Fix or workarond lint issues

This change mostly fixes golangci-lint's reported issues, except for

- Renaming ObjectId, since it will break existing code
- MapStructureHookFunc, since I'd like to separate larger refactoring
  from this commit.

Signed-off-by: Kazuyoshi Kato <[email protected]>

bson.go

@@ -39,10 +39,10 @@ func IsBSONObjectID(str string) bool {
 // ObjectId represents a BSON object ID (alias to go.mongodb.org/mongo-driver/bson/primitive.ObjectID)
 //
 // swagger:strfmt bsonobjectid
-type ObjectId bsonprim.ObjectID
+type ObjectId bsonprim.ObjectID //nolint:revive
 
 // NewObjectId creates a ObjectId from a Hex String
-func NewObjectId(hex string) ObjectId {
+func NewObjectId(hex string) ObjectId { //nolint:revive
 	oid, err := bsonprim.ObjectIDFromHex(hex)
 	if err != nil {
 		panic(err)

default_test.go

@@ -345,6 +345,8 @@ type testableFormat interface {
 }
 
 func testStringFormat(t *testing.T, what testableFormat, format, with string, validSamples, invalidSamples []string) {
+	t.Helper()
+
 	// text encoding interface
 	b := []byte(with)
 	err := what.UnmarshalText(b)
@@ -422,6 +424,8 @@ func testStringFormat(t *testing.T, what testableFormat, format, with string, va
 }
 
 func resetValue(t *testing.T, format string, what encoding.TextUnmarshaler) {
+	t.Helper()
+
 	err := what.UnmarshalText([]byte("reset value"))
 	assert.NoError(t, err)
 	val := reflect.Indirect(reflect.ValueOf(what))
@@ -430,13 +434,17 @@ func resetValue(t *testing.T, format string, what encoding.TextUnmarshaler) {
 }
 
 func testValid(t *testing.T, name, value string) {
+	t.Helper()
+
 	ok := Default.Validates(name, value)
 	if !ok {
 		t.Errorf("expected %q of type %s to be valid", value, name)
 	}
 }
 
 func testInvalid(t *testing.T, name, value string) {
+	t.Helper()
+
 	ok := Default.Validates(name, value)
 	if ok {
 		t.Errorf("expected %q of type %s to be invalid", value, name)

duration_test.go

@@ -75,6 +75,8 @@ func TestDuration(t *testing.T) {
 }
 
 func testDurationParser(t *testing.T, toParse string, expected time.Duration) {
+	t.Helper()
+
 	r, e := ParseDuration(toParse)
 	assert.NoError(t, e)
 	assert.Equal(t, expected, r)
@@ -91,6 +93,8 @@ func TestIsDuration_Failed(t *testing.T) {
 }
 
 func testDurationSQLScanner(t *testing.T, dur time.Duration) {
+	t.Helper()
+
 	values := []interface{}{int64(dur), float64(dur)}
 	for _, value := range values {
 		var result Duration

format.go

@@ -93,75 +93,80 @@ func NewSeededFormats(seeds []knownFormat, normalizer NameNormalizer) Registry {
 }
 
