Minor build fixes/cleanup

Tests/FoundationEssentialsTests/LockedStateTests.swift

@@ -14,7 +14,9 @@
 import TestSupport
 #endif
 
-#if canImport(FoundationEssentials)
+#if FOUNDATION_FRAMEWORK
+@testable import Foundation
+#else
 @testable import FoundationEssentials
 #endif
 
@@ -105,6 +107,24 @@ final class LockedStateTests : XCTestCase {
 
         assertLockNotHeld(lockedState, "Lock was not properly released by withLockExtendingLifetimeOfState()")
     }
+
+    func testWithLockExtendingLifespanDoesExtendLifetimeOfState() {
+        weak var state: TestObject?
+        let lockedState: LockedState<TestObject>
+
+        (state, lockedState) = {
+            let state = TestObject()
+            return (state, LockedState(initialState: state))
+        }()
+
+        lockedState.withLockExtendingLifetimeOfState { state in
+            weak var oldState = state
+            state = TestObject()
+            XCTAssertNotNil(oldState, "State object lifetime was not extended after reassignment within body")
+        }
+
+        XCTAssertNil(state, "State object lifetime was extended beyond end of call")
+    }
 }
 
 /// Assert that the locked state is not currently locked.