chore: add files cache for reading template tar archives from db (#17141)

coderd/util/lazy/valuewitherror_test.go

@@ -0,0 +1,52 @@
+package lazy_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"golang.org/x/xerrors"
+
+	"github.com/coder/coder/v2/coderd/util/lazy"
+)
+
+func TestLazyWithErrorOK(t *testing.T) {
+	t.Parallel()
+
+	l := lazy.NewWithError(func() (int, error) {
+		return 1, nil
+	})
+
+	i, err := l.Load()
+	require.NoError(t, err)
+	require.Equal(t, 1, i)
+}
+
+func TestLazyWithErrorErr(t *testing.T) {
+	t.Parallel()
+
+	l := lazy.NewWithError(func() (int, error) {
+		return 0, xerrors.New("oh no! everything that could went horribly wrong!")
+	})
+
+	i, err := l.Load()
+	require.Error(t, err)
+	require.Equal(t, 0, i)
+}
+
+func TestLazyWithErrorPointers(t *testing.T) {
+	t.Parallel()
+
+	a := 1
+	l := lazy.NewWithError(func() (*int, error) {
+		return &a, nil
+	})
+
+	b, err := l.Load()
+	require.NoError(t, err)
+	c, err := l.Load()
+	require.NoError(t, err)
+
+	*b++
+	*c++
+	require.Equal(t, 3, a)
+}