feat: migration command

pkg/commands/internal/migrate/fakeloader/config.go

@@ -0,0 +1,22 @@
+package fakeloader
+
+// Config implements [config.BaseConfig].
+// This only the stub for the real file loader.
+type Config struct {
+	Version string `mapstructure:"version"`
+
+	cfgDir string // Path to the directory containing golangci-lint config file.
+}
+
+func NewConfig() *Config {
+	return &Config{}
+}
+
+// SetConfigDir sets the path to directory that contains golangci-lint config file.
+func (c *Config) SetConfigDir(dir string) {
+	c.cfgDir = dir
+}
+
+func (*Config) IsInternalTest() bool {
+	return false
+}

pkg/commands/internal/migrate/fakeloader/fakeloader.go

@@ -0,0 +1,48 @@
+package fakeloader
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/go-viper/mapstructure/v2"
+
+	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/parser"
+	"github.com/golangci/golangci-lint/pkg/config"
+)
+
+// Load is used to keep case of configuration.
+// Viper serialize raw map keys in lowercase, this is a problem with the configuration of some linters.
+func Load(srcPath string, old any) error {
+	file, err := os.Open(srcPath)
+	if err != nil {
+		return fmt.Errorf("open file: %w", err)
+	}
+
+	defer func() { _ = file.Close() }()
+
+	raw := map[string]any{}
+
+	err = parser.Decode(file, raw)
+	if err != nil {
+		return err
+	}
+
+	// NOTE: this is inspired by viper internals.
+	cc := &mapstructure.DecoderConfig{
+		Result:           old,
+		WeaklyTypedInput: true,
+		DecodeHook:       config.DecodeHookFunc(),
+	}
+
+	decoder, err := mapstructure.NewDecoder(cc)
+	if err != nil {
+		return fmt.Errorf("constructing mapstructure decoder: %w", err)
+	}
+
+	err = decoder.Decode(raw)
+	if err != nil {
+		return fmt.Errorf("decoding configuration file: %w", err)
+	}
+
+	return nil
+}

pkg/commands/internal/migrate/migrate_test.go

@@ -8,16 +8,27 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/spf13/viper"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"gopkg.in/yaml.v3"
 
+	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/fakeloader"
+	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/parser"
 	"github.com/golangci/golangci-lint/pkg/commands/internal/migrate/versionone"
-	"github.com/golangci/golangci-lint/pkg/config"
-	"github.com/golangci/golangci-lint/pkg/logutils"
 )
 
+type fakeFile struct {
+	bytes.Buffer
+	name string
+}
+
+func newFakeFile(name string) *fakeFile {
+	return &fakeFile{name: name}
+}
+
+func (f *fakeFile) Name() string {
+	return f.name
+}
+
 func TestToConfig(t *testing.T) {
 	var testFiles []string
 
@@ -30,7 +41,7 @@ func TestToConfig(t *testing.T) {
 			return nil
 		}
 
-		if strings.HasSuffix(path, ".golden.yml") {
+		if strings.Contains(path, ".golden.") {
 			return nil
 		}
 
@@ -46,7 +57,7 @@ func TestToConfig(t *testing.T) {
 			t.Parallel()
 
 			ext := filepath.Ext(fileIn)
-			fileGolden := strings.TrimSuffix(fileIn, ext) + ".golden.yml"
+			fileGolden := strings.TrimSuffix(fileIn, ext) + ".golden" + ext
 
 			testFile(t, fileIn, fileGolden, false)
 		})
@@ -58,30 +69,33 @@ func testFile(t *testing.T, in, golden string, update bool) {
 
 	old := versionone.NewConfig()
 
