Matt Keeter describes how an aesthetically pleasing test suite, visualized as colorful 2D and 3D renders, drives development and debugging of his implicit CAD system. He emphasizes the psychological benefit of attractive tests, arguing they encourage more frequent and thorough testing. By visually confirming expected behavior and quickly pinpointing failures through color-coded deviations, the tests guide implementation and accelerate the iterative design process. This approach has proven invaluable in tackling complex geometry problems, allowing him to confidently refactor and extend his system while ensuring correctness.
In a blog post titled "Guided by the beauty of our test suite," author Matt Keeter recounts his experience developing a complex computational geometry library for a procedural modeling tool. He emphasizes the critical role of a comprehensive and aesthetically pleasing test suite in guiding the development process and ensuring the library's robustness and correctness.
Keeter begins by describing the challenges inherent in geometric computations, particularly issues with floating-point precision and edge cases that can lead to unexpected behavior. He argues that traditional debugging methods, such as stepping through code with a debugger, are often insufficient for uncovering these subtle errors. Instead, he advocates for a test-driven development approach centered around building a visually rich test suite.
The author details his process of crafting visualizations for each test case, transforming abstract geometric operations into easily interpretable graphical representations. These visualizations not only serve as a debugging aid by revealing discrepancies between expected and actual results but also act as living documentation of the library's functionality. He highlights the use of color and other visual cues to highlight specific aspects of the geometric operations being tested, making it easier to identify and diagnose problems at a glance.
Keeter further elaborates on the iterative nature of this development process. As he implemented new features or modified existing ones, he simultaneously expanded the test suite with corresponding visualizations. This continuous feedback loop allowed him to quickly identify and address regressions or unexpected side effects. The evolving test suite became a tangible manifestation of the library’s growing capabilities and served as a source of confidence in its stability.
He describes the aesthetic appeal of the resulting test suite, likening it to a gallery of intricate geometric patterns. This visual beauty, he argues, is not merely superficial; it reflects the underlying elegance and correctness of the code itself. The author suggests that striving for visual clarity in the test suite encourages cleaner and more robust code design.
The post concludes by reiterating the importance of investing time and effort in building a well-designed test suite, particularly when dealing with complex domains like computational geometry. Keeter emphasizes that a visually appealing and comprehensive test suite not only improves the development process but also enhances the overall quality and maintainability of the resulting software. He advocates for considering the aesthetics of the test suite as an integral part of software craftsmanship.
Summary of Comments ( 5 )
https://news.ycombinator.com/item?id=42781922
HN commenters largely praised the author's approach to test-driven development and the resulting elegance of the code. Several appreciated the focus on geometric intuition and visualization, finding the interactive, visual tests particularly compelling. Some pointed out the potential benefits of this approach for education, suggesting it could make learning geometry more engaging. A few questioned the scalability and maintainability of such a system for larger projects, while others noted the inherent limitations of relying solely on visual tests. One commenter suggested exploring formal verification methods like TLA+ to complement the visual approach. There was also a brief discussion on the choice of Python and its suitability for such computationally intensive tasks.
The Hacker News post "Guided by the beauty of our test suite" (linking to an article about generative design and testing) sparked a lively discussion with several compelling comments.
One user appreciated the author's approach of using generative testing to uncover edge cases, finding it superior to traditional methods like fuzzing, which they found often produced inputs that were "too random" to be genuinely helpful. They highlighted the elegance of generating tests based on the existing test suite, seeing it as a way to smartly explore the input space.
Another commenter focused on the practical aspects of generative testing, questioning the computational cost. They wondered how long it took to generate and run these tests, and whether the approach was scalable for larger projects. This prompted a response from the original author (Matt Keeter), who clarified that test generation is relatively fast (on the order of seconds), and the bulk of the time is spent running the simulations themselves, which would be necessary regardless of the testing method. He also noted that generating tests close to existing ones could be seen as a form of regression testing, ensuring that new code doesn't break existing functionality in subtle ways.
Another thread discussed the philosophical implications of using aesthetics in engineering. One commenter pondered the connection between beauty and functionality, wondering if a well-designed system is inherently aesthetically pleasing. Another user pushed back, arguing that aesthetics are subjective and can even be misleading. They cautioned against prioritizing beauty over functionality, especially in engineering contexts.
A few commenters shared their own experiences with generative testing and property-based testing, offering alternative approaches and tools. One mentioned using Hypothesis, a popular Python library for property-based testing, while another suggested exploring metamorphic testing, a technique that focuses on relationships between inputs and outputs rather than specific values.
Finally, one user expressed skepticism about the overall premise of the article, arguing that focusing solely on the beauty of the test suite could lead to neglecting the importance of the design itself. They emphasized the need for a holistic approach to design and testing, where both aspects are carefully considered and balanced. This sparked a brief discussion about the role of testing in the design process.
Overall, the comments on the Hacker News post provided a valuable extension of the original article, exploring the practical implications, philosophical underpinnings, and potential pitfalls of generative testing and its relationship to aesthetic design principles.