Allow forced v3 migration with existing v3 usage

cmd/internal/migrations/common.go

@@ -5,24 +5,22 @@ import (
 	"os"
 	"regexp"
 	"strconv"
-	"strings"
 
 	semver "github.com/Masterminds/semver/v3"
 	"github.com/spf13/cobra"
 
 	"github.com/gofiber/cli/cmd/internal"
 )
 
-var pkgRegex = regexp.MustCompile(`(github\.com\/gofiber\/fiber\/)(v\d+)( *?)(v[\w.-]+)`)
-
-func MigrateGoPkgs(cmd *cobra.Command, cwd string, curr, target *semver.Version) error {
-	pkgReplacer := strings.NewReplacer(
-		"github.com/gofiber/fiber/v"+strconv.FormatUint(curr.Major(), 10),
-		"github.com/gofiber/fiber/v"+strconv.FormatUint(target.Major(), 10),
-	)
+var (
+	pkgRegex       = regexp.MustCompile(`(github\.com/gofiber/fiber/)(v\d+)( *?)(v[\w.-]+)`)
+	pkgImportRegex = regexp.MustCompile(`(?m)^(\s*(?:[\w.]+\s+)?")github\.com/gofiber/fiber/v\d+("$)`)
+)
 
+func MigrateGoPkgs(cmd *cobra.Command, cwd string, _, target *semver.Version) error {
 	err := internal.ChangeFileContent(cwd, func(content string) string {
-		return pkgReplacer.Replace(content)
+		replacement := fmt.Sprintf("${1}github.com/gofiber/fiber/v%d${2}", target.Major())
+		return pkgImportRegex.ReplaceAllString(content, replacement)
 	})
 	if err != nil {
 		return fmt.Errorf("failed to migrate Go packages: %w", err)

cmd/migrate.go

@@ -78,7 +78,18 @@ func migrateRunE(cmd *cobra.Command, opts MigrateOptions) error {
 		return fmt.Errorf("cannot get current working directory: %w", err)
 	}
 
-	err = migrations.DoMigration(cmd, wd, currentVersion, targetVersion)
+	migrateFrom := currentVersion
+	migrateFromS := currentVersionS
+	if opts.Force && !targetVersion.GreaterThan(currentVersion) {
+		prevMajor := targetVersion.Major() - 1
+		migrateFrom, err = semver.NewVersion(fmt.Sprintf("%d.0.0", prevMajor))
+		if err != nil {
+			return fmt.Errorf("invalid previous major version %d: %w", prevMajor, err)
+		}
+		migrateFromS = migrateFrom.String()
+	}
+
+	err = migrations.DoMigration(cmd, wd, migrateFrom, targetVersion)
 	if err != nil {
 		return fmt.Errorf("migration failed %w", err)
 	}
@@ -89,7 +100,7 @@ func migrateRunE(cmd *cobra.Command, opts MigrateOptions) error {
 		}
 	}
 
-	msg := fmt.Sprintf("Migration from Fiber %s to %s", currentVersionS, opts.TargetVersionS)
+	msg := fmt.Sprintf("Migration from Fiber %s to %s", migrateFromS, opts.TargetVersionS)
 	cmd.Println(termenv.String(msg).
 		Foreground(termenv.ANSIBrightBlue))
 

cmd/migrate_test.go

@@ -177,7 +177,8 @@ require github.com/gofiber/fiber/v3 v3.0.0
 		cmd := newMigrateCmd()
 		out, err := runCobraCmd(cmd, "-t=3.0.0", "-f")
 		require.NoError(t, err)
-		assert.Contains(t, out, "Migration from Fiber 3.0.0 to 3.0.0")
+		assert.Contains(t, out, "Migration from Fiber 2.0.0 to 3.0.0")
+		assert.Contains(t, out, "Migrating Go packages")
 		assert.Len(t, cmds, 3)
 	})
 
@@ -196,7 +197,42 @@ require github.com/gofiber/fiber/v3 v3.0.0
 		cmd := newMigrateCmd()
 		out, err := runCobraCmd(cmd, "-t=3.0.0", "-f", "-s")
 		require.NoError(t, err)
-		assert.Contains(t, out, "Migration from Fiber 3.0.0 to 3.0.0")
+		assert.Contains(t, out, "Migration from Fiber 2.0.0 to 3.0.0")
+		assert.Contains(t, out, "Migrating Go packages")
 		assert.Empty(t, cmds)
 	})
 }
+
+func Test_Migrate_ForcePartialV3(t *testing.T) {
+	dir := t.TempDir()
+
+	gomod := `module example
+
+go 1.20
+
+require github.com/gofiber/fiber/v3 v3.0.0
+`
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "go.mod"), []byte(gomod), 0o600))
+
+	main := `package main
+import "github.com/gofiber/fiber/v2"
+func main() {}`
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "main.go"), []byte(main), 0o600))
+
+	cwd, err := os.Getwd()
+	require.NoError(t, err)
+	require.NoError(t, os.Chdir(dir))
+	defer func() { require.NoError(t, os.Chdir(cwd)) }()
+
+	cmd := newMigrateCmd()
+	setupCmd()
+	defer teardownCmd()
+	out, err := runCobraCmd(cmd, "-t=3.0.0", "-f")
+	require.NoError(t, err)
+	assert.Contains(t, out, "Migration from Fiber 2.0.0 to 3.0.0")
+	assert.Contains(t, out, "Migrating Go packages")
+
+	content := readFileTB(t, filepath.Join(dir, "main.go"))
+	assert.Contains(t, content, "github.com/gofiber/fiber/v3")
+	assert.NotContains(t, content, "github.com/gofiber/fiber/v2")
+}