Refactor repoFinder

- Remove io package and move finder to git package
- Move tempDir and writeFile into test package. They are only used for testing purposes anyway.
- Add a way to specify parent folder for tempDir. Useful for testing nested repos.
- Add new test repos with .git/config files

pkg/git/finder.go

@@ -0,0 +1,102 @@
+package git
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/karrick/godirwalk"
+	"github.com/pkg/errors"
+)
+
+// errSkipNode is used as an error indicating that .git directory has been found.
+// It's handled by ErrorsCallback to tell the WalkCallback to skip this dir.
+var errSkipNode = errors.New(".git directory found, skipping this node")
+
+// errDirectoryAccess indicates a directory doesn't exists or can't be accessed
+var errDirectoryAccess = errors.New("directory doesn't exist or can't be accessed")
+
+// Exists returns true if a directory exists. If it doesn't or the directory can't be accessed it returns an error.
+func Exists(path string) (bool, error) {
+	_, err := os.Stat(path)
+
+	if err == nil {
+		return true, nil
+	}
+
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, errDirectoryAccess
+		}
+	}
+
+	// Directory exists but can't be accessed
+	return true, errDirectoryAccess
+}
+
+// RepoFinder finds paths to git repos inside given path.
+type RepoFinder struct {
+	root  string
+	repos []string
+}
+
+// NewRepoFinder returns a RepoFinder pointed at given root path.
+func NewRepoFinder(root string) *RepoFinder {
+	return &RepoFinder{
+		root: root,
+	}
+}
+
+// Find returns a sorted list of paths to git repos found inside a given root path.
+// Returns error if root repo path can't be found or accessed.
+func (r *RepoFinder) Find() ([]string, error) {
+	if _, err := Exists(r.root); err != nil {
+		return nil, err
+	}
+
+	walkOpts := &godirwalk.Options{
+		ErrorCallback: r.errorCb,
+		Callback:      r.walkCb,
+		// Use Unsorted to improve speed because repos will be processed by goroutines in a random order anyway.
+		Unsorted: true,
+	}
+
+	err := godirwalk.Walk(r.root, walkOpts)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(r.repos) == 0 {
+		return nil, fmt.Errorf("no git repos found in root path %s", r.root)
+	}
+
+	return r.repos, nil
+}
+
+func (r *RepoFinder) walkCb(path string, ent *godirwalk.Dirent) error {
+	// Do not traverse .git directories
+	if ent.IsDir() && ent.Name() == ".git" {
+		r.repos = append(r.repos, strings.TrimSuffix(path, ".git"))
+		return errSkipNode
+	}
+	// Do not traverse directories containing a .git directory
+	if ent.IsDir() {
+		_, err := os.Stat(filepath.Join(path, ".git"))
+		if err == nil {
+			r.repos = append(r.repos, strings.TrimSuffix(path, ".git"))
+			return ErrSkipNode
+		}
+	}
+	return nil
+}
+
+func (r *RepoFinder) errorCb(_ string, err error) godirwalk.ErrorAction {
+	// Skip .git directory and directories we don't have permissions to access
+	// TODO: Will syscall.EACCES work on windows?
+	if errors.Is(err, errSkipNode) || errors.Is(err, syscall.EACCES) {
+		return godirwalk.SkipNode
+	}
+	return godirwalk.Halt
+}