add more tests. now at 98% coverage.

Author: jessesquires

Tests/Fakes/FakeLayout.swift

@@ -16,7 +16,8 @@ import Foundation
 import UIKit
 
 extension UICollectionViewCompositionalLayout {
-    static func fakeLayout(useNibViews: Bool = false) -> UICollectionViewCompositionalLayout {
+    static func fakeLayout(addSupplementaryViews: Bool = true,
+                           useNibViews: Bool = false) -> UICollectionViewCompositionalLayout {
         let fractionalWidth = CGFloat(0.5)
 
         // Supplementary Item
@@ -37,7 +38,10 @@ extension UICollectionViewCompositionalLayout {
         // Item
         let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(fractionalWidth),
                                               heightDimension: .fractionalHeight(1))
-        let item = NSCollectionLayoutItem(layoutSize: itemSize, supplementaryItems: [view])
+        let item = NSCollectionLayoutItem(
+            layoutSize: itemSize,
+            supplementaryItems: addSupplementaryViews ? [view] : []
+        )
 
         // Group
         let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1),

Tests/Fakes/FakeSupplementaryViewModel.swift

@@ -49,7 +49,7 @@ final class FakeSupplementaryView: UICollectionViewCell { }
 struct FakeHeaderViewModel: SupplementaryHeaderViewModel {
     let title = String.random
 
-    nonisolated var id: UniqueIdentifier { self.title }
+    nonisolated var id: UniqueIdentifier { "Header" }
 
     var expectationConfigureView: XCTestExpectation?
     func configure(view: FakeCollectionHeaderView) {
@@ -70,7 +70,7 @@ final class FakeCollectionHeaderView: UICollectionReusableView { }
 struct FakeFooterViewModel: SupplementaryFooterViewModel {
     let title = String.random
 
-    nonisolated var id: UniqueIdentifier { self.title }
+    nonisolated var id: UniqueIdentifier { "Footer" }
 
     var expectationConfigureView: XCTestExpectation?
     func configure(view: FakeCollectionFooterView) {

Tests/TestCollectionViewDriverReconfigure.swift

@@ -48,6 +48,39 @@ final class TestCollectionViewDriverReconfigure: UnitTestCase {
 
         self.keepDriverAlive(driver)
     }
+
+    @MainActor
+    func test_reconfigure_header_footer() {
+        let viewController = FakeCollectionViewController()
+        viewController.collectionView.setCollectionViewLayout(
+            UICollectionViewCompositionalLayout.fakeLayout(addSupplementaryViews: false),
+            animated: false
+        )
+
+        let driver = CollectionViewDriver(view: viewController.collectionView, options: .test())
+
+        // Initial header and footer
+        let header = FakeHeaderViewModel(expectationConfigureView: self.expectation(name: "initial_header"))
+        let footer = FakeFooterViewModel(expectationConfigureView: self.expectation(name: "initial_footer"))
+        let cells = [FakeNumberCellViewModel()]
+        let section = SectionViewModel(id: "id", cells: cells, header: header, footer: footer)
+        let model = CollectionViewModel(id: "id", sections: [section])
+
+        driver.update(viewModel: model)
+        self.simulateAppearance(viewController: viewController)
+        self.waitForExpectations()
+
+        // Update header and footer to be reconfigured
+        let updatedHeader = FakeHeaderViewModel(expectationConfigureView: self.expectation(name: "updated_header"))
+        let updatedFooter = FakeFooterViewModel(expectationConfigureView: self.expectation(name: "updated_footer"))
+        let updatedSection = SectionViewModel(id: "id", cells: cells, header: updatedHeader, footer: updatedFooter)
+        let updatedModel = CollectionViewModel(id: "id", sections: [updatedSection])
+
+        driver.update(viewModel: updatedModel)
+        self.waitForExpectations()
+
+        self.keepDriverAlive(driver)
+    }
 }
 
 private struct MyStaticCellViewModel: CellViewModel {