diff --git a/formatter_test.go b/formatter_test.go
deleted file mode 100644
index f5496ed..0000000
--- a/formatter_test.go
+++ /dev/null
@@ -1,106 +0,0 @@
-package slogformatter
-
-import (
-	"context"
-	"log/slog"
-	"sync/atomic"
-	"testing"
-	"time"
-
-	slogmock "github.com/samber/slog-mock"
-	"github.com/stretchr/testify/assert"
-)
-
-func TestFormatByKind(t *testing.T) {
-	t.Parallel()
-	is := assert.New(t)
-
-	handler := NewFormatterMiddleware(
-		FormatByKind(slog.KindDuration, func(v slog.Value) slog.Value {
-			return slog.StringValue(v.Duration().String())
-		}),
-	)
-
-	var checked int32
-
-	logger := slog.New(
-		handler(
-			slogmock.Option{
-				Handle: func(ctx context.Context, record slog.Record) error {
-					is.Equal("hello world", record.Message)
-
-					attrs := map[string]slog.Value{}
-					record.Attrs(func(attr slog.Attr) bool {
-						attrs[attr.Key] = attr.Value
-						return true
-					})
-
-					is.Len(attrs, 2)
-					is.Equal(attrs["key"], slog.StringValue("value"))
-					is.Equal(attrs["subgroup"].Kind(), slog.KindGroup)
-					is.Equal(attrs["subgroup"].Group()[0].Key, "duration")
-					is.Equal(attrs["subgroup"].Group()[0].Value, slog.StringValue("1s"))
-
-					atomic.AddInt32(&checked, 1)
-					return nil
-				},
-			}.NewMockHandler(),
-		),
-	)
-
-	logger.Info("hello world",
-		slog.String("key", "value"),
-		slog.Group("subgroup",
-			slog.Duration("duration", 1*time.Second),
-		),
-	)
-
-	is.Equal(int32(1), atomic.LoadInt32(&checked))
-}
-
-func TestFormatByKey(t *testing.T) {
-	t.Parallel()
-	is := assert.New(t)
-
-	handler := NewFormatterMiddleware(
-		FormatByKey("duration", func(v slog.Value) slog.Value {
-			return slog.StringValue(v.Duration().String())
-		}),
-	)
-
-	var checked int32
-
-	logger := slog.New(
-		handler(
-			slogmock.Option{
-				Handle: func(ctx context.Context, record slog.Record) error {
-					is.Equal("hello world", record.Message)
-
-					attrs := map[string]slog.Value{}
-					record.Attrs(func(attr slog.Attr) bool {
-						attrs[attr.Key] = attr.Value
-						return true
-					})
-
-					is.Len(attrs, 2)
-					is.Equal(attrs["key"], slog.StringValue("value"))
-					is.Equal(attrs["subgroup"].Kind(), slog.KindGroup)
-					is.Equal(attrs["subgroup"].Group()[0].Key, "duration")
-					is.Equal(attrs["subgroup"].Group()[0].Value, slog.StringValue("1s"))
-
-					atomic.AddInt32(&checked, 1)
-					return nil
-				},
-			}.NewMockHandler(),
-		),
-	)
-
-	logger.Info("hello world",
-		slog.String("key", "value"),
-		slog.Group("subgroup",
-			slog.Duration("duration", 1*time.Second),
-		),
-	)
-
-	is.Equal(int32(1), atomic.LoadInt32(&checked))
-}
diff --git a/go.mod b/go.mod
index becd74f..e422493 100644
--- a/go.mod
+++ b/go.mod
@@ -4,17 +4,6 @@ go 1.21
 
 require github.com/samber/slog-multi v1.3.3
 
-require (
-	github.com/samber/lo v1.47.0
-	github.com/samber/slog-mock v0.1.0
-	github.com/stretchr/testify v1.10.0
-	go.uber.org/goleak v1.3.0
-)
+require github.com/samber/lo v1.47.0
 
-require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/kr/text v0.2.0 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/text v0.18.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
-)
+require golang.org/x/text v0.18.0 // indirect
diff --git a/go.sum b/go.sum
index 6df69ff..19050f4 100644
--- a/go.sum
+++ b/go.sum
@@ -1,26 +1,6 @@
-github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
-github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
-github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
-github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/samber/lo v1.47.0 h1:z7RynLwP5nbyRscyvcD043DWYoOcYRv3mV8lBeqOCLc=
 github.com/samber/lo v1.47.0/go.mod h1:RmDH9Ct32Qy3gduHQuKJ3gW1fMHAnE/fAzQuf6He5cU=
-github.com/samber/slog-mock v0.1.0 h1:I3PApMma8+qoxrfh/MoTmHAWTN8CZyrOKAn1FXus7zU=
-github.com/samber/slog-mock v0.1.0/go.mod h1:muKl65H9go1idsAoiDnetK/8pIQY/1X760/UwGD+REI=
 github.com/samber/slog-multi v1.3.3 h1:qhFXaYdW73FIWLt8SrXMXfPwY58NpluzKDwRdPvhWWY=
 github.com/samber/slog-multi v1.3.3/go.mod h1:ACuZ5B6heK57TfMVkVknN2UZHoFfjCwRxR0Q2OXKHlo=
-github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
-github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
-go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 golang.org/x/text v0.18.0 h1:XvMDiNzPAl0jr17s6W9lcaIhGUfUORdGCNsuLmPG224=
 golang.org/x/text v0.18.0/go.mod h1:BuEKDfySbSR4drPmRPG/7iBdf8hvFMuRexcpahXilzY=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/main_test.go b/main_test.go
deleted file mode 100644
index 381acc8..0000000
--- a/main_test.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package slogformatter
-
-import (
-	"testing"
-
-	"go.uber.org/goleak"
-)
-
-func TestMain(m *testing.M) {
-	goleak.VerifyTestMain(m)
-}