Introduce Helmfile's own filesystem abstraction to correctly unit test some components (#307)

Use abstracted FS

Signed-off-by: Arkaitz Jimenez <arkaitzj@gmail.com>

Signed-off-by: Arkaitz Jimenez <arkaitzj@gmail.com>

pkg/filesystem/fs.go

@@ -0,0 +1,101 @@
+package filesystem
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+)
+
+type FileSystem struct {
+	ReadFile          func(string) ([]byte, error)
+	ReadDir           func(string) ([]fs.DirEntry, error)
+	DeleteFile        func(string) error
+	FileExists        func(string) (bool, error)
+	Glob              func(string) ([]string, error)
+	FileExistsAt      func(string) bool
+	DirectoryExistsAt func(string) bool
+	Stat              func(string) (os.FileInfo, error)
+	Getwd             func() (string, error)
+	Chdir             func(string) error
+	Abs               func(string) (string, error)
+}
+
+func DefaultFileSystem() *FileSystem {
+	dfs := FileSystem{
+		ReadFile:   os.ReadFile,
+		ReadDir:    os.ReadDir,
+		DeleteFile: os.Remove,
+		Stat:       os.Stat,
+		Glob:       filepath.Glob,
+		Getwd:      os.Getwd,
+		Chdir:      os.Chdir,
+		Abs:        filepath.Abs,
+	}
+
+	dfs.FileExistsAt = dfs.fileExistsAtDefault
+	dfs.DirectoryExistsAt = dfs.directoryExistsDefault
+	dfs.FileExists = dfs.fileExistsDefault
+	return &dfs
+}
+
+func FromFileSystem(params FileSystem) *FileSystem {
+	dfs := DefaultFileSystem()
+
+	if params.ReadFile != nil {
+		dfs.ReadFile = params.ReadFile
+	}
+	if params.ReadDir != nil {
+		dfs.ReadDir = params.ReadDir
+	}
+	if params.DeleteFile != nil {
+		dfs.DeleteFile = params.DeleteFile
+	}
+	if params.FileExists != nil {
+		dfs.FileExists = params.FileExists
+	}
+	if params.Glob != nil {
+		dfs.Glob = params.Glob
+	}
+	if params.FileExistsAt != nil {
+		dfs.FileExistsAt = params.FileExistsAt
+	}
+	if params.DirectoryExistsAt != nil {
+		dfs.DirectoryExistsAt = params.DirectoryExistsAt
+	}
+	if params.Stat != nil {
+		dfs.Stat = params.Stat
+	}
+	if params.Getwd != nil {
+		dfs.Getwd = params.Getwd
+	}
+	if params.Chdir != nil {
+		dfs.Chdir = params.Chdir
+	}
+	if params.Abs != nil {
+		dfs.Abs = params.Abs
+	}
+
+	return dfs
+}
+
+func (filesystem *FileSystem) fileExistsAtDefault(path string) bool {
+	fileInfo, err := filesystem.Stat(path)
+	return err == nil && fileInfo.Mode().IsRegular()
+}
+
+func (filesystem *FileSystem) fileExistsDefault(path string) (bool, error) {
+	_, err := filesystem.Stat(path)
+
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	return true, nil
+}
+
+func (filesystem *FileSystem) directoryExistsDefault(path string) bool {
+	fileInfo, err := filesystem.Stat(path)
+	return err == nil && fileInfo.Mode().IsDir()
+}

pkg/filesystem/fs_test.go

@@ -0,0 +1,98 @@
+package filesystem
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"strings"
+	"testing"
+	"time"
+)
+
+type TestFileInfo struct {
+	mode fs.FileMode
+}
+
+func (tfi TestFileInfo) Name() string       { return "" }
+func (tfi TestFileInfo) Size() int64        { return 0 }
+func (tfi TestFileInfo) Mode() fs.FileMode  { return tfi.mode }
+func (tfi TestFileInfo) ModTime() time.Time { return time.Time{} }
+func (tfi TestFileInfo) IsDir() bool        { return tfi.mode.IsDir() }
+func (tfi TestFileInfo) Sys() any           { return nil }
+
+func NewTestFileSystem() FileSystem {
+	replaceffs := FileSystem{
+		Stat: func(s string) (os.FileInfo, error) {
+			if strings.HasPrefix(s, "existing_file") {
+				return TestFileInfo{mode: 0}, nil
+			}
+			if strings.HasPrefix(s, "existing_dir") {
+				return TestFileInfo{mode: fs.ModeDir}, nil
+			}
+			return nil, errors.New("Error")
+		},
+	}
+	return *FromFileSystem(replaceffs)
+}
+
+func TestFs_fileExistsDefault(t *testing.T) {
+	ffs := NewTestFileSystem()
+	var exists, _ = ffs.FileExists("existing_file.txt")
+	if !exists {
+		t.Errorf("Expected file %s, not found", "existing_file.txt")
+	}
+
+	exists, _ = ffs.FileExists("non_existing_file.txt")
+	if exists {
+		t.Errorf("Not expected file %s, found", "non_existing_file.txt")
+	}
+}
+
+func TestFs_fileExistsAtDefault(t *testing.T) {
+	ffs := NewTestFileSystem()
+
+	var exists = ffs.FileExistsAt("existing_file.txt")
+	if !exists {
+		t.Errorf("Expected file %s, not found", "existing_file.txt")
+	}
+
+	exists = ffs.FileExistsAt("non_existing_file.txt")
+	if exists {
+		t.Errorf("Not expected file %s, found", "non_existing_file.txt")
+	}
+
+	exists = ffs.FileExistsAt("existing_dir")
+	if exists {
+		t.Errorf("Not expected file %s, found", "existing_dir")
+	}
+}
+
+func TestFs_directoryExistsDefault(t *testing.T) {
+	ffs := NewTestFileSystem()
+	var exists = ffs.DirectoryExistsAt("existing_dir")
+	if !exists {
+		t.Errorf("Expected file %s, not found", "existing_dir")
+	}
+
+	exists = ffs.DirectoryExistsAt("not_existing_dir")
+	if exists {
+		t.Errorf("Not expected file %s, found", "existing_dir")
+	}
+}
+
+func TestFs_DefaultBuilder(t *testing.T) {
+	ffs := DefaultFileSystem()
+	if ffs.ReadFile == nil ||
+		ffs.ReadDir == nil ||
+		ffs.DeleteFile == nil ||
+		ffs.FileExists == nil ||
+		ffs.Glob == nil ||
+		ffs.FileExistsAt == nil ||
+		ffs.DirectoryExistsAt == nil ||
+		ffs.Stat == nil ||
+		ffs.Getwd == nil ||
+		ffs.Chdir == nil ||
+		ffs.Abs == nil {
+		t.Errorf("Missing functions in DefaultFileSystem")
+	}
+}