Tusker/Packages/TuskerPreferences/Tests/TuskerPreferencesTests/PreferenceStoreTests.swift

//
//  PreferenceStoreTests.swift
//  TuskerPreferencesTests
//
//  Created by Shadowfacts on 4/12/24.
//

import XCTest
@testable import TuskerPreferences
import Combine

final class PreferenceStoreTests: XCTestCase {
    
    struct TestKey: PreferenceKey {
        static let defaultValue = false
    }
    
    final class TestStore: Codable, ObservableObject {
        private var _test = Preference<TestKey>()
        
        // the acutal subscript expects the enclosingInstance to be a PreferenceStore, so do it manually
        var test: Bool {
            get {
                Preference.get(enclosingInstance: self, storage: \._test)
            }
            set {
                Preference.set(enclosingInstance: self, storage: \._test, newValue: newValue)
            }
        }
        
        var testPublisher: some Publisher<TestKey.Value, Never> {
            _test.projectedValue
        }
        
        init() {
        }
        
        init(from decoder: any Decoder) throws {
            let container = try decoder.container(keyedBy: CodingKeys.self)
            self._test = try container.decode(Preference<TestKey>.self, forKey: .test)
        }
        
        enum CodingKeys: CodingKey {
            case test
        }
        
        func encode(to encoder: any Encoder) throws {
            var container = encoder.container(keyedBy: CodingKeys.self)
            try container.encode(self._test, forKey: .test)
        }
    }

    func testDecoding() throws {
        let decoder = JSONDecoder()
        let present = try decoder.decode(PreferenceCoding<TestStore>.self, from: Data("""
{"test": true}
""".utf8)).wrapped
        XCTAssertEqual(present.test, true)
        let absent = try decoder.decode(PreferenceCoding<TestStore>.self, from: Data("""
{}
""".utf8)).wrapped
        XCTAssertEqual(absent.test, false)
    }
    
    func testEncoding() throws {
        let store = TestStore()
        let encoder = JSONEncoder()
        XCTAssertEqual(String(data: try encoder.encode(PreferenceCoding(wrapped: store)), encoding: .utf8)!, """
{}
""")
        store.test = true
        XCTAssertEqual(String(data: try encoder.encode(PreferenceCoding(wrapped: store)), encoding: .utf8)!, """
{"test":true}
""")
        store.test = false
        XCTAssertEqual(String(data: try encoder.encode(PreferenceCoding(wrapped: store)), encoding: .utf8)!, """
{"test":false}
""")
    }
    
    func testPublisher() {
        let topLevel = expectation(description: "top level publisher")
        let specificPref = expectation(description: "preference publisher")
        // initial and on change
        specificPref.expectedFulfillmentCount = 2
        let store = TestStore()
        var cancellables = Set<AnyCancellable>()
        store.objectWillChange.sink {
            topLevel.fulfill()
            // fires on will change
            XCTAssertEqual(store.test, false)
        }.store(in: &cancellables)
        store.testPublisher.sink { _ in
            specificPref.fulfill()
        }.store(in: &cancellables)
        store.test = true
        wait(for: [topLevel, specificPref])
    }

}