afterEach and beforeEach for property tests

I’m trying to make a property based test based on actually manipulating the dom and then comparing two different dom states.

I’m using the mocha test runner. However, I’m having a problem with the state getting out of sync because the afterEach and beforeEach triggers for mocha do not trigger pre and post fast-check test as they’re separate systems. So naturally I’ve moved most of the setup and tear down code into the property test predicate. This gets pretty cluttered.

What do you think about adding hooks in the assert parameters for running setup/teardown? Something like the following.

export interface Parameters<T = void> {
    seed?: number;      // optional, initial seed of the generator: Date.now() by default
    numRuns?: number;   // optional, number of runs before success: 100 by default
    maxSkipsPerRun?: number; // optional, maximal number of skipped entries per run: 100 by default
    timeout?: number;   // optional, only taken into account for asynchronous runs (asyncProperty)
                        // specify a timeout in milliseconds, maximum time for the predicate to return its result
                        // only works for async code, will not interrupt a synchronous code: disabled by default
    path?: string;      // optional, way to replay a failing property directly with the counterexample
                        // it can be fed with the counterexamplePath returned by the failing test (requires seed too)
    logger?: (v: string) => void; // optional, log output: console.log by default
    unbiased?: boolean; // optional, force the use of unbiased arbitraries: biased by default
    verbose?: boolean;  // optional, enable verbose mode: false by default
                        // when enabling verbose mode,
                        // you will be provided the list of all failing entries encountered
                        // whenever a property fails - useful to detect patterns
    examples?: T[];     // optional, custom values added to generated ones: [] by default
                        // when set, those examples will be run against the property first
                        // followed by the values generated by the framework
                        // they do not increase the number of times the property will be launched
    afterEach?: () => void; //runs teardown code after each property test
    beforeEach?: () => void; //runs setup code before each property test begins
}

Or maybe add them to the property

interface IProperty<Ts> {
    ...
    afterEach?: () => void; //runs teardown code after each property test
    beforeEach?: () => void; //runs setup code before each property test begins
}

It isn’t a super important issue, but it might be a small quality of life feature.

[MehdiSaffar]

@dubzzz I wasn’t aware of the beforeEach and afterEach hooks of fast-check. Thanks a lot.

[dubzzz]

You can use: fc.configureGlobal({beforeEach, afterEach}). But otherwise so far, there is no such capability in @fast-check/jest. You should definitely open an issue so that it can be tracked