test: default file system

Author: mlataza

internal/utils/filesystem.go

@@ -26,3 +26,27 @@ func CreateFolderIfMissing(dir string) error {
 
 	return nil
 }
+
+type FileSystem interface {
+	Executable() (string, error)
+	ReadFile(name string) ([]byte, error)
+	WriteFile(name string, data []byte, perm os.FileMode) error
+}
+
+type defaultFileSystem struct{}
+
+func (*defaultFileSystem) Executable() (string, error) {
+	return os.Executable()
+}
+
+func (*defaultFileSystem) ReadFile(name string) ([]byte, error) {
+	return os.ReadFile(name)
+}
+
+func (*defaultFileSystem) WriteFile(name string, data []byte, perm os.FileMode) error {
+	return os.WriteFile(name, data, perm)
+}
+
+func NewFileSystem() FileSystem {
+	return &defaultFileSystem{}
+}

internal/utils/filesystem_test.go

@@ -1,6 +1,7 @@
 package utils
 
 import (
+	"os"
 	"path/filepath"
 	"testing"
 )
@@ -19,6 +20,19 @@ func TestDirExists(t *testing.T) {
 	}
 }
 
+func TestDirExists_File(t *testing.T) {
+	tmpDir := t.TempDir()
+	filePath := filepath.Join(tmpDir, "file.txt")
+
+	if err := os.WriteFile(filePath, []byte("data"), DefaultFileMod); err != nil {
+		t.Fatal(err)
+	}
+
+	if DirExists(filePath) {
+		t.Errorf("expected false for a file path, got true")
+	}
+}
+
 func TestCreateFolderIfMissing(t *testing.T) {
 	tmpDir := t.TempDir()
 	newDir := filepath.Join(tmpDir, "new_folder")
@@ -39,3 +53,74 @@ func TestCreateFolderIfMissing(t *testing.T) {
 		t.Fatalf("expected no error, got %v", err)
 	}
 }
+
+// defaultFileSystem tests
+
+func TestNewFileSystem_ReturnsNonNil(t *testing.T) {
+	fs := NewFileSystem()
+	if fs == nil {
+		t.Fatal("expected non-nil FileSystem")
+	}
+}
+
+func TestDefaultFileSystem_Executable(t *testing.T) {
+	fs := NewFileSystem()
+
+	path, err := fs.Executable()
+
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if path == "" {
+		t.Error("expected non-empty executable path")
+	}
+}
+
+func TestDefaultFileSystem_WriteFile(t *testing.T) {
+	fs := NewFileSystem()
+	filePath := filepath.Join(t.TempDir(), "test.txt")
+	data := []byte("hello")
+
+	err := fs.WriteFile(filePath, data, DefaultFileMod)
+
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+
+	got, err := os.ReadFile(filePath)
+	if err != nil {
+		t.Fatalf("failed to read back file: %v", err)
+	}
+	if string(got) != string(data) {
+		t.Errorf("expected %q, got %q", data, got)
+	}
+}
+
+func TestDefaultFileSystem_ReadFile(t *testing.T) {
+	fs := NewFileSystem()
+	filePath := filepath.Join(t.TempDir(), "test.txt")
+	data := []byte("hello")
+
+	if err := os.WriteFile(filePath, data, DefaultFileMod); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := fs.ReadFile(filePath)
+
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if string(got) != string(data) {
+		t.Errorf("expected %q, got %q", data, got)
+	}
+}
+
+func TestDefaultFileSystem_ReadFile_NotFound(t *testing.T) {
+	fs := NewFileSystem()
+
+	_, err := fs.ReadFile(filepath.Join(t.TempDir(), "nonexistent.txt"))
+
+	if err == nil {
+		t.Error("expected error reading nonexistent file, got nil")
+	}
+}