describe at least three technical practices for Continuous Delivery.

Continuous Delivery (CD) is a vital component of agile-based software development methodologies, including Scrum. Essentially, it is a design practice used in software development to establish a system where code changes can be built, tested, and prepared for release reliably and rapidly. This article will delve into three essential technical practices concerning CD, which are mandatory knowledge for individuals preparing for the Advanced Certified Scrum Developer (A-CSD) exam.

1. Version Control Systems (VCS)

A Version Control System is instrumental in managing changes to programs, documents, websites, and other collections of information. In the context of Continuous Delivery, VCS such as Git, Mercurial, and SVN bring numerous advantages. They provide a history of code changes, back up code and changes, allow for experimentation without disrupting the main code, and facilitate collaboration among teams working on a single project.

For instance, Git allows developers to create separate branches to isolate changes for specific features or testing, thereby avoiding code conflicts. Once the update is deemed suitable, it can be merged back into the main code (master branch). This branch-and-merge workflow is a cornerstone feature in Git, empowering teams to experiment and contribute without affecting the live product.

2. Automated Testing

Automated testing is an essential feature of continuous delivery, instrumental in maintaining product quality. It can be categorized into Unit Testing, Integration Testing, and Acceptance Testing.

• Unit Testing: It focuses on the smallest testable unit within a codebase, i.e., individual methods/functions. These tests ensure that each part performs as expected.
• Integration Testing: This checks if the collectively functioning units work as expected when combined. It verifies communication paths and interactions between components to detect interface defects.
• Acceptance Testing: Here, the product’s functionality is checked against the requirements to ensure that the end product is ready for delivery.

For each feature developed, there should be corresponding tests that confirm its functionality. Such tests can be implemented using test frameworks like JUnit, TestNG, or Selenium. These frameworks can be integrated with common CI/CD tools, making automated testing an integrated part of the CD pipelines.

For example, upon each Git commit, a series of automated tests can be executed, notifying any failure or issue to the responsible part. This rapid feedback allows the team to address the problems quickly, fixing them before moving to the next stage in the development cycle.

3. Infrastructure as Code (IaC)

Infrastructure as Code (IaC) is another practice where all infrastructure (networks, servers, databases, etc.) is coded and managed like any other software system. Using languages like Terraform, Chef, Puppet or Ansible, IaC describes and provisions the infrastructure components necessary for an application to run.

With IaC, teams can automatically set up, modify, and tear down environments for testing and production. It enables quick, reliable, and repeatable builds which facilitate continuous delivery. Moreover, any infrastructure changes or updates can be version-controlled, increasing traceability and eliminating manual errors.

For instance, using tools like Terraform, an organization can quickly spin up identical production-like environments for testing or demonstration purposes at any point in the software lifecycle. Similarly, the production environment can be automatically updated to reflect changes in the codebase, thereby enabling a seamless and continuous delivery pipeline.

In summary, Version Control Systems, Automated Testing, and Infrastructure as Code are three critical technical practices in Continuous Delivery. They collectively enable improved code quality, streamlined workflows, and faster delivery times, all of which are vital to Agile and Scrum methodologies. Mastering these practices significantly enhances an individual’s productivity as a Certified Scrum Developer and their broader understanding of effective software delivery.