0.4.3

[nth-commit]

Rendering improvements

This release greatly improves how counterexamples are printed when a property is falsified, as well as how samples are printed when using [Sample]. Previously, GalaxyCheck would render examples using System.Text.Json.JsonSerializer. This constrained rendering in to the JSON format, which is more verbose and strict than it needs to be for this purpose.

This constrained us in several ways. For example (but not limited to):

• Property names always need to be quoted, which adds unnecessary noise for a human reader
• Property values had to be JSON values, so when you had a dictionary where the key was not a string/number, we wrote in a JSON comment to denote the key, which was messy and hard to understand.
• Properties that threw on access crashed the rendered. Now we write in a "rendering failed" token when rendering any part of the object fails. Previously, if any part of the object failed to serialize, the JSON exception would bubble up and destroy any information about the original property failure (including how to reproduce it!).
• Circular references crashed the renderer. Now we have a custom handler which writes in a "circular reference" token when one is detected.

Other improvements are outlined in the tests.

This also removes the external dependency on System.Text.Json, which is not included in netstandard2.0.

Falsified stack traces are now of the user's code

An intrinsic part of GalaxyCheck (and most other property-based testing frameworks) is about finding the smallest counterexample to a property. A property will normally be run many times after it initially fails, as the input to each test case gets smaller.

This means that exceptions can't be directly bubbled back to the user. GalaxyCheck needs to intercept exceptions, hold onto them, then eventually return the exception that was associated with the smallest counterexample. Naturally, this is destructive to stack traces - and meant that in earlier versions of GalaxyCheck, when viewing the test output for a falsified property, you would see a stack trace for code inside GalaxyCheck itself.

This release improves upon that by augmenting GalaxyCheck's PropertyFailedException, with the stack trace of the exception from the user's code (if there was one).

Shrink limit is always respected

When specifying a property, you can configure the shrink limit, e.g. [Property(ShrinkLimit = 10)]. This is a good way to put a hard limit on the amount of time GalaxyCheck can spend finding the smallest counterexample, and by default it's set at 500.

However, GalaxyCheck didn't always respect that limit, which meant for things that are hard to shrink, GalaxyCheck could spend an inappropriate amount of time spinning on. This release fixes that.

More run parameters exposed through PropertyAttribute

PropertyAttribute adds Seed and Size, which allows you to tightly control generation upfront. Useful for debugging.

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This discussion was created from the release 0.4.3.