As Generative Artificial Intelligence (GenAI) is becoming ubiquitous across learning domains, it is crucial to better understand how learning experiences could take advantage of its possibilities and avoid its pitfalls. In this paper, we address this issue by focusing on the context of a data visualization course. What makes this context unique is its combination of two areas where GenAI has shown notable effectiveness: writing code and storytelling. To evaluate how undergraduate students would leverage GenAI in this context, we conducted an in-class between-subjects experiment (N = 43) with a control (no GenAI) and treatment group (with GenAI). In the 60-min experiment, students from the data visualization course were asked to prepare a data story within Jupyter Notebook, including both textual story elements and data visualization. In addition to these two groups, we included AI-only group in which task instructions were given directly to a GenAI tool without further human intervention. The results of our experiment indicate that students perceive GenAI as a tool improving both their learning experience and outcomes. However, an analysis of the learning outcomes exhibits no statistically significant difference between creations of students with or without GenAI support. Interestingly, the outputs generated by GenAI alone outperformed those of both student groups.