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fp-go/v2/option/testing/laws.go
Dr. Carsten Leue 600521b220 fix: refactor
Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>
2025-11-11 11:01:49 +01:00

103 lines
2.5 KiB
Go

// Copyright (c) 2025 IBM Corp.
// All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package testing
import (
"testing"
EQ "github.com/IBM/fp-go/v2/eq"
L "github.com/IBM/fp-go/v2/internal/monad/testing"
O "github.com/IBM/fp-go/v2/option"
)
// AssertLaws asserts the monad laws for the Option monad.
// This function verifies that Option satisfies the functor, applicative, and monad laws.
//
// The laws tested include:
// - Functor laws: identity and composition
// - Applicative laws: identity, composition, homomorphism, and interchange
// - Monad laws: left identity, right identity, and associativity
//
// Parameters:
// - t: testing instance
// - eqa, eqb, eqc: equality predicates for types A, B, and C
// - ab: a function from A to B for testing
// - bc: a function from B to C for testing
//
// Returns a function that takes a value of type A and returns true if all laws hold.
//
// Example:
//
// func TestOptionLaws(t *testing.T) {
// eqInt := eq.FromStrictEquals[int]()
// eqString := eq.FromStrictEquals[string]()
// eqBool := eq.FromStrictEquals[bool]()
//
// ab := strconv.Itoa
// bc := func(s string) bool { return len(s) > 0 }
//
// assert := AssertLaws(t, eqInt, eqString, eqBool, ab, bc)
// assert(42) // verifies laws hold for value 42
// }
func AssertLaws[A, B, C any](t *testing.T,
eqa EQ.Eq[A],
eqb EQ.Eq[B],
eqc EQ.Eq[C],
ab func(A) B,
bc func(B) C,
) func(a A) bool {
return L.AssertLaws(t,
O.Eq(eqa),
O.Eq(eqb),
O.Eq(eqc),
O.Of[A],
O.Of[B],
O.Of[C],
O.Of[func(A) A],
O.Of[func(A) B],
O.Of[func(B) C],
O.Of[func(func(A) B) B],
O.MonadMap[A, A],
O.MonadMap[A, B],
O.MonadMap[A, C],
O.MonadMap[B, C],
O.MonadMap[func(B) C, func(func(A) B) func(A) C],
O.MonadChain[A, A],
O.MonadChain[A, B],
O.MonadChain[A, C],
O.MonadChain[B, C],
O.MonadAp[A, A],
O.MonadAp[B, A],
O.MonadAp[C, B],
O.MonadAp[C, A],
O.MonadAp[B, func(A) B],
O.MonadAp[func(A) C, func(A) B],
ab,
bc,
)
}