Add PublishedDefaultTests

Tests/DefaultsTests/DefaultsPublishedDefaultTests.swift

@@ -0,0 +1,83 @@
+import XCTest
+import Combine
+import Defaults
+
+@available(macOS 11.0, iOS 15.0, tvOS 15.0, watchOS 8.0, *)
+private extension Defaults.Keys {
+    static let opacity = Key<Double>("opacity", default: 0.5)
+}
+
+@available(macOS 11.0, iOS 15.0, tvOS 15.0, watchOS 8.0, *)
+final class ViewModel: ObservableObject {
+    @PublishedDefault(.opacity) var opacity
+}
+
+@available(macOS 11.0, iOS 15.0, tvOS 15.0, watchOS 8.0, *)
+final class DefaultsPublishedDefaultTests: XCTestCase {
+    
+    var cancellables: [AnyCancellable] = []
+    
+    override func setUp() {
+        Defaults.removeAll()
+    }
+
+    override func tearDown() {
+        cancellables = []
+    }
+
+    func testObjectWillChange() {
+        let viewModel = ViewModel()
+        let objectExpectation = expectation(description: "Expected ObservableObject's fire")
+
+        viewModel.objectWillChange
+            .sink {
+                objectExpectation.fulfill()
+            }
+            .store(in: &cancellables)
+
+        viewModel.opacity = 1
+        waitForExpectations(timeout: 1)
+        
+        XCTAssertEqual(viewModel.opacity, 1)
+        XCTAssertEqual(Defaults[.opacity], 1)
+    }
+    
+    func testProjectValue() {
+        let viewModel = ViewModel()
+        let valueExpectation = expectation(description: "Expected Opacity Value")
+        var receivedValue: Double?
+        
+        viewModel.$opacity
+            // skip the initial value
+            .dropFirst()
+            .sink { newValue in
+                receivedValue = newValue
+                valueExpectation.fulfill()
+            }
+            .store(in: &cancellables)
+        
+        // Changing value via Defaults directly also fire the projecttedValue
+        Defaults[.opacity] = 1
+        waitForExpectations(timeout: 1)
+        XCTAssertEqual(receivedValue, 1)
+    }
+    
+    func testObservation() {
+        let viewModel = ViewModel()
+        // To enable Defaults observation, call observeDefaults.
+        viewModel.observeDefaults()
+        let objectExpectation = expectation(description: "Expected ObservableObject's fire")
+        
+        viewModel.objectWillChange
+            .sink {
+                objectExpectation.fulfill()
+            }
+            .store(in: &cancellables)
+
+        // Change value via Defaults instead of ObservableObject itself
+        Defaults[.opacity] = 1
+        waitForExpectations(timeout: 1)
+        
+        XCTAssertEqual(viewModel.opacity, 1)
+    }
+}