-	options := config.LoaderOptions{Config: in}
-
 	// Fake load of the configuration.
 	// IMPORTANT: The default values from flags are not set.
-	loader := config.NewBaseLoader(logutils.NewStderrLog("skip"), viper.New(), options, old, nil)
-
-	err := loader.Load()
+	err := fakeloader.Load(in, old)
 	require.NoError(t, err)
 
 	if update {
 		updateGolden(t, golden, old)
 	}
 
-	expected, err := os.ReadFile(golden)
-	require.NoError(t, err)
+	buf := newFakeFile("test" + filepath.Ext(golden))
 
-	var buf bytes.Buffer
-	encoder := yaml.NewEncoder(&buf)
-	encoder.SetIndent(2)
+	err = parser.Encode(ToConfig(old), buf)
+	require.NoError(t, err)
 
-	err = encoder.Encode(ToConfig(old))
+	expected, err := os.ReadFile(golden)
 	require.NoError(t, err)
 
-	assert.YAMLEq(t, string(expected), buf.String())
+	switch filepath.Ext(golden) {
+	case ".yml":
+		assert.YAMLEq(t, string(expected), buf.String())
+	case ".json":
+		assert.JSONEq(t, string(expected), buf.String())
+	case ".toml":
+		assert.Equal(t, string(expected), buf.String())
+	default:
+		require.Failf(t, "unsupported extension: %s", golden)
+	}
 }
 
 func updateGolden(t *testing.T, golden string, old *versionone.Config) {
@@ -94,9 +108,6 @@ func updateGolden(t *testing.T, golden string, old *versionone.Config) {
 		_ = fileOut.Close()
 	}()
 
-	encoder := yaml.NewEncoder(fileOut)
-	encoder.SetIndent(2)
-
-	err = encoder.Encode(ToConfig(old))
+	err = parser.Encode(ToConfig(old), fileOut)
 	require.NoError(t, err)
 }

pkg/commands/internal/migrate/parser/parser.go

@@ -0,0 +1,87 @@
+package parser
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"path/filepath"
+	"strings"
+
+	"github.com/pelletier/go-toml/v2"
+	"gopkg.in/yaml.v3"
+)
+
+type File interface {
+	io.ReadWriter
+	Name() string
+}
+
+// Decode decodes a file into data.
+// The choice of the decoder is based on the file extension.
+func Decode(file File, data any) error {
+	ext := filepath.Ext(file.Name())
+
+	switch strings.ToLower(ext) {
+	case ".yaml", ".yml", ".json":
+		err := yaml.NewDecoder(file).Decode(data)
+		if err != nil && !errors.Is(err, io.EOF) {
+			return fmt.Errorf("YAML decode file %s: %w", file.Name(), err)
+		}
+
+	case ".toml":
+		err := toml.NewDecoder(file).Decode(&data)
+		if err != nil {
+			return fmt.Errorf("TOML decode file %s: %w", file.Name(), err)
+		}
+
+	default:
+		return fmt.Errorf("unsupported file type: %s", ext)
+	}
+
+	return nil
+}
+
+// Encode encodes data into a file.
+// The choice of the encoder is based on the file extension.
+func Encode(data any, dstFile File) error {
+	ext := filepath.Ext(dstFile.Name())
+
+	switch strings.ToLower(ext) {
+	case ".yml", ".yaml":
+		encoder := yaml.NewEncoder(dstFile)
+		encoder.SetIndent(2)
+
+		return encoder.Encode(data)
+
+	case ".toml":
+		encoder := toml.NewEncoder(dstFile)
+
+		return encoder.Encode(data)
+
+	case ".json":
+		// The JSON encoder converts empty struct to `{}` instead of nothing (even with omitempty JSON struct tags).
+		// So we need to use the YAML encoder as bridge to create JSON file.
+
+		var buf bytes.Buffer
+		err := yaml.NewEncoder(&buf).Encode(data)
+		if err != nil {
+			return err
+		}
+
+		raw := map[string]any{}
+		err = yaml.NewDecoder(&buf).Decode(raw)
+		if err != nil {
+			return err
+		}
+
+		encoder := json.NewEncoder(dstFile)
+		encoder.SetIndent("", "  ")
+
+		return encoder.Encode(raw)
+
+	default:
+		return fmt.Errorf("unsupported file type: %s", ext)
+	}
+}

