diff --git a/UnitTests/Sources/NavigationSplitCoordinatorTests.swift b/UnitTests/Sources/NavigationSplitCoordinatorTests.swift
index cc5b7181e0..cc12ea20b6 100644
--- a/UnitTests/Sources/NavigationSplitCoordinatorTests.swift
+++ b/UnitTests/Sources/NavigationSplitCoordinatorTests.swift
@@ -99,6 +99,52 @@ class NavigationSplitCoordinatorTests: XCTestCase {
         assertCoordinatorsEqual(someOtherSheetCoordinator, navigationSplitCoordinator.sheetCoordinator)
     }
     
+    func testFullScreenCover() {
+        let sidebarCoordinator = SomeTestCoordinator()
+        navigationSplitCoordinator.setSidebarCoordinator(sidebarCoordinator)
+        let detailCoordinator = SomeTestCoordinator()
+        navigationSplitCoordinator.setDetailCoordinator(detailCoordinator)
+        
+        let fullScreenCoordinator = SomeTestCoordinator()
+        navigationSplitCoordinator.setFullScreenCoverCoordinator(fullScreenCoordinator)
+        
+        assertCoordinatorsEqual(sidebarCoordinator, navigationSplitCoordinator.sidebarCoordinator)
+        assertCoordinatorsEqual(detailCoordinator, navigationSplitCoordinator.detailCoordinator)
+        assertCoordinatorsEqual(fullScreenCoordinator, navigationSplitCoordinator.fullScreenCoverCoordinator)
+        
+        navigationSplitCoordinator.setFullScreenCoverCoordinator(nil)
+        
+        assertCoordinatorsEqual(sidebarCoordinator, navigationSplitCoordinator.sidebarCoordinator)
+        assertCoordinatorsEqual(detailCoordinator, navigationSplitCoordinator.detailCoordinator)
+        XCTAssertNil(navigationSplitCoordinator.fullScreenCoverCoordinator)
+    }
+    
+    func testOverlay() {
+        let sidebarCoordinator = SomeTestCoordinator()
+        navigationSplitCoordinator.setSidebarCoordinator(sidebarCoordinator)
+        let detailCoordinator = SomeTestCoordinator()
+        navigationSplitCoordinator.setDetailCoordinator(detailCoordinator)
+        
+        let overlayCoordinator = SomeTestCoordinator()
+        navigationSplitCoordinator.setOverlayCoordinator(overlayCoordinator)
+        
+        assertCoordinatorsEqual(sidebarCoordinator, navigationSplitCoordinator.sidebarCoordinator)
+        assertCoordinatorsEqual(detailCoordinator, navigationSplitCoordinator.detailCoordinator)
+        assertCoordinatorsEqual(overlayCoordinator, navigationSplitCoordinator.overlayCoordinator)
+        
+        // The coordinator should still be retained when changing the presentation mode.
+        navigationSplitCoordinator.setOverlayPresentationMode(.minimized)
+        assertCoordinatorsEqual(overlayCoordinator, navigationSplitCoordinator.overlayCoordinator)
+        navigationSplitCoordinator.setOverlayPresentationMode(.fullScreen)
+        assertCoordinatorsEqual(overlayCoordinator, navigationSplitCoordinator.overlayCoordinator)
+        
+        navigationSplitCoordinator.setOverlayCoordinator(nil)
+        
+        assertCoordinatorsEqual(sidebarCoordinator, navigationSplitCoordinator.sidebarCoordinator)
+        assertCoordinatorsEqual(detailCoordinator, navigationSplitCoordinator.detailCoordinator)
+        XCTAssertNil(navigationSplitCoordinator.overlayCoordinator)
+    }
+    
     func testSidebarReplacementCallbacks() {
         let sidebarCoordinator = SomeTestCoordinator()
         
@@ -135,6 +181,43 @@ class NavigationSplitCoordinatorTests: XCTestCase {
         waitForExpectations(timeout: 1.0)
     }
     
+    func testFullScreenCoverDismissalCallback() {
+        let fullScreenCoordinator = SomeTestCoordinator()
+        
+        let expectation = expectation(description: "Wait for callback")
+        navigationSplitCoordinator.setFullScreenCoverCoordinator(fullScreenCoordinator) {
+            expectation.fulfill()
+        }
+        
+        navigationSplitCoordinator.setFullScreenCoverCoordinator(nil)
+        waitForExpectations(timeout: 1.0)
+    }
+    
+    func testOverlayDismissalCallback() {
+        let overlayCoordinator = SomeTestCoordinator()
+        
+        let expectation = expectation(description: "Wait for callback")
+        navigationSplitCoordinator.setOverlayCoordinator(overlayCoordinator) {
+            expectation.fulfill()
+        }
+        
+        navigationSplitCoordinator.setOverlayCoordinator(nil)
+        waitForExpectations(timeout: 1.0)
+    }
+    
+    func testOverlayDismissalCallbackWhenChangingMode() {
+        let overlayCoordinator = SomeTestCoordinator()
+        
+        let expectation = expectation(description: "Wait for callback")
+        expectation.isInverted = true
+        navigationSplitCoordinator.setOverlayCoordinator(overlayCoordinator) {
+            expectation.fulfill()
+        }
+        
+        navigationSplitCoordinator.setOverlayPresentationMode(.minimized)
+        waitForExpectations(timeout: 1.0)
+    }
+    
     func testEmbeddedStackPresentsSheetThroughSplit() {
         let sidebarNavigationStackCoordinator = NavigationStackCoordinator(navigationSplitCoordinator: navigationSplitCoordinator)
         sidebarNavigationStackCoordinator.setRootCoordinator(SomeTestCoordinator())