Don't error maintenance commands on missing library clone folder

internal/command/modify/modify.go

@@ -164,18 +164,9 @@ func modifyRepositoryURL(newRepositoryURL string) error {
 	fmt.Printf("Changing URL of library %s from %s to %s\n", libraryName, oldRepositoryURL, newRepositoryURL)
 
 	// Remove the library Git clone folder. It will be cloned from the new URL on the next sync.
-	libraryRegistration := libraries.Repo{URL: libraryData.Repository}
-	gitCloneSubfolder, err := libraryRegistration.AsFolder()
-	if err != nil {
+	if err := libraries.BackupAndDeleteGitClone(config, &libraries.Repo{URL: libraryData.Repository}); err != nil {
 		return err
 	}
-	gitClonePath := paths.New(config.GitClonesFolder, gitCloneSubfolder)
-	if err := backup.Backup(gitClonePath); err != nil {
-		return fmt.Errorf("While backing up library's Git clone: %w", err)
-	}
-	if err := gitClonePath.RemoveAll(); err != nil {
-		return fmt.Errorf("While removing library's Git clone: %w", err)
-	}
 
 	// Update the library repository URL in the database.
 	libraryData.Repository = newRepositoryURL

internal/command/remove/remove.go

@@ -160,18 +160,9 @@ func removeLibrary(libraryName string) error {
 	}
 
 	// Remove the library Git clone folder.
-	libraryRegistration := libraries.Repo{URL: libraryData.Repository}
-	gitCloneSubfolder, err := libraryRegistration.AsFolder()
-	if err != nil {
+	if err := libraries.BackupAndDeleteGitClone(config, &libraries.Repo{URL: libraryData.Repository}); err != nil {
 		return err
 	}
-	gitClonePath := paths.New(config.GitClonesFolder, gitCloneSubfolder)
-	if err := backup.Backup(gitClonePath); err != nil {
-		return fmt.Errorf("While backing up library's Git clone: %w", err)
-	}
-	if err := gitClonePath.RemoveAll(); err != nil {
-		return fmt.Errorf("While removing library Git clone: %s", err)
-	}
 
 	return nil
 }

internal/libraries/repoclone.go

@@ -28,6 +28,10 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/arduino/go-paths-helper"
+	"github.com/arduino/libraries-repository-engine/internal/backup"
+	"github.com/arduino/libraries-repository-engine/internal/configuration"
+	"github.com/arduino/libraries-repository-engine/internal/feedback"
 	"github.com/arduino/libraries-repository-engine/internal/libraries/db"
 
 	"fmt"
@@ -134,3 +138,30 @@ func UpdateLibrary(release *db.Release, repoURL string, libraryDb *db.DB) error
 
 	return nil
 }
+
+// BackupAndDeleteGitClone backs up and then deletes the library's Git clone folder.
+func BackupAndDeleteGitClone(config *configuration.Config, repoMeta *Repo) error {
+	gitCloneSubfolder, err := repoMeta.AsFolder()
+	if err != nil {
+		return err
+	}
+	gitClonePath := paths.New(config.GitClonesFolder, gitCloneSubfolder)
+	// The library's clone folder may be removed by the sync process under expected circumstances.
+	// So its absence does not necessarily imply a problem.
+	gitClonePathExists, err := gitClonePath.ExistCheck()
+	if err != nil {
+		return err
+	}
+	if gitClonePathExists {
+		if err := backup.Backup(gitClonePath); err != nil {
+			return fmt.Errorf("While backing up library's Git clone: %w", err)
+		}
+		if err := gitClonePath.RemoveAll(); err != nil {
+			return fmt.Errorf("While removing library Git clone: %s", err)
+		}
+	} else {
+		feedback.Warningf("Library Git clone folder %s not present", gitClonePath)
+	}
+
+	return nil
+}

internal/libraries/repoclone_test.go

@@ -28,6 +28,10 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/arduino/go-paths-helper"
+	"github.com/arduino/libraries-repository-engine/internal/backup"
+	"github.com/arduino/libraries-repository-engine/internal/configuration"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -48,3 +52,38 @@ func TestCloneRepos(t *testing.T) {
 	_, err = os.Stat(repo.FolderPath)
 	require.NoError(t, err)
 }
+
+func TestBackupAndDeleteGitClone(t *testing.T) {
+	var err error
+
+	gitClonesFolder, err := paths.MkTempDir("", "libraries-test-testbackupanddeletegitclone")
+	require.NoError(t, err)
+	config := configuration.Config{
+		GitClonesFolder: gitClonesFolder.String(),
+	}
+	repoMeta := Repo{
+		URL: "https://github.com/Foo/Bar.git",
+	}
+
+	assert.Nil(t, BackupAndDeleteGitClone(&config, &repoMeta), "Return nil if library clone folder did not exist.")
+
+	gitCloneSubfolder, err := repoMeta.AsFolder()
+	require.NoError(t, err)
+	gitClonePath := paths.New(config.GitClonesFolder, gitCloneSubfolder)
+	err = gitClonePath.MkdirAll()
+	require.NoError(t, err)
+
+	assert.Nil(t, BackupAndDeleteGitClone(&config, &repoMeta), "Return nil if library clone folder did exist.")
+
+	exist, err := gitClonePath.ExistCheck()
+	require.NoError(t, err)
+
+	assert.False(t, exist, "Library clone folder was deleted.")
+
+	err = backup.Restore()
+	require.NoError(t, err)
+	exist, err = gitClonePath.ExistCheck()
+	require.NoError(t, err)
+
+	assert.True(t, exist, "Library clone folder was backed up.")
+}