Test automation is a key component in Agile development, particularly in the context of continuous deployment and delivery. The level of test automation can indeed influence and potentially constrain the frequency of code deployments. This is because the extent and robustness of automated tests determine how quickly and reliably new code can be pushed to production. If the test automation is not comprehensive or reliable, it may require additional manual testing or cause delays in deployment. Conversely, a high level of test automation can support more frequent and confident deployments by ensuring that new changes do not break existing functionality.

References = The ISTQB Advanced Level Agile Technical Tester syllabus discusses the importance of test automation in Agile projects, including its impact on continuous deployment and delivery12.