From 3.x to 4.x
Simple migration guide to fast-check v4 starting from fast-check v3
Changes in minimal requirements
| Name | New requirement | Previous requirement |
|---|---|---|
| TypeScript (optional) | ≥5.0 | ≥4.1 |
Related pull requests: #5577
Update to latest v3.x
Version 4 of fast-check introduces significant changes as part of its major release, including breaking changes. However, many of these changes can be addressed while still using the latest minor release of version 3.
To ensure a smoother migration to version 4, we recommend first upgrading to the latest minor release of version 3. Then, review and address the following deprecation notices to align your codebase with supported patterns.
Changes on date
In version 4, the date arbitrary will generate any Date instances by default, including Invalid Date. If your code cannot handle invalid dates, you should add the noInvalidDate: true constraint to the configuration of your date builder to exclude such values.
-fc.date();
+fc.date({ noInvalidDate: true });
Related pull requests: #5589
Changes on record
In earlier versions, the record arbitrary included a flag named withDeletedKeys. Starting with version 2.11.0, this flag was deprecated and replaced by a new flag called requiredKeys. In version 4.0.0, the deprecated withDeletedKeys flag has been removed entirely.
To migrate, update your usage of the record arbitrary as follows:
fc.record(recordModel, {
- withDeletedKeys: true,
+ requiredKeys: [],
});
fc.record(recordModel, {
- withDeletedKeys: false,
});
Related pull requests: #5578
Advanced usages
Custom reporters
The error field has been removed from the RunDetails object returned by fc.check. If you need access to the error message, use the errorInstance field instead, which was introduced in version 3.0.0.
Related pull requests: #5584
Property execution
If you have implemented a custom class that adheres to the IRawProperty API required by property runners, or if you have created a custom property runner (e.g., a custom implementation of fc.assert or fc.check), this change may affect your code.
The update requires property executors to explicitly call the runBeforeEach and runAfterEach hooks. This adjustment can already be made in version 3 by passing true as the second argument to the run method of properties.
Related pull requests: #5581