Fixing FakeDriver: Screen Change & Resize Testing Architecture

Hey guys! Let's dive into the exciting world of terminal UI testing and how we're tackling some key challenges with FakeDriver in our architecture. This article is all about the follow-up on our FakeDriver testing architecture, specifically focusing on ScreenChanged and FakeResize. We'll walk through the steps, the fixes, and the remaining work to be done. So, buckle up and let's get started!

Initial Steps and Setup

First things first, we need to create a new pull request (PR). To ensure we're on the same page, the PR should start from commit 8d9633274e3e2c05b91b19cdacdf03d2ac32c391. This commit serves as our baseline, the solid foundation upon which we'll build our improvements. This is crucial because it allows us to isolate our changes and track them effectively.

Why this commit, you ask? Well, this particular commit represents a stable point in our development history. It’s like a snapshot of the project at a specific moment, free from the bugs or issues we're trying to address. Starting from here ensures that any problems we encounter are directly related to our changes, rather than pre-existing issues. It's a clean slate, ready for our innovative work.

Once we've established our starting point, the next step involves a little bit of detective work. We need to study the Git history from this commit up to the point where the PR was created from v2_develop. This means digging into the commit logs, examining the changes made, and understanding the evolution of the codebase. It's like reading the story of the project's development, chapter by chapter.

This deep dive into the Git history isn't just for fun; it’s essential for context. By understanding what changes have been made, why they were made, and how they interact, we gain invaluable insights. We can identify potential conflicts, understand the rationale behind certain decisions, and anticipate any unforeseen consequences. It’s about getting the big picture before we start making our own contributions.

Next up, we need to study the description and comments in issue #4347. This is where the real meat of the problem lies. The issue description often contains a high-level overview of the problem, the goals of the fix, and any constraints or considerations. It's the executive summary of our mission.

But the comments are where the magic really happens. They provide a detailed discussion of the issue, with insights from various contributors, proposed solutions, and feedback on those solutions. It’s like a virtual brainstorming session, where developers collaborate to dissect the problem and come up with the best approach. This is invaluable for understanding the nuances of the problem and avoiding potential pitfalls. Understanding the discussions and decisions made in #4347 ensures that our efforts are aligned with the project's goals and that we're not reinventing the wheel.

Addressing Test Failures

Now, let's talk about the fun part – running tests and squashing bugs! Once the PR is created, the next crucial step is to run all the unit tests, specifically both UnitTests and UnitTests.Parallizable. These tests are our first line of defense, designed to catch any regressions or issues introduced by our changes. Think of them as a safety net, ensuring that our code behaves as expected.

Running both sets of tests is essential because they cover different aspects of the codebase. UnitTests provides a broad range of tests, covering various functionalities and scenarios. UnitTests.Parallizable, on the other hand, focuses on tests that can be run in parallel, helping to identify concurrency issues and performance bottlenecks. By running both, we ensure a comprehensive evaluation of our changes.

Inevitably, you'll see failures. Don't panic! This is a normal part of the development process. Test failures are not a sign of failure; they're a sign that the tests are doing their job. They're highlighting potential problems that need our attention.

The real challenge, and the real learning opportunity, comes in diving into each failure and fixing the problem. This involves a systematic approach: examining the test output, understanding the error message, tracing the code execution, and identifying the root cause of the failure. It’s like being a detective, piecing together clues to solve a mystery.

Each test failure tells a story. It might be a simple typo, a logic error, a missed edge case, or a misunderstanding of how different parts of the system interact. By carefully analyzing the failure, we gain a deeper understanding of the codebase and the impact of our changes. This process not only fixes the immediate problem but also helps us become better developers.

Fixing the problem often involves a combination of debugging, code modification, and re-testing. We might need to step through the code line by line, using a debugger to inspect variables and track the program's flow. We might need to adjust our code to handle different scenarios or edge cases. And, of course, we need to re-run the tests to ensure that our fix has actually resolved the issue and hasn't introduced any new problems.

