Dellenny presents a practical guide to using GitHub Copilot as an AI-powered assistant for migrating legacy software, focusing on efficient code refactoring and modernization workflows.

How to Migrate Legacy Applications Using GitHub Copilot

Migrating legacy applications to modern platforms is a complex challenge for many development teams. Legacy systems often contain outdated frameworks, unsupported dependencies, and hidden business logic, making refactoring risky and labor-intensive.

The Role of GitHub Copilot

GitHub Copilot acts as an AI pair programmer, helping to:

  • Accelerate repetitive refactoring tasks
  • Suggest modern equivalents for deprecated code
  • Provide scaffolding for newer frameworks and modules

While Copilot cannot fully automate migrations, it significantly reduces manual effort and boosts developer productivity.

Steps for Migration

1. Assess and Plan

  • Inventory your current stack: Identify programming languages, frameworks, and third-party libraries in use.
  • Define your target stack: Example goals include migrating from Python 2 to Python 3, or .NET Framework to .NET 8.
  • Audit dependencies: Flag deprecated libraries that need replacement.
  • Testing strategy: Add unit/integration tests to capture existing behavior.

2. Set Up GitHub Copilot

  • Install Copilot in your IDE (Visual Studio Code, Visual Studio, JetBrains IDEs)
  • Use Copilot Chat for migration-specific queries (e.g., “rewrite this function for Python 3 compatibility”)
  • Configure Copilot for focused suggestions on smaller files/modules

3. Incremental Refactoring with Copilot

  • Syntax upgrades: Copilot can recommend modern syntax (e.g., converting Python 2 print statements to Python 3 print())
  • API updates: Get assistance transitioning from legacy APIs (e.g., older database drivers) to modern equivalents
  • Boilerplate generation: Let Copilot scaffold new services, classes, or test cases

Example: Python 2 to Python 3

def greet(name):
    print "Hello, " + name

With Copilot:

def greet(name: str) -> None:
    print("Hello, " + name)

4. Bridging Old and New Components

  • Use adapters to allow new modules to interface with legacy components
  • Ask Copilot to help draft these adapters

5. Validate with Automated Tests

  • Copilot can aid in authoring unit tests for legacy code
  • Incrementally verify functionality as you modernize modules

6. Continuous Integration and Deployment

  • Set up CI pipelines to automatically run tests with each migration step
  • Deploy updated modules alongside legacy components until the migration is complete

Best Practices for Copilot in Migration Workflows

  • Review Copilot’s code: Always verify suggestions, especially for edge cases
  • Work incrementally: Focus on refactoring one file or module at a time
  • Keep humans in charge: Use Copilot as an assistant, not an automatic decision-maker
  • Leverage Copilot Chat: Ask for clarifications on Copilot’s suggestions

Conclusion

GitHub Copilot streamlines the migration process by reducing repetitive work and helping developers focus on strategic tasks. While it won’t replace human expertise, it acts as a skilled assistant, making legacy application modernization more efficient and less daunting.

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