add constructor to check url error

examples/okex-book/main.go

@@ -44,10 +44,8 @@ var rootCmd = &cobra.Command{
 			return errors.New("empty key, secret or passphrase")
 		}
 
-		client, err := okexapi.NewClient()
-		if err != nil {
-			return errors.New("init client error: please check url")
-		}
+		client := okexapi.NewClient()
+
 		client.Auth(key, secret, passphrase)
 
 		instruments, err := client.NewGetInstrumentsRequest().

pkg/exchange/okex/exchange.go

@@ -35,10 +35,7 @@ type Exchange struct {
 }
 
 func New(key, secret, passphrase string) (*Exchange, error) {
-	client, err := okexapi.NewClient()
-	if err != nil {
-		return nil, err
-	}
+	client := okexapi.NewClient()
 
 	if len(key) > 0 && len(secret) > 0 {
 		client.Auth(key, secret, passphrase)

pkg/exchange/okex/okexapi/client.go

@@ -66,21 +66,26 @@ type RestClient struct {
 	Key, Secret, Passphrase string
 }
 
-func NewClient() (*RestClient, error) {
-	u, err := url.Parse(RestBaseURL)
+var parsedBaseURL *url.URL
+
+func init() {
+	url, err := url.Parse(RestBaseURL)
 	if err != nil {
-		return nil, err
+		panic(err)
+	}
+	parsedBaseURL = url
 }
 
+func NewClient() *RestClient {
 	client := &RestClient{
 		BaseAPIClient: requestgen.BaseAPIClient{
-			BaseURL: u,
+			BaseURL: parsedBaseURL,
 			HttpClient: &http.Client{
 				Timeout: defaultHTTPTimeout,
 			},
 		},
 	}
-	return client, nil
+	return client
 }
 
 func (c *RestClient) Auth(key, secret, passphrase string) {

pkg/exchange/okex/okexapi/client_test.go

@@ -22,15 +22,13 @@ func getTestClientOrSkip(t *testing.T) *RestClient {
 		return nil
 	}
 
-	client, err := NewClient()
-	assert.NoError(t, err)
+	client := NewClient()
 	client.Auth(key, secret, passphrase)
 	return client
 }
 
 func TestClient_GetInstrumentsRequest(t *testing.T) {
-	client, err := NewClient()
-	assert.NoError(t, err)
+	client := NewClient()
 	ctx := context.Background()
 	req := client.NewGetInstrumentsRequest()
 
@@ -43,8 +41,7 @@ func TestClient_GetInstrumentsRequest(t *testing.T) {
 }
 
 func TestClient_GetFundingRateRequest(t *testing.T) {
-	client, err := NewClient()
-	assert.NoError(t, err)
+	client := NewClient()
 	ctx := context.Background()
 	req := client.NewGetFundingRate()