add retry package

internal/retry/error_test.go

@@ -0,0 +1,29 @@
+package retry_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/pomerium/pomerium/internal/retry"
+)
+
+type testError string
+
+func (e testError) Error() string {
+	return string(e)
+}
+
+func (e testError) IsTerminal() {}
+
+func TestError(t *testing.T) {
+	t.Run("local terminal error", func(t *testing.T) {
+		err := fmt.Errorf("wrap: %w", retry.NewTerminalError(fmt.Errorf("inner")))
+		require.True(t, retry.IsTerminalError(err))
+	})
+	t.Run("external terminal error", func(t *testing.T) {
+		err := fmt.Errorf("wrap: %w", testError("inner"))
+		require.True(t, retry.IsTerminalError(err))
+	})
+}