diff --git a/go.mod b/go.mod
index eab2aac97..60b751726 100644
--- a/go.mod
+++ b/go.mod
@@ -51,7 +51,6 @@ require (
 	github.com/joyent/triton-go v0.0.0-20180313100802-d8f9c0314926
 	github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0
 	github.com/lib/pq v1.10.3
-	github.com/likexian/gokit v0.20.15
 	github.com/lusis/go-artifactory v0.0.0-20160115162124-7e4ce345df82
 	github.com/masterzen/winrm v0.0.0-20200615185753-c42b5136ff88
 	github.com/mattn/go-isatty v0.0.12
diff --git a/go.sum b/go.sum
index e14e6617a..7d2eaf941 100644
--- a/go.sum
+++ b/go.sum
@@ -460,14 +460,6 @@ github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/lib/pq v1.10.3 h1:v9QZf2Sn6AmjXtQeFpdoq/eaNtYP6IN+7lcrygsIAtg=
 github.com/lib/pq v1.10.3/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
-github.com/likexian/gokit v0.0.0-20190309162924-0a377eecf7aa/go.mod h1:QdfYv6y6qPA9pbBA2qXtoT8BMKha6UyNbxWGWl/9Jfk=
-github.com/likexian/gokit v0.0.0-20190418170008-ace88ad0983b/go.mod h1:KKqSnk/VVSW8kEyO2vVCXoanzEutKdlBAPohmGXkxCk=
-github.com/likexian/gokit v0.0.0-20190501133040-e77ea8b19cdc/go.mod h1:3kvONayqCaj+UgrRZGpgfXzHdMYCAO0KAt4/8n0L57Y=
-github.com/likexian/gokit v0.20.15 h1:DgtIqqTRFqtbiLJFzuRESwVrxWxfs8OlY6hnPYBa3BM=
-github.com/likexian/gokit v0.20.15/go.mod h1:kn+nTv3tqh6yhor9BC4Lfiu58SmH8NmQ2PmEl+uM6nU=
-github.com/likexian/simplejson-go v0.0.0-20190409170913-40473a74d76d/go.mod h1:Typ1BfnATYtZ/+/shXfFYLrovhFyuKvzwrdOnIDHlmg=
-github.com/likexian/simplejson-go v0.0.0-20190419151922-c1f9f0b4f084/go.mod h1:U4O1vIJvIKwbMZKUJ62lppfdvkCdVd2nfMimHK81eec=
-github.com/likexian/simplejson-go v0.0.0-20190502021454-d8787b4bfa0b/go.mod h1:3BWwtmKP9cXWwYCr5bkoVDEfLywacOv0s06OBEDpyt8=
 github.com/lusis/go-artifactory v0.0.0-20160115162124-7e4ce345df82 h1:wnfcqULT+N2seWf6y4yHzmi7GD2kNx4Ute0qArktD48=
 github.com/lusis/go-artifactory v0.0.0-20160115162124-7e4ce345df82/go.mod h1:y54tfGmO3NKssKveTEFFzH8C/akrSOy/iW9qEAUDV84=
 github.com/mailru/easyjson v0.0.0-20160728113105-d5b7844b561a/go.mod h1:C1wdFJiN94OJF2b5HbByQZoLdCWB1Yqtg26g4irojpc=
diff --git a/internal/backend/remote-state/cos/backend_state.go b/internal/backend/remote-state/cos/backend_state.go
index c9df2a6c1..ab92cfb7c 100644
--- a/internal/backend/remote-state/cos/backend_state.go
+++ b/internal/backend/remote-state/cos/backend_state.go
@@ -11,7 +11,6 @@ import (
 	"github.com/hashicorp/terraform/internal/states"
 	"github.com/hashicorp/terraform/internal/states/remote"
 	"github.com/hashicorp/terraform/internal/states/statemgr"
-	"github.com/likexian/gokit/assert"
 )
 
 // Define file suffix
@@ -88,7 +87,15 @@ func (b *Backend) StateMgr(name string) (statemgr.Full, error) {
 		return nil, err
 	}
 
