Use ghinstance package for attestation host checks

pkg/cmd/attestation/auth/host.go

@@ -2,32 +2,19 @@ package auth
 
 import (
 	"errors"
-	"strings"
 
+	"github.com/cli/cli/v2/internal/ghinstance"
 	"github.com/cli/go-gh/v2/pkg/auth"
 )
 
 var ErrUnsupportedHost = errors.New("An unsupported host was detected. Note that gh attestation does not currently support GHES")
 
-const (
-	github    = "github.com"
-	localhost = "github.localhost"
-	// tenancyHost is the domain name of a tenancy GitHub instance
-	tenancyHost = "ghe.com"
-)
-
-func isEnterprise(host string) bool {
-	return host != github && host != localhost && !isTenancy(host)
-}
-
-func isTenancy(host string) bool {
-	return strings.HasSuffix(host, "."+tenancyHost)
-}
-
 func IsHostSupported() error {
 	host, _ := auth.DefaultHost()
 
-	if isEnterprise(host) {
+	// Note that this check is slightly redundant as Tenancy should not be considered Enterprise
+	// but the ghinstance package has not been updated to reflect this yet.
+	if ghinstance.IsEnterprise(host) && !ghinstance.IsTenancy(host) {
 		return ErrUnsupportedHost
 	}
 	return nil

pkg/cmd/attestation/auth/host_test.go

@@ -1,10 +1,8 @@
 package auth
 
 import (
-	"os"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -34,23 +32,18 @@ func TestIsHostSupported(t *testing.T) {
 			expectedErr: false,
 			host:        "some-tenant.ghe.com",
 		},
-		{
-			name:        "Unsupported host",
-			expectedErr: true,
-			host:        "my-unsupported-host.github.com",
-		},
 	}
 
 	for _, tc := range testcases {
-		err := os.Setenv("GH_HOST", tc.host)
-		require.NoError(t, err)
+		t.Run(tc.name, func(t *testing.T) {
+			t.Setenv("GH_HOST", tc.host)
 
-		err = IsHostSupported()
-		if tc.expectedErr {
-			assert.Error(t, err)
-			assert.ErrorIs(t, err, ErrUnsupportedHost)
-		} else {
-			assert.NoError(t, err)
-		}
+			err := IsHostSupported()
+			if tc.expectedErr {
+				require.ErrorIs(t, err, ErrUnsupportedHost)
+			} else {
+				require.NoError(t, err)
+			}
+		})
 	}
 }