Merge pull request #96 from Infomaniak/xor-collection-id

feat: Identifiable collection

Sources/InfomaniakCore/Extensions/Collection+Identity.swift

@@ -0,0 +1,31 @@
+/*
+ Infomaniak Core - iOS
+ Copyright (C) 2023 Infomaniak Network SA
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import Foundation
+import SwiftUI
+
+@available(iOS 13.0, *)
+public extension Collection where Element: Identifiable {
+    /// Compute a stable id for the given collection
+    func collectionId(baseId: AnyHashable? = nil) -> Int {
+        var hasher = Hasher()
+        hasher.combine(baseId)
+        forEach { hasher.combine($0.id) }
+        return hasher.finalize()
+    }
+}

Tests/InfomaniakCoreTests/Extensions/UTCollection+Identity.swift

@@ -0,0 +1,107 @@
+/*
+ Infomaniak Core - iOS
+ Copyright (C) 2023 Infomaniak Network SA
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import InfomaniakCore
+import XCTest
+
+extension Int: Identifiable {
+    public var id: Int {
+        return self
+    }
+}
+
+@available(iOS 13.0, *)
+final class UTCollectionIdentity: XCTestCase {
+    func testIntSameArraySameHash() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 4]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId()
+        let rhsId = rhsArray.collectionId()
+
+        // THEN
+        XCTAssertEqual(lhsId, rhsId, "We expect the ids to be the same")
+    }
+
+    func testIntSameArraySameHashWithBase() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 4]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId(baseId: 10)
+        let rhsId = rhsArray.collectionId(baseId: 10)
+
+        // THEN
+        XCTAssertEqual(lhsId, rhsId, "We expect the ids to be the same")
+    }
+
+    func testIntReversedArrayDifferentHash() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 4].reversed()
+
+        // WHEN
+        let lhsId = lhsArray.collectionId()
+        let rhsId = rhsArray.collectionId()
+
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+
+    func testIntDifferentArrayDifferentHash() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 5]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId()
+        let rhsId = rhsArray.collectionId()
+
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+
+    func testIntDifferentArrayDifferentHashWithBase() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 5]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId(baseId: 10)
+        let rhsId = rhsArray.collectionId(baseId: 10)
+
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+
+    func testIntDifferentArrayDifferentHashWithDifferentBase() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 5]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId(baseId: 10)
+        let rhsId = rhsArray.collectionId(baseId: 11)
+
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+}