diff --git a/internal/proxy/client.go b/internal/proxy/client.go
index bcbe3b9..7c07b88 100644
--- a/internal/proxy/client.go
+++ b/internal/proxy/client.go
@@ -404,7 +404,7 @@ func (c *Client) sendKeepAlive(ctx context.Context, stream cloudproxyv1alpha.Clo
 						return fmt.Errorf("stream ended with %w", stream.Context().Err())
 					}
 					if err := c.isAlive(); err != nil {
-						return err
+						return fmt.Errorf("isAlive: %w", err)
 					}
 				}
 			}
diff --git a/internal/proxy/client_test.go b/internal/proxy/client_test.go
index f9dec3e..30a5b01 100644
--- a/internal/proxy/client_test.go
+++ b/internal/proxy/client_test.go
@@ -491,3 +491,99 @@ func TestClient_Run(t *testing.T) {
 		})
 	}
 }
+
+func TestClient_sendKeepAlive(t *testing.T) {
+	t.Parallel()
+
+	type args struct {
+		ctx              func() context.Context
+		tuneMockStream   func(m *mock_proxy.MockCloudProxyAPI_StreamCloudProxyClient)
+		lastSeenSend     int64
+		lastSeenReceive  int64
+		keepAlive        int64
+		keepAliveTimeout int64
+		sendCh           chan *cloudproxyv1alpha.StreamCloudProxyRequest
+	}
+	tests := []struct {
+		name       string
+		args       args
+		wantErrMsg string
+	}{
+		{
+			name: "context done",
+			args: args{
+				ctx: func() context.Context {
+					ctx, cancel := context.WithCancel(context.Background())
+					cancel()
+					return ctx
+				},
+				tuneMockStream: func(m *mock_proxy.MockCloudProxyAPI_StreamCloudProxyClient) { // expected 0 or 1 times.
+					m.EXPECT().Context().Return(context.Background()).AnyTimes() // expected 0 or 1 times.
+				},
+				lastSeenSend:     time.Now().UnixNano(),
+				lastSeenReceive:  time.Now().UnixNano(),
+				keepAlive:        int64(time.Hour),
+				keepAliveTimeout: int64(time.Hour),
+				sendCh:           make(chan *cloudproxyv1alpha.StreamCloudProxyRequest, 100),
+			},
+			wantErrMsg: "context ended with context canceled",
+		},
+		{
+			name: "skip keep alive",
+			args: args{
+				ctx: func() context.Context {
+					ctx, _ := context.WithTimeout(context.Background(), time.Second)
+					return ctx
+				},
+				lastSeenReceive:  time.Now().Add(time.Minute).UnixNano(),
+				lastSeenSend:     time.Now().Add(time.Minute).UnixNano(),
+				keepAlive:        int64(time.Millisecond),
+				keepAliveTimeout: int64(time.Hour),
+				sendCh:           make(chan *cloudproxyv1alpha.StreamCloudProxyRequest),
+			},
+			wantErrMsg: "context ended with context deadline exceeded",
+		},
+		{
+			name: "sendch is full and exit with not alive",
+			args: args{
+				ctx: func() context.Context {
+					ctx, _ := context.WithTimeout(context.Background(), time.Second*2)
+					return ctx
+				},
+				lastSeenReceive:  time.Now().Add(-time.Minute).UnixNano(),
+				lastSeenSend:     time.Now().Add(-time.Minute).UnixNano(),
+				keepAlive:        int64(time.Millisecond),
+				keepAliveTimeout: int64(time.Second * 2),
+				sendCh:           make(chan *cloudproxyv1alpha.StreamCloudProxyRequest, 1),
+				tuneMockStream: func(m *mock_proxy.MockCloudProxyAPI_StreamCloudProxyClient) {
+					m.EXPECT().Context().Return(context.Background()).AnyTimes()
+				},
+			},
+			wantErrMsg: "isAlive: client connection is not alive",
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			c := &Client{
+				log: logrus.New(),
+			}
+			c.keepAlive.Store(tt.args.keepAlive)
+			c.keepAliveTimeout.Store(tt.args.keepAliveTimeout)
+			c.lastSeenSend.Store(tt.args.lastSeenSend)
+			c.lastSeenReceive.Store(tt.args.lastSeenReceive)
+			ctrl := gomock.NewController(t)
+			defer ctrl.Finish()
+			stream := mock_proxy.NewMockCloudProxyAPI_StreamCloudProxyClient(ctrl)
+			if tt.args.tuneMockStream != nil {
+				tt.args.tuneMockStream(stream)
+			}
+			err := c.sendKeepAlive(tt.args.ctx(), stream)
+			require.Equal(t, len(tt.wantErrMsg) > 0, err != nil, "error: %v", err)
+			if err != nil {
+				require.Equal(t, tt.wantErrMsg, err.Error(), "error: %v", err)
+			}
+		})
+	}
+}