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scalaprops
What scalaprops is
scalaprops is a free property-based testing library for Scala. It generates test inputs, including non-constant scala.FunctionN functions using Cogen, and lets teams adjust parameters for individual tests. Its law-checking support accepts test identifiers beyond String, and its Scalaz integration includes laws plus Gen and Cogen instances for Scalaz types.
The library uses an immutable random number generator instead of mutable scala.util.Random. On failure, it reports the test's starting seed, which can be passed back with --seed=<value> to repeat the run. Its default generator is Mersenne Twister on JVM and Scala Native, and Tiny Mersenne Twister on Scala.js. The README states support for Scala.js and Scala Native, while Linux is the listed platform. ScalapropsFramework and sbt are the supported test runners.
The project recommends an sbt plugin with a scalapropsOnly command to select a test class, method, and parameter. Timeout support is listed as a feature. The README setup example says parallel test execution is currently unsupported. The repository uses the MIT license, whose terms provide the software without warranty.
Who it suits
scalaprops suits Scala developers who want generated test inputs, repeatable failure runs, or law checking with Scalaz types. It is also a fit for teams using Scala.js or Scala Native alongside the listed Linux platform, provided they can work without parallel test execution.
What it does well
- Generates non-constant scala.FunctionN values through Cogen.
- Supports per-test parameter settings and flexible law checking.
- Reports failure seeds for repeatable runs.
- Includes Scalaz laws and Gen and Cogen instances.
- Offers sbt test selection by class, method, and parameter.
What to know first
- Parallel test execution is currently unsupported.
- The listed platform is Linux, despite stated Scala.js and Scala Native support.
Limits
Parallel test execution is currently unsupported.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Scalaprops | Scala property-based testing library · Maven dependencies shown for test use | Free |
As github.com lists them, read 9 Oct 2026. The maker's own page has the final word.
Getting started
- Open the project website on GitHub.
- Use the Scala library with the listed ScalapropsFramework or sbt test runner.
- Consider the recommended sbt plugin for selecting a test class, method, and parameter.
- Repeat a failing test by supplying its reported seed with --seed=<value>.
Verdict
Choose scalaprops if your Scala tests need generated properties, reproducible failure seeds, or Scalaz law support. Look elsewhere if parallel test execution is required.
Questions
Is scalaprops free?
Yes. It has a free plan, priced at $0, and no free trial.
Which platforms and runtimes does it support?
Linux is the listed platform. The README states support for Scala.js and Scala Native, and lists JVM as a default-generator target.
Can I repeat a failed test?
Yes. Scalaprops emits the starting seed on failure, and you can rerun with --seed=<value>.
Which test runners are supported?
ScalapropsFramework and sbt are listed. The project recommends its sbt plugin for selecting tests.
Is scalaprops open source?
The repository is licensed under MIT.
Facts from scalaprops's own pages
- Deterministic testing
- When a test fails, it emits its starting seed and supports rerunning with --seed=<value>. · github.com, 9 Oct 2026
- Function generators
- It provides generators for scala.FunctionN using Cogen, including non-constant functions. · github.com, 9 Oct 2026
- Law checking
- It supports flexible law checking and can use test identifiers other than String. · github.com, 9 Oct 2026
- License
- The repository is licensed under MIT, whose text provides the software without warranty. · github.com, 9 Oct 2026
- Parallel execution limit
- The README setup example says parallel test execution is currently unsupported. · github.com, 9 Oct 2026
- Purpose
- Scalaprops is a property-based testing library for Scala. · github.com, 9 Oct 2026
- Randomness
- It uses an immutable random number generator and does not use mutable scala.util.Random. · github.com, 9 Oct 2026
- sbt plugin
- The project recommends its sbt plugin, which provides a scalapropsOnly command with test class, method, and parameter selection. · github.com, 9 Oct 2026
- Scalaz integration
- It integrates with Scalaz and provides laws and Gen and Cogen instances for Scalaz types. · github.com, 9 Oct 2026
- Supported runtimes
- The README states support for Scala.js and Scala Native; its default random generator is Mersenne Twister for JVM and Scala Native and Tiny Mersenne Twister for Scala.js. · github.com, 9 Oct 2026
- Test settings
- It supports flexible parameter settings for each test. · github.com, 9 Oct 2026
- Timeouts
- The project lists timeout as soon as possible as a feature. · github.com, 9 Oct 2026
Where scalaprops stands on Freedom251
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