 // MapStructureHookFunc is a decode hook function for mapstructure
-func (f *defaultFormats) MapStructureHookFunc() mapstructure.DecodeHookFunc {
-	return func(from reflect.Type, to reflect.Type, data interface{}) (interface{}, error) {
+func (f *defaultFormats) MapStructureHookFunc() mapstructure.DecodeHookFunc { //nolint:gocyclo,cyclop
+	return func(from reflect.Type, to reflect.Type, obj interface{}) (interface{}, error) {
 		if from.Kind() != reflect.String {
-			return data, nil
+			return obj, nil
 		}
+		data, ok := obj.(string)
+		if !ok {
+			return nil, fmt.Errorf("failed to cast %+v to string", obj)
+		}
+
 		for _, v := range f.data {
 			tpe, _ := f.GetType(v.Name)
 			if to == tpe {
 				switch v.Name {
 				case "date":
-					d, err := time.Parse(RFC3339FullDate, data.(string))
+					d, err := time.Parse(RFC3339FullDate, data)
 					if err != nil {
 						return nil, err
 					}
 					return Date(d), nil
 				case "datetime":
-					input := data.(string)
+					input := data
 					if len(input) == 0 {
 						return nil, fmt.Errorf("empty string is an invalid datetime format")
 					}
 					return ParseDateTime(input)
 				case "duration":
-					dur, err := ParseDuration(data.(string))
+					dur, err := ParseDuration(data)
 					if err != nil {
 						return nil, err
 					}
 					return Duration(dur), nil
 				case "uri":
-					return URI(data.(string)), nil
+					return URI(data), nil
 				case "email":
-					return Email(data.(string)), nil
+					return Email(data), nil
 				case "uuid":
-					return UUID(data.(string)), nil
+					return UUID(data), nil
 				case "uuid3":
-					return UUID3(data.(string)), nil
+					return UUID3(data), nil
 				case "uuid4":
-					return UUID4(data.(string)), nil
+					return UUID4(data), nil
 				case "uuid5":
-					return UUID5(data.(string)), nil
+					return UUID5(data), nil
 				case "hostname":
-					return Hostname(data.(string)), nil
+					return Hostname(data), nil
 				case "ipv4":
-					return IPv4(data.(string)), nil
+					return IPv4(data), nil
 				case "ipv6":
-					return IPv6(data.(string)), nil
+					return IPv6(data), nil
 				case "cidr":
-					return CIDR(data.(string)), nil
+					return CIDR(data), nil
 				case "mac":
-					return MAC(data.(string)), nil
+					return MAC(data), nil
 				case "isbn":
-					return ISBN(data.(string)), nil
+					return ISBN(data), nil
 				case "isbn10":
-					return ISBN10(data.(string)), nil
+					return ISBN10(data), nil
 				case "isbn13":
-					return ISBN13(data.(string)), nil
+					return ISBN13(data), nil
 				case "creditcard":
-					return CreditCard(data.(string)), nil
+					return CreditCard(data), nil
 				case "ssn":
-					return SSN(data.(string)), nil
+					return SSN(data), nil
 				case "hexcolor":
-					return HexColor(data.(string)), nil
+					return HexColor(data), nil
 				case "rgbcolor":
-					return RGBColor(data.(string)), nil
+					return RGBColor(data), nil
 				case "byte":
-					return Base64(data.(string)), nil
+					return Base64(data), nil
 				case "password":
-					return Password(data.(string)), nil
+					return Password(data), nil
 				case "ulid":
-					ulid, err := ParseULID(data.(string))
+					ulid, err := ParseULID(data)
 					if err != nil {
 						return nil, err
 					}

ulid.go

@@ -32,7 +32,7 @@ var (
 	}
 
 	ULIDScanDefaultFunc = func(raw interface{}) (ULID, error) {
-		var u ULID = NewULIDZero()
+		u := NewULIDZero()
 		switch x := raw.(type) {
 		case nil:
 			// zerp ulid
@@ -90,7 +90,11 @@ func NewULIDZero() ULID {
 
 // NewULID generates new unique ULID value and a error if any
 func NewULID() (u ULID, err error) {
-	entropy := ulidEntropyPool.Get().(io.Reader)
+	obj := ulidEntropyPool.Get()
+	entropy, ok := obj.(io.Reader)
+	if !ok {
+		return u, fmt.Errorf("failed to cast %+v to io.Reader", obj)
+	}
 
 	id, err := ulid.New(ulid.Now(), entropy)
 	if err != nil {

ulid_test.go

@@ -195,7 +195,7 @@ func TestFormatULID_Scan(t *testing.T) {
 		assert.NoError(t, err)
 
 		ULIDScanOverrideFunc = func(raw interface{}) (ULID, error) {
-			var u ULID = NewULIDZero()
+			u := NewULIDZero()
 			switch x := raw.(type) {
 			case [16]byte:
 				return u, u.ULID.UnmarshalBinary(x[:])