feat: add test file for reading AsGrouped via dask or virtual array (#225)

Author: mrzimu

dev/make-root/uproot_issue_1502.C

@@ -0,0 +1,31 @@
+#include <TFile.h>
+#include <TObject.h>
+#include <TTree.h>
+
+class TMyObject : public TObject {
+  private:
+    int value;
+
+  public:
+    TMyObject( int i ) : value( i ) {}
+
+    ClassDef( TMyObject, 1 );
+};
+
+void uproot_issue_1502() {
+    TFile f( "uproot-issue-1502.root", "RECREATE" );
+    TTree tree( "tree", "tree" );
+
+    TMyObject obj{ 0 };
+
+    tree.Branch( "branch", &obj );
+
+    for ( int i = 0; i < 10; i++ )
+    {
+        obj = TMyObject( i );
+        tree.Fill();
+    }
+
+    tree.Write();
+    f.Close();
+}