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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 | 1x 1x 1x 1x 1x 3039x 3039x 3039x 3039x 3039x 3039x 3039x 3039x 3039x 3035x 3035x 1x 1x 2091x 2091x 2091x 2091x 3037x 3037x 3037x 3037x 3037x 3037x 3037x 3037x 3037x 1x 1x 1x 1x 1x 1x 400x 400x 400x 1x 90x 90x 90x | /**
* Predicates for statistical testing of equality between functions.
* @module
*/
import {Boolean as BO, Equivalence as EQ, Option as OP, pipe} from 'effect'
import {constFalse, constTrue} from 'effect/Function'
import fc from 'fast-check'
/**
* Attempt to find an example input where the pair of given unary functions
* is not equal. Given an arbitrary of `A`, an equivalence for `B` and a
* pair of functions, check the functions compute the same `B` given the
* same `A`, for `numRuns` values. Returns none or some value found.
* @param a - An arbitrary for the function argument type `A`.
* @param equalsB - Equivalence for the function return value type `B`.
* @param parameters - Optional [fast-check parameters](https://fast-check.dev/api-reference/interfaces/Parameters.html).
* @returns `none` if no counterexample to the equivalence was found, else
* `some` of the `A` that was found to produce different values.
* @category equivalence
*/
export const findCounterexample =
<A, B>(
a: fc.Arbitrary<A>,
equalsB: EQ.Equivalence<B>,
parameters?: fc.Parameters<A>,
) =>
(
/**
* First function to sample.
*/
self: (a: A) => B,
/**
* Second function to sample.
*/
that: typeof self,
): OP.Option<A> => {
const samples: A[] = fc.sample(a, parameters)
/* v8 ignore next 1 */
if (samples.length === 0) throw new Error('Empty sample.')
for (const a of samples) if (!equalsB(self(a), that(a))) return OP.some(a)
return OP.none()
}
/**
* Attempt to find an example input where the pair of given unary functions
* is not equal. Given an arbitrary of `A`, an equivalence for `B` and a
* pair of functions, check the functions compute the same `B` given the
* same `A`, for `numRuns` values. Returns a boolean flag indicating
* equivalence.
* @param a - An arbitrary for the function argument type `A`.
* @param equalsB - Equivalence for the function return value type `B`.
* @param parameters - Optional [fast-check parameters](https://fast-check.dev/api-reference/interfaces/Parameters.html).
* @returns True if no counterexample found, else false.
* @category equivalence
*/
export const testUnaryEquivalence =
<A, B>(
a: fc.Arbitrary<A>,
equalsB: EQ.Equivalence<B>,
parameters?: fc.Parameters<A>,
) =>
(
/**
* First function to sample.
*/
self: (a: A) => B,
/**
* Second function to sample.
*/
that: typeof self,
): boolean =>
pipe(
findCounterexample(a, equalsB, parameters)(self, that),
OP.match({
onNone: constTrue,
onSome: constFalse,
}),
)
/**
* Same as `testUnaryEquivalence` but for functions of type `Endo<A>`.
* @param a - An arbitrary for the function argument type `A`.
* @param equalsA - Equivalence for the type `A`.
* @param parameters - Optional [fast-check parameters](https://fast-check.dev/api-reference/interfaces/Parameters.html).
* @returns True if no counterexample found, else false.
* @category equivalence
*/
export const testEndoEquivalence =
<A>(
a: fc.Arbitrary<A>,
equalsA: EQ.Equivalence<A>,
parameters?: fc.Parameters<A>,
) =>
(
/**
* First function to sample.
*/
self: (a: A) => A,
/**
* Second function to sample.
*/
that: typeof self,
): boolean =>
testUnaryEquivalence(a, equalsA, parameters)(self, that)
/**
* Same as `testUnaryEquivalence` but for functions of type `Predicate<A>`.
* @param a - An arbitrary for the function argument type `A`.
* @param parameters - Optional [fast-check parameters](https://fast-check.dev/api-reference/interfaces/Parameters.html).
* @returns True if no counterexample found, else false.
* @category equivalence
*/
export const testPredicateEquivalence = <A>(
a: fc.Arbitrary<A>,
parameters?: fc.Parameters<A>,
) => testUnaryEquivalence(a, BO.Equivalence, parameters)
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