pkg/commands/internal/migrate/testdata/empty.golden.json

@@ -0,0 +1,18 @@
+{
+  "formatters": {
+    "exclusions": {
+      "generated": "lax"
+    }
+  },
+  "linters": {
+    "exclusions": {
+      "generated": "lax",
+      "paths": [
+        "third_party$",
+        "builtin$",
+        "examples$"
+      ]
+    }
+  },
+  "version": "2"
+}

pkg/commands/internal/migrate/testdata/empty.golden.toml

@@ -0,0 +1,10 @@
+version = '2'
+
+[linters]
+[linters.exclusions]
+generated = 'lax'
+paths = ['third_party$', 'builtin$', 'examples$']
+
+[formatters]
+[formatters.exclusions]
+generated = 'lax'

pkg/commands/internal/migrate/testdata/linters-settings_gocritic.golden.yml

@@ -231,35 +231,35 @@ linters:
         - experimental
         - opinionated
       settings:
-        captlocal:
-          paramsonly: false
-        commentedoutcode:
-          minlength: 50
+        captLocal:
+          paramsOnly: false
+        commentedOutCode:
+          minLength: 50
         elseif:
-          skipbalanced: false
-        hugeparam:
-          sizethreshold: 70
-        ifelsechain:
-          minthreshold: 4
-        nestingreduce:
-          bodywidth: 4
-        rangeexprcopy:
-          sizethreshold: 516
-          skiptestfuncs: false
-        rangevalcopy:
-          sizethreshold: 32
-          skiptestfuncs: false
+          skipBalanced: false
+        hugeParam:
+          sizeThreshold: 70
+        ifElseChain:
+          minThreshold: 4
+        nestingReduce:
+          bodyWidth: 4
+        rangeExprCopy:
+          sizeThreshold: 516
+          skipTestFuncs: false
+        rangeValCopy:
+          sizeThreshold: 32
+          skipTestFuncs: false
         ruleguard:
           debug: emptyDecl
           disable: myGroupName,#myTagName
           enable: myGroupName,#myTagName
-          failon: dsl,import
+          failOn: dsl,import
           rules: ${base-path}/ruleguard/rules-*.go,${base-path}/myrule1.go
-        toomanyresultschecker:
-          maxresults: 10
-        truncatecmp:
-          skiparchdependent: false
+        tooManyResultsChecker:
+          maxResults: 10
+        truncateCmp:
+          skipArchDependent: false
         underef:
-          skiprecvderef: false
-        unnamedresult:
-          checkexported: true
+          skipRecvDeref: false
+        unnamedResult:
+          checkExported: true

pkg/commands/internal/migrate/testdata/linters-settings_goheader.golden.yml

@@ -4,9 +4,9 @@ linters:
     goheader:
       values:
         const:
-          company: MY COMPANY
+          COMPANY: MY COMPANY
         regexp:
-          author: .*@mycompany\.com
+          AUTHOR: .*@mycompany\.com
       template: |-
         Put here copyright header template for source code files
         For example:

pkg/commands/internal/migrate/testdata/linters-settings_gosec.golden.yml

@@ -87,20 +87,20 @@ linters:
       severity: medium
       confidence: medium
       config:
-        g101:
+        G101:
           entropy_threshold: "80.0"
           ignore_entropy: false
           pattern: (?i)example
           per_char_threshold: "3.0"
           truncate: "32"
-        g104:
+        G104:
           fmt:
             - Fscanf
-        g111:
+        G111:
           pattern: custom\.Dir\(\)
-        g301: "0750"
-        g302: "0600"
-        g306: "0600"
+        G301: "0750"
+        G302: "0600"
+        G306: "0600"
         global:
           '#nosec': '#my-custom-nosec'
           audit: true