-	if !assert.IsContains(ws, name) {
+	exists := false
+	for _, candidate := range ws {
+		if candidate == name {
+			exists = true
+			break
+		}
+	}
+
+	if !exists {
 		log.Printf("[DEBUG] workspace %v not exists", name)
 
 		// take a lock on this state while we write it
diff --git a/internal/backend/remote-state/cos/backend_test.go b/internal/backend/remote-state/cos/backend_test.go
index f527d4a5a..eb9038ff3 100644
--- a/internal/backend/remote-state/cos/backend_test.go
+++ b/internal/backend/remote-state/cos/backend_test.go
@@ -9,7 +9,6 @@ import (
 
 	"github.com/hashicorp/terraform/internal/backend"
 	"github.com/hashicorp/terraform/internal/states/remote"
-	"github.com/likexian/gokit/assert"
 )
 
 const (
@@ -38,12 +37,18 @@ func TestStateFile(t *testing.T) {
 	}
 
 	for _, c := range cases {
-		b := &Backend{
-			prefix: c.prefix,
-			key:    c.key,
-		}
-		assert.Equal(t, b.stateFile(c.stateName), c.wantStateFile)
-		assert.Equal(t, b.lockFile(c.stateName), c.wantLockFile)
+		t.Run(fmt.Sprintf("%s %s %s", c.prefix, c.key, c.stateName), func(t *testing.T) {
+			b := &Backend{
+				prefix: c.prefix,
+				key:    c.key,
+			}
+			if got, want := b.stateFile(c.stateName), c.wantStateFile; got != want {
+				t.Errorf("wrong state file name\ngot:  %s\nwant: %s", got, want)
+			}
+			if got, want := b.lockFile(c.stateName), c.wantLockFile; got != want {
+				t.Errorf("wrong lock file name\ngot:  %s\nwant: %s", got, want)
+			}
+		})
 	}
 }
 
@@ -56,10 +61,14 @@ func TestRemoteClient(t *testing.T) {
 	defer teardownBackend(t, be)
 
 	ss, err := be.StateMgr(backend.DefaultStateName)
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	rs, ok := ss.(*remote.State)
-	assert.True(t, ok)
+	if !ok {
+		t.Fatalf("wrong state manager type\ngot:  %T\nwant: %T", ss, rs)
+	}
 
 	remote.TestClient(t, rs.Client)
 }
@@ -74,10 +83,14 @@ func TestRemoteClientWithPrefix(t *testing.T) {
 	defer teardownBackend(t, be)
 
 	ss, err := be.StateMgr(backend.DefaultStateName)
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	rs, ok := ss.(*remote.State)
-	assert.True(t, ok)
+	if !ok {
+		t.Fatalf("wrong state manager type\ngot:  %T\nwant: %T", ss, rs)
+	}
 
 	remote.TestClient(t, rs.Client)
 }
@@ -91,10 +104,14 @@ func TestRemoteClientWithEncryption(t *testing.T) {
 	defer teardownBackend(t, be)
 
 	ss, err := be.StateMgr(backend.DefaultStateName)
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	rs, ok := ss.(*remote.State)
-	assert.True(t, ok)
+	if !ok {
+		t.Fatalf("wrong state manager type\ngot:  %T\nwant: %T", ss, rs)
+	}
 
 	remote.TestClient(t, rs.Client)
 }
@@ -122,10 +139,14 @@ func TestRemoteLocks(t *testing.T) {
 	}
 
 	c0, err := remoteClient()
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	c1, err := remoteClient()
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	remote.TestRemoteLocks(t, c0, c1)
 }
@@ -203,10 +224,14 @@ func setupBackend(t *testing.T, bucket, prefix, key string, encrypt bool) backen
 	be := b.(*Backend)
 
 	c, err := be.client("tencentcloud")
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	err = c.putBucket()
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	return b
 }
@@ -215,10 +240,14 @@ func teardownBackend(t *testing.T, b backend.Backend) {
 	t.Helper()
 
 	c, err := b.(*Backend).client("tencentcloud")
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 
 	err = c.deleteBucket(true)
-	assert.Nil(t, err)
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
 }
 
 func bucketName(t *testing.T) string {