fix: handle unexpected http responses

github.go

@@ -53,5 +53,5 @@ func findGitHubREADME(u *url.URL) (*source, error) {
 		}
 	}
 
-	return nil, errors.New("can't find README in GitHub repository")
+	return nil, errors.New(fmt.Sprintf("Can't find README in GitHub repository. Response status: %d %s", res.StatusCode, res.Status))
 }

gitlab.go

@@ -57,5 +57,5 @@ func findGitLabREADME(u *url.URL) (*source, error) {
 		}
 	}
 
-	return nil, errors.New("can't find README in GitLab repository")
+	return nil, errors.New(fmt.Sprintf("Can't find README in GitLab repository. Response status: %d %s", res.StatusCode, res.Status))
 }

glow_test.go

@@ -2,7 +2,8 @@ package main
 
 import (
 	"bytes"
-	"strings"
+	"errors"
+	"net"
 	"testing"
 )
 
@@ -17,16 +18,15 @@ func TestGlowSources(t *testing.T) {
 
 	for _, v := range tt {
 		t.Run(v, func(t *testing.T) {
-			// Start by checking for network issues.
-			_, nerr := readmeURL(v)
-			if nerr != nil && strings.Contains(nerr.Error(), "no such host") {
-				t.Logf("Error during execution (args: %s):\n%v", v, nerr)
-				t.Skip("Test uses network. Are you connected to the Internet?")
-			}
-
 			buf := &bytes.Buffer{}
 			err := executeArg(rootCmd, v, buf)
 			if err != nil {
+				// Check for network issues.
+				var netErr *net.DNSError
+				if errors.As(err, &netErr) {
+					t.Logf("Error during execution (args: %s): %v", v, err)
+					t.Skip("Test uses network. Are you connected to the Internet?")
+				}
 				t.Errorf("Error during execution (args: %s): %v", v, err)
 			}
 			if buf.Len() == 0 {

main.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
@@ -76,6 +77,12 @@ func sourceFromArg(arg string) (*source, error) {
 
 	// a GitHub or GitLab URL (even without the protocol):
 	src, err := readmeURL(arg)
+	// Return error if it's a network issue.
+	var dnsErr *net.DNSError
+	if errors.As(err, &dnsErr) {
+		return src, err
+	}
+
 	if src != nil && err == nil {
 		// if there's an error, try next methods...
 		return src, nil