Add preview option to shared container

Author: hmlongco

CHANGELOG

@@ -1,5 +1,10 @@
 # Factory Changelog
 
+## 2.4.12
+
+* Add preview convenience function to SharedContainer for SwiftUI Previews
+* New mechanism to enable StrictConcurrency in targets
+
 ## 2.4.11
 
 * Pulled evolution support due to SPM .unsafe flags problem - Issue #289

Sources/Factory/Factory/Containers.swift

@@ -26,6 +26,10 @@
 
 import Foundation
 
+#if canImport(SwiftUI)
+import SwiftUI
+#endif
+
 // MARK: - Container
 
 /// This is the default Container provided for your convenience by Factory.
@@ -81,6 +85,34 @@ public protocol SharedContainer: ManagedContainer {
 
 }
 
+#if canImport(SwiftUI)
+/// Defines the default factory helpers for shared containers
+extension SharedContainer {
+    /// Defines a preview convenience function to allow easy shared container transformation in SwiftUI Previews.
+    /// ```swift
+    /// #Preview {
+    ///     Container.preview {
+    ///         $0.requestUsers.register { MockAsyncRequest { User.mockUsers } }
+    ///     }
+    ///     MainView()
+    /// }
+    /// ```
+    /// Without it you'd need something like...
+    /// ```swift
+    /// #Preview {
+    ///     let _ = Container.shared.with {
+    ///         $0.requestUsers.register { MockAsyncRequest { User.mockUsers } }
+    ///     }
+    ///     MainView()
+    /// }
+    /// ```
+    public static func preview(_ transform: (Self) -> Void) -> EmptyView {
+        transform(shared)
+        return EmptyView()
+    }
+}
+#endif
+
 // MARK: - ManagedContainer
 
 /// ManagedContainer defines the core protocol all Containers must adopt.

Sources/Factory/Factory/Key.swift

@@ -57,23 +57,23 @@ internal struct FactoryKey: Hashable {
 //
 // Obtaining and using the class name string directly on every call results in code that's 2-3x slower.
 private func globalIdentifier(for type: Any.Type) -> ObjectIdentifier {
-    defer { globalVariableLock.unlock() }
-    globalVariableLock.lock()
-    let requestedTypeID = ObjectIdentifier(type)
-    // if known return it
-    if let knownID = globalKnownIdentifierTable[requestedTypeID] {
-        return knownID
+    globalVariableLock.withLock {
+        let requestedTypeID = ObjectIdentifier(type)
+        // if known return it
+        if let knownID = globalKnownIdentifierTable[requestedTypeID] {
+            return knownID
+        }
+        // this is what we're bypassing. extremely slow runtime function.
+        let name = String(reflecting: type)
+        // magic happens here, if name is already known then get original key for it
+        let id = globalNameToIdentifierTable[name, default: requestedTypeID]
+        // and save it so we don't have to do this again
+        globalKnownIdentifierTable[requestedTypeID] = id
+        #if DEBUG
+        globalIdentifierToNameTable[id] = name
+        #endif
+        return id
     }
-    // this is what we're bypassing. extremely slow runtime function.
-    let name = String(reflecting: type)
-    // magic happens here, if name is already known then get original key for it
-    let id = globalNameToIdentifierTable[name, default: requestedTypeID]
-    // and save it so we don't have to do this again
-    globalKnownIdentifierTable[requestedTypeID] = id
-    #if DEBUG
-    globalIdentifierToNameTable[id] = name
-    #endif
-    return id
 }
 
 // quickly denormalizes the requested type identifier to a known type identifier

Tests/FactoryTests/FactoryContainerTests.swift

@@ -1,6 +1,9 @@
 import XCTest
 @testable import Factory
 
+#if canImport(SwiftUI)
+import SwiftUI
+#endif
 
 final class FactoryContainerTests: XCTestCase {
 
@@ -56,6 +59,32 @@ final class FactoryContainerTests: XCTestCase {
         XCTAssertTrue(service3.text() == "MyService")
     }
 
+    func testWithFunction() throws {
+        let service1 = Container.shared.myServiceType()
+        XCTAssertTrue(service1.text() == "MyService")
+
+        Container.shared.with {
+            $0.myServiceType.register(factory: { MockService() })
+        }
+
+        let service2 = Container.shared.myServiceType()
+        XCTAssertTrue(service2.text() == "MockService")
+    }
+
+    #if canImport(SwiftUI)
+    func testPreviewFunction() throws {
+        let service1 = Container.shared.myServiceType()
+        XCTAssertTrue(service1.text() == "MyService")
+
+        let _ = Container.preview {
+            $0.myServiceType.register(factory: { MockService() })
+        }
+
+        let service2 = Container.shared.myServiceType()
+        XCTAssertTrue(service2.text() == "MockService")
+    }
+    #endif
+
     func testConvenienceFunctions() throws {
         XCTAssertNotNil(Container.shared.cachedCoverage())
         XCTAssertNotNil(Container.shared.graphCoverage())