Use GITHUB_TOKEN if found in environment

main.go

@@ -26,13 +26,19 @@ var (
 	httpTimeout time.Duration
 )
 
+const (
+	tokenKey = "GITHUB_TOKEN"
+)
+
 func main() {
 	exe := path.Base(os.Args[0])
 	flag.BoolVar(&showVersion, "version", false, "show version and exit")
 	flag.DurationVar(&httpTimeout, "timeout", 3*time.Second, "HTTP timeout")
 	flag.Usage = func() {
 		fmt.Fprintf(os.Stderr, "usage: %s [options] [file]\nOptions:\n", exe)
 		flag.PrintDefaults()
+		fmt.Fprintln(os.Stderr)
+		fmt.Fprintf(os.Stderr, "If %s is found in the environment, it will be use to access GitHub API.\n", tokenKey)
 	}
 	flag.Parse()
 
@@ -139,6 +145,11 @@ func repoDesc(owner, repo string) (string, error) {
 		return "", err
 	}
 
+	token := os.Getenv(tokenKey)
+	if token != "" {
+		req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", token))
+	}
+
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return "", err

main_test.go

@@ -3,6 +3,8 @@ package main
 import (
 	"bytes"
 	"context"
+	"fmt"
+	"net/http"
 	"os"
 	"os/exec"
 	"path"
@@ -158,3 +160,32 @@ func TestExeFlags(t *testing.T) {
 		})
 	}
 }
+
+type mockTripper struct {
+	token string
+}
+
+func (t *mockTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	auth := req.Header.Get("Authorization")
+	i := len("Bearer ")
+	if len(auth) > i {
+		t.token = auth[i:]
+	}
+
+	return nil, fmt.Errorf("oopsie")
+}
+
+func TestGHToken(t *testing.T) {
+	token := "s3cr3t"
+	t.Setenv(tokenKey, token)
+
+	oldTransport := http.DefaultClient.Transport
+	var mt mockTripper
+	http.DefaultClient.Transport = &mt
+	t.Cleanup(func() {
+		http.DefaultClient.Transport = oldTransport
+	})
+
+	repoDesc("tebeka", "expmod")
+	require.Equal(t, token, mt.token)
+}