Backup vendor at init

- Creates backup of vendor directory, if exists with content, at init.
- Adds tests for BackupVendor() function.
- Adds RemoveFile() function to test helper.

cmd/dep/init.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/golang/dep"
 	"github.com/golang/dep/internal"
@@ -72,6 +73,7 @@ func (cmd *initCommand) Run(ctx *dep.Ctx, args []string) error {
 
 	mf := filepath.Join(root, dep.ManifestName)
 	lf := filepath.Join(root, dep.LockName)
+	vpath := filepath.Join(root, "vendor")
 
 	mok, err := dep.IsRegular(mf)
 	if err != nil {
@@ -190,8 +192,17 @@ func (cmd *initCommand) Run(ctx *dep.Ctx, args []string) error {
 
 	l.Memo = s.HashInputs()
 
-	if ctx.Loggers.Verbose {
-		ctx.Loggers.Err.Println("dep: Writing manifest and lock files.")
+	// Pass timestamp (yyyyMMddHHmmss format) as suffix to backup name.
+	vendorbak, err := dep.BackupVendor(vpath, time.Now().Format("20060102150405"))
+	if err != nil {
+		return err
+	}
+	if vendorbak != "" {
+		ctx.loggers.Err.Printf("Old vendor backed up to %v", vendorbak)
+	}
+
+	if ctx.loggers.Verbose {
+		loggers.Err.Println("dep: Writing manifest and lock files.")
 	}
 
 	sw, err := dep.NewSafeWriter(m, nil, l, dep.VendorAlways)

internal/test/test.go

@@ -617,3 +617,10 @@ func (h *Helper) GetCommit(repo string) string {
 	}
 	return strings.TrimSpace(string(out))
 }
+
+func (h *Helper) RemoveFile(path string) {
+	err := os.RemoveAll(path)
+	if err != nil {
+		h.t.Fatalf("%+v", errors.Wrap(err, "could not remove file"))
+	}
+}

project.go

@@ -13,6 +13,7 @@ import (
 )
 
 var errProjectNotFound = fmt.Errorf("could not find project %s, use dep init to initiate a manifest", ManifestName)
+var errVendorBackupFailed = fmt.Errorf("Failed to create vendor backup")
 
 // findProjectRoot searches from the starting directory upwards looking for a
 // manifest file until we get to the root of the filesystem.
@@ -64,3 +65,28 @@ func (p *Project) MakeParams() gps.SolveParameters {
 
 	return params
 }
+
+// BackupVendor looks for existing vendor directory and if it's not empty,
+// creates a backup of it to a new directory with the provided suffix.
+func BackupVendor(vpath, suffix string) (string, error) {
+	// Check if there's a non-empty vendor directory
+	vendorExists, err := IsNonEmptyDir(vpath)
+	if err != nil {
+		return "", err
+	}
+	if vendorExists {
+		vendorbak := vpath + "-" + suffix
+		// Check if a directory with same name exists
+		if _, err = os.Stat(vendorbak); os.IsNotExist(err) {
+			// Copy existing vendor to vendor-{suffix}
+			if err := CopyDir(vpath, vendorbak); err != nil {
+				return "", err
+			}
+			return vendorbak, nil
+		} else {
+			return "", errVendorBackupFailed
+		}
+	}
+
+	return "", nil
+}

project_test.go

@@ -103,3 +103,62 @@ func TestSlashedGOPATH(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestBackupVendor(t *testing.T) {
+	h := test.NewHelper(t)
+	defer h.Cleanup()
+
+	pc := NewTestProjectContext(h, "vendorbackupproject")
+	defer pc.Release()
+
+	dummyFile := filepath.Join("vendor", "badinput_fileroot")
+	pc.CopyFile(dummyFile, "txn_writer/badinput_fileroot")
+	pc.Load()
+
+	if err := pc.VendorShouldExist(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Create a backup
+	wantName := "vendor-sfx"
+	vendorbak, err := BackupVendor("vendor", "sfx")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if vendorbak != wantName {
+		t.Fatalf("Vendor backup name is not as expected: \n\t(GOT) %v\n\t(WNT) %v", vendorbak, wantName)
+	}
+
+	if err = pc.h.ShouldExist(vendorbak); err != nil {
+		t.Fatal(err)
+	}
+
+	if err = pc.h.ShouldExist(vendorbak + string(filepath.Separator) + "badinput_fileroot"); err != nil {
+		t.Fatal(err)
+	}
+
+	// Should return error on creating backup with existing filename
+	vendorbak, err = BackupVendor("vendor", "sfx")
+
+	if err != errVendorBackupFailed {
+		t.Fatalf("Vendor backup error is not as expected: \n\t(GOT) %v\n\t(WNT) %v", err, errVendorBackupFailed)
+	}
+
+	if vendorbak != "" {
+		t.Fatalf("Vendor backup name is not as expected: \n\t(GOT) %v\n\t(WNT) %v", vendorbak, "")
+	}
+
+	// Delete vendor
+	pc.h.RemoveFile("vendor")
+
+	// Should return empty backup file name when no vendor exists
+	vendorbak, err = BackupVendor("vendor", "sfx")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if vendorbak != "" {
+		t.Fatalf("Vendor backup name is not as expected: \n\t(GOT) %v\n\t(WNT) %v", vendorbak, "")
+	}
+}