write tests for UploadTo func errors

Signed-off-by: James Sheppard <jgsheppa@protonmail.com>

pkg/uploader/chart_uploader_test.go

@@ -0,0 +1,30 @@
+package uploader
+
+import (
+	"fmt"
+	"testing"
+
+	"helm.sh/helm/v3/pkg/registry"
+)
+
+func TestUploadTo_InvalidFormatError(t *testing.T) {
+	c := ChartUploader{}
+	remote := "0.google.com:443/abc"
+	got := c.UploadTo("", remote).Error()
+	want := fmt.Errorf("invalid chart URL format: %s", remote).Error()
+
+	if got != want {
+		t.Errorf("expected error to be equal to %v, got %v", want, got)
+	}
+}
+
+func TestUploadTo_SchemaPrefixMissingError(t *testing.T) {
+	c := ChartUploader{}
+	remote := "www.github.com/helm/helm"
+	got := c.UploadTo("", remote).Error()
+	want := fmt.Errorf("scheme prefix missing from remote (e.g. \"%s://\")", registry.OCIScheme).Error()
+
+	if got != want {
+		t.Errorf("expected error to be equal to %v, got %v", want, got)
+	}
+}