Frameworks/Feed/Bundle/Sources/Logic/View Models/FeedListViewModel.swift

@@ -116,16 +116,19 @@ extension FeedListViewController {
         }
         
         func item(for index: Int) -> Review? {
-            guard
-                !items.isEmpty,
-                index < items.count
-            else {
+            guard !items.isEmpty else {
                 return nil
             }
             
-            return isWordsShowing
-                ? items[index - 1]
-                : items[index]
+            let indexToUse = isWordsShowing
+                ? index - 1
+                : index
+            
+            guard indexToUse < items.count else {
+                return nil
+            }
+            
+            return items[indexToUse]
         }
         
         func openItem(at index: Int) {

Frameworks/Feed/Test/Tests/View Models/FeedListViewModelTests.swift

@@ -15,6 +15,9 @@ import XCTest
 
 final class FeedListViewModelTests: XCTestCase {
     
+    // MARK: Constants
+    private let coordination: FeedListCoordinationSpy = .init()
+
     // MARK: Properties
     private var sut: FeedListViewController.ViewModel!
     
@@ -24,7 +27,7 @@ final class FeedListViewModelTests: XCTestCase {
     override func setUp() async throws {
         sut = .init(
             configuration: .init(session: .mock),
-            coordination: nil
+            coordination: coordination
         )
     }
     
@@ -454,7 +457,7 @@ final class FeedListViewModelTests: XCTestCase {
         let item = sut.item(for: 1)
         
         // THEN
-        XCTAssertNil(item)
+        XCTAssertNotNil(item)
     }
     
     func testItemFor_indexOutOfBounds_withFilteredItems() async {
@@ -491,4 +494,88 @@ final class FeedListViewModelTests: XCTestCase {
         XCTAssertNil(item)
     }
     
+    func testOpenItemAt_index_withSomeItems() async {
+        // GIVEN
+        MockURLProtocol.response = .init(
+            statusCode: 200,
+            object: Feed(entries: .sample)
+        )
+        
+        // WHEN
+        await sut.fetch()
+        
+        sut.openItem(at: 0)
+        
+        // THEN
+        XCTAssertTrue(coordination.itemOpened)
+    }
+    
+    func testOpenItemAt_indexOutOfBounds_withSomeItems() async {
+        // GIVEN
+        MockURLProtocol.response = .init(
+            statusCode: 200,
+            object: Feed(entries: .sample)
+        )
+        
+        // WHEN
+        await sut.fetch()
+        
+        sut.openItem(at: 10)
+        
+        // THEN
+        XCTAssertFalse(coordination.itemOpened)
+    }
+    
+    func testOpenItemAt_index_withFilteredItems() async {
+        // GIVEN
+        MockURLProtocol.response = .init(
+            statusCode: 200,
+            object: Feed(entries: .sample)
+        )
+        
+        // WHEN
+        sut.filter(by: .only1Star)
+        
+        await sut.fetch()
+
+        sut.openItem(at: 1)
+
+        // THEN
+        XCTAssertTrue(coordination.itemOpened)
+    }
+    
+    func testOpenItemAt_indexOutOfBounds_withFilteredItems() async {
+        // GIVEN
+        MockURLProtocol.response = .init(
+            statusCode: 200,
+            object: Feed(entries: .sample)
+        )
+        
+        // WHEN
+        sut.filter(by: .only1Star)
+        
+        await sut.fetch()
+
+        sut.openItem(at: 2)
+
+        // THEN
+        XCTAssertFalse(coordination.itemOpened)
+    }
+    
+    func testOpenItemAt_index_withNoItems() async {
+        // GIVEN
+        MockURLProtocol.response = .init(
+            statusCode: 200,
+            object: Feed(entries: .none)
+        )
+        
+        // WHEN
+        await sut.fetch()
+        
+        sut.openItem(at: 0)
+
+        // THEN
+        XCTAssertFalse(coordination.itemOpened)
+    }
+    
 }