jsverify
fast-check
jsverify | fast-check | |
---|---|---|
5 | 21 | |
1,666 | 4,107 | |
0.1% | - | |
1.8 | 9.8 | |
about 3 years ago | 2 days ago | |
JavaScript | TypeScript | |
MIT License | MIT License |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
jsverify
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The 5 principles of Unit Testing
Libraries like JSVerify or Fast-Check offer essential tools to facilitate property-based testing.
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Ask HN: What's your favorite software testing framework and why?
I tend to use anything that offers property-testing, since tests are much shorter to write and uncover lots more hidden assumptions.
My go-to choices per language are:
- Python: Hypothesis https://hypothesis.readthedocs.io/en/latest (also compatible with PyTest)
- Scala: ScalaCheck https://scalacheck.org (also compatible with ScalaTest)
- Javascript/Typescript: JSVerify https://jsverify.github.io
- Haskell: LazySmallCheck2012 https://github.com/UoYCS-plasma/LazySmallCheck2012/blob/mast...
- When I wrote PHP (over a decade ago) there was no decent property-based test framework, so I cobbled one together https://github.com/Warbo/php-easycheck
All of the above use the same basic setup: tests can make universally-quantified statements (e.g. "for all (x: Int), foo(x) == foo(foo(x))"), then the framework checks that statement for a bunch of different inputs.
Most property-checking frameworks generate data randomly (with more or less sophistication). The Haskell ecosystem is more interesting:
- QuickCheck was one of the first property-testing frameworks, using random genrators.
- SmallCheck came later, which enumerates data instead (e.g. testing a Float might use 0, 1, -1, 2, -2, 0.5, -0.5, etc.). That's cute, but QuickCheck tends to exercise more code paths with each input.
- LazySmallCheck builds up test data on-demand, using Haskell's pervasive laziness. Tests are run with an error as input: if they pass, we're done; if they fail, we're done; if they trigger the error, they're run again with slightly more-defined inputs. For example, if the input is supposed to be a list, we try again with the two forms of list: empty and "cons" (the arguments to cons are both errors, to begin with). This exercises even more code paths for each input.
- LazySmallCheck2012 is a more versatile "update" to LazySmallCheck; in particular, it's able to generate functions.
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Property Based Testing Framework for Node
The usage of hypothesis is very intuitive and simple, and presents the concept of property-based testing perfectly. So I also wanted to find an equivalent alternative in Node. Two of them have high star ratings on Github, JSVerify with 1.6K stars and fast-check with 2.8K stars. So I took some time to study fast-check a little bit and try to get closer to my daily work.
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Machine Readable Specifications at Scale
Systems I've used for this include https://agda.readthedocs.io/en/v2.6.0.1/getting-started/what... https://coq.inria.fr https://www.idris-lang.org and https://isabelle.in.tum.de
An easier alternative is to try disproving the statement, by executing it on thousands of examples and seeing if any fail. That gives us less confidence than a full proof, but can still be better than traditional "there exists" tests. This is called property checking or property-based testing. Systems I've used for this include https://hypothesis.works https://hackage.haskell.org/package/QuickCheck https://scalacheck.org and https://jsverify.github.io
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React to Elm Migration Guide
Using create-react-app, you’ll run npm test which uses Jest internally. If you are dealing with a lot of data on the UI, or using TypeScript, use JSVerify for property tests. For end to end tests, Cypress is a great choice.
fast-check
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The 5 principles of Unit Testing
Libraries like JSVerify or Fast-Check offer essential tools to facilitate property-based testing.
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How to Survive Your Project's First 100k Lines
Strong agree!
For JavaScript, I suggest folks check out fast-check [0] and this introduction to property-based testing that uses fast-check [1].
This is broadly useful, but one specific place I've found it helpful was to check redux reducers against generated lists of actions to find unchecked edge cases and data assumptions.
[0] https://github.com/dubzzz/fast-check
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Master property-based testing in JavaScript: A step-by-step tutorial
Brilliant, this is a massive improvement. Previously I was fumbling around in https://github.com/dubzzz/fast-check/tree/main/packages/fast-check/documentation for info.
- Bring the power of property based testing framework fast-check into Vitest
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[AskJS] Should I be generating random data for parameters when unit testing?
There's a library for exactly that: FastCheck.
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Integrate Jest and fast-check together
It makes @fast-check/jest, the best option to integrate Jest and fast-check, as it provides an abstraction over both to ease their mutual integration.
- I Created an API to Generate Mock Information
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Generating dummy entities with random data for tests based on types
The closest that I know of (and I have not used this) is zod-fast-check. It generates fast-check “arbitraries” (test data generators) for property-based testing based on zod schemas. Of course, this requires that you use zod to define your types, which has some downsides. Fortunately there is another tool, ts-to-zod, (which I also have not used) which will codegen zod schemas based on TS type definitions. If you thread these four libraries together you should end up with the ability to write random tests on generated data with very little overhead. In theory.
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Best practice where to test validation?
For something like this, I might break out fast-check for testing. It’s good at generating a wide range of values for a given type, and could help you get good test coverage without having to hand-author a lot of repetitive error inputs.
- Fast-check: How it works
What are some alternatives?
greenlight - Clojure integration testing framework
Unexpected - Unexpected - the extensible BDD assertion toolkit
testy - test helpers for more meaningful, readable, and fluent tests
jest - Delightful JavaScript Testing.
LazySmallCheck2012 - Lazy SmallCheck with functional values and existentials!
tape - tap-producing test harness for node and browsers
hitchstory - Type-safe YAML integration tests. Tests that write your docs. Tests that rewrite themselves.
trevor - 🚦 Your own mini Travis CI to run tests locally
datadriven - Data-Driven Testing for Go
test-each - 🤖 Repeat tests. Repeat tests. Repeat tests.
php-easycheck - Mirror of http://chriswarbo.net/git/php-easycheck
nyc - the Istanbul command line interface