This iterative process of testing, debugging, and fixing is at the heart of software development. It's a continuous cycle of learning, improvement, and refinement. Each failure is an opportunity to grow, to understand the system better, and to write more robust and reliable code.

Remaining Tasks After Fixing Tests

Once we've successfully navigated the treacherous waters of test failures and emerged victorious, there's still some work to be done. Think of it as the final polish, the finishing touches that elevate our work from good to great. Here are the key tasks that remain:

Rename SizeChanged to ScreenChanged (+ Obsolete Shim)

First up, we need to tackle a naming convention. The term SizeChanged is a bit ambiguous. It doesn't clearly convey what's actually changing – the screen. To improve clarity and maintainability, we'll rename SizeChanged to ScreenChanged. This makes it immediately obvious what event we're dealing with: a change in the screen.

But, as with any renaming operation, we need to be careful. Simply renaming the event would break any existing code that uses the old name. To avoid this, we'll introduce an obsolete shim. This means we'll keep the old SizeChanged event around, but mark it as obsolete. When someone tries to use it, the compiler will issue a warning, guiding them to the new ScreenChanged event.

This approach provides a smooth transition. Existing code continues to work, but developers are gently nudged towards the new, more descriptive name. It's a balance between maintaining compatibility and improving the codebase.

Refactor AutoInitShutdownAttribute.FakeResize to Use SetScreenSize

Next, we'll be diving into the AutoInitShutdownAttribute.FakeResize functionality. Currently, it might be using a less-than-ideal method for resizing the screen. We want to refactor this to use SetScreenSize. Why? Because SetScreenSize is the standard, recommended way to change the screen size. It encapsulates the logic for updating the screen dimensions and ensuring that everything is properly synchronized.

This refactoring is about consistency and maintainability. By using SetScreenSize, we ensure that all screen resizing operations go through the same path, reducing the risk of inconsistencies and making the code easier to understand and maintain. It's about building a solid foundation for future development.

Add Tests: ScreenChanged Firing, Buffer Integrity, FakeResize Behavior

Ah, tests! We can never have too many tests, especially when dealing with critical functionality like screen resizing. We need to add tests to cover three key areas:

• ScreenChanged Firing: We need to ensure that the ScreenChanged event is fired correctly when the screen size changes. This is the core of the functionality, and we need to verify that it works as expected in various scenarios.
• Buffer Integrity: When the screen size changes, the underlying buffer that stores the screen contents also needs to be updated. We need to add tests to ensure that this buffer remains consistent and that no data is lost or corrupted during resizing. This is crucial for maintaining the integrity of the user interface.
• FakeResize Behavior: We need to thoroughly test the behavior of FakeResize. This includes verifying that it correctly sets the screen size, that it triggers the ScreenChanged event, and that it interacts correctly with other parts of the system. A comprehensive set of tests will give us confidence that FakeResize is robust and reliable.

Normalize SetScreenSize NotImplemented Exception Message

Exception messages are often overlooked, but they're crucial for debugging. When SetScreenSize is not implemented, it should throw an exception with a clear and informative message. We need to normalize this message, ensuring that it's consistent across different platforms and implementations. A standardized message makes it easier to diagnose problems and reduces confusion.

Update XML Docs

Last but not least, we need to update the XML documentation. Documentation is the key to making our code accessible and understandable to others (and to our future selves!). We need to ensure that the documentation accurately reflects the changes we've made, including the renaming of SizeChanged to ScreenChanged, the refactoring of FakeResize, and any new functionality we've added. Up-to-date documentation is a gift to the development community.

Fixes #4346

And, of course, this whole endeavor is aimed at fixing issue #4346. This line ties our work back to the original problem, providing context and ensuring that our efforts are focused and aligned with the project's goals.

Conclusion

So there you have it, guys! A comprehensive overview of the follow-up work on our FakeDriver testing architecture. From creating the PR to fixing test failures and polishing the final details, it's a journey of learning, problem-solving, and collaboration. By tackling these challenges head-on, we're not only improving the quality of our code but also building a stronger, more robust terminal UI testing framework. Keep up the great work!