Abstract. Background: Containers are a commonly used solution for deploying software applications. Therefore, container functionality and security is a concern of practitioners and researchers. Testing is an essential aspect to ensure the quality of the container environment component and the software product, and plays a crucial role in using containers.

Objective: In light of the increasing role of software containers and the lack of research on testing them, we study container testing practices. In this paper, we investigate the current approaches for testing containers. Moreover, we aim to identify areas for improvement and emphasize the importance of testing in securing the container environment and the final software product.

Method: We conducted a survey to collect primary data from companies implementing container testing practices and the commonly used tools in container testing. There were 14 respondents from a total of ten different companies with experience using containers and varying work responsibilities.

Findings: The survey findings illustrate the significance of testing, the growing interest in and utilization of containers, and the emerging security and vulnerability concerns. The research reveals variations in testing approaches between companies and the lack of consensus on how testing should be carried out, with advancements primarily driven by industry practices rather than academic research.

Conclusion: In this study we show the importance of testing software containers. It lays out the current testing approaches, challenges, and the need for standardized container testing practices. We also provide recommendations on how to develop these practices further.