+)?)`)
+match := re.FindStringSubmatch(goModContent)
+
+if len(match) >= 2 {
+return match[1]
+}
+
+return ""
+}

pkg/autodetect/detector/go_test.go

@@ -0,0 +1,103 @@
+package detector
+
+import (
+"context"
+"os"
+"path/filepath"
+"testing"
+
+"github.com/stretchr/testify/assert"
+)
+
+func TestGoDetectorRelevance(t *testing.T) {
+tempDir := t.TempDir()
+detector := &GoDetector{Root: tempDir}
+
+t.Run("No go.mod file", func(t *testing.T) {
+relevance, err := detector.Relevance(tempDir)
+assert.NoError(t, err)
+assert.Equal(t, 0.0, relevance)
+})
+
+t.Run("With go.mod file", func(t *testing.T) {
+err := os.WriteFile(filepath.Join(tempDir, "go.mod"), []byte("module example.com"), 0o644)
+assert.NoError(t, err)
+
+relevance, err := detector.Relevance(tempDir)
+assert.NoError(t, err)
+assert.Equal(t, 1.0, relevance)
+})
+}
+
+func TestGoDetectorPackages(t *testing.T) {
+tempDir := t.TempDir()
+detector := &GoDetector{Root: tempDir}
+
+t.Run("No go.mod file", func(t *testing.T) {
+packages, err := detector.Packages(context.Background())
+assert.Error(t, err)
+assert.Nil(t, packages)
+})
+
+t.Run("With go.mod file and no version", func(t *testing.T) {
+err := os.WriteFile(filepath.Join(tempDir, "go.mod"), []byte("module example.com"), 0o644)
+assert.NoError(t, err)
+
+packages, err := detector.Packages(context.Background())
+assert.NoError(t, err)
+assert.Equal(t, []string{"go@latest"}, packages)
+})
+
+t.Run("With go.mod file and specific version", func(t *testing.T) {
+goModContent := `
+module example.com
+
+go 1.18
+`
+err := os.WriteFile(filepath.Join(tempDir, "go.mod"), []byte(goModContent), 0o644)
+assert.NoError(t, err)
+
+packages, err := detector.Packages(context.Background())
+assert.NoError(t, err)
+assert.Equal(t, []string{"go@1.18"}, packages)
+})
+}
+
+func TestParseGoVersion(t *testing.T) {
+testCases := []struct {
+name string
+content string
+expected string
+}{
+{
+name: "No version",
+content: "module example.com",
+expected: "",
+},
+{
+name: "With version",
+content: `
+module example.com
+
+go 1.18
+`,
+expected: "1.18",
+},
+{
+name: "With patch version",
+content: `
+module example.com
+
+go 1.18.3
+`,
+expected: "1.18.3",
+},
+}
+
+for _, tc := range testCases {
+t.Run(tc.name, func(t *testing.T) {
+version := parseGoVersion(tc.content)
+assert.Equal(t, tc.expected, version)
+})
+}
+}