任意のhttp.RoundTripperを利用可能にする

client.go

@@ -55,11 +55,27 @@ type Client struct {
 	config     *Config
 }
 
+// ClientOption is an optional configuration for the client.
+type ClientOption func(*Client)
+
+// WithHTTPRoundTripper sets a Bring-Your-Own http.RoundTripper.
+// By default, http.DefaultTransport is set.
+func WithHTTPRoundTripper(roundTripper http.RoundTripper) ClientOption {
+	return func(c *Client) {
+		c.httpClient.Transport = roundTripper
+	}
+}
+
 // NewClient returns a new freee API client.
-func NewClient(config *Config) *Client {
-	return &Client{
-		config: config,
+func NewClient(config *Config, options ...ClientOption) *Client {
+	client := &Client{
+		httpClient: &http.Client{Transport: http.DefaultTransport},
+		config:     config,
+	}
+	for _, opt := range options {
+		opt(client)
 	}
+	return client
 }
 
 func (c *Client) call(ctx context.Context,
@@ -162,7 +178,7 @@ func (c *Client) do(
 	if c.config.EarlyExpiry != nil {
 		tokenSource = oauth2.ReuseTokenSourceWithExpiry(oauth2Token, tokenSource, *c.config.EarlyExpiry)
 	}
-	httpClient := oauth2.NewClient(ctx, tokenSource)
+	httpClient := oauth2.NewClient(context.WithValue(ctx, oauth2.HTTPClient, c.httpClient), tokenSource)
 	response, err := httpClient.Do(req)
 	if err != nil {
 		e := &oauth2.RetrieveError{}

examples/roundtrip/main.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/LayerXcom/freee-go"
+	"golang.org/x/oauth2"
+)
+
+func main() {
+	clientID := os.Getenv("CLIENT_ID")
+	clientSecret := os.Getenv("CLIENT_SECRET")
+	redirectURL := os.Getenv("REDIRECT_URL")
+	conf := freee.NewConfig(clientID, clientSecret, redirectURL)
+	conf.Log = log.New(os.Stdout, "", log.LstdFlags)
+	client := freee.NewClient(
+		conf, freee.WithHTTPRoundTripper(
+			&http.Transport{
+				Proxy: http.ProxyFromEnvironment,
+				DialContext: (&net.Dialer{
+					Timeout:   30 * time.Second,
+					KeepAlive: 30 * time.Second,
+				}).DialContext,
+				ForceAttemptHTTP2:     true,
+				MaxIdleConns:          100,
+				IdleConnTimeout:       90 * time.Second,
+				TLSHandshakeTimeout:   10 * time.Second,
+				ExpectContinueTimeout: 1 * time.Second,
+			},
+		),
+	)
+
+	ctx := context.Background()
+	token := &oauth2.Token{
+		AccessToken:  os.Getenv("ACCESS_TOKEN"),
+		RefreshToken: os.Getenv("REFRESH_TOKEN"),
+	}
+	me, token, err := client.GetUsersMe(ctx, token, freee.GetUsersMeOpts{})
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("%#v\n", me)
+	fmt.Printf("%#v\n", token)
+}