A still from my first Developer's meetup

Yesterday was one of those moments where I found myself in a room full of developers and was probably the only tester there.

I was speaking about Property-Based Testing with Hypothesis at the SciPy India × Rust Delhi meetup, and one example stayed with me. We tested the simple assumption that an average should always lie between the two numbers.

Hypothesis pushed the inputs to around 8e307 to 9e307, where floating-point addition can overflow. The sum becomes infinity, and suddenly our perfectly valid property fails.

The math was right. We had just reached the limit of the machine.

A nice reminder that sometimes the most interesting bugs hide behind things we assume are obvious.