Fix root path regression for the Delivery API

src/Umbraco.Core/DeliveryApi/ApiContentPathResolver.cs

@@ -15,6 +15,7 @@ public ApiContentPathResolver(IRequestRoutingService requestRoutingService, IApi
         _apiPublishedContentCache = apiPublishedContentCache;
     }
 
+    [Obsolete("No longer used in V15. Scheduled for removal in V15.")]
     public virtual bool IsResolvablePath(string path)
     {
         // File requests will blow up with an downstream exception in GetRequiredPublishedSnapshot, which fails due to an UmbracoContext
@@ -30,7 +31,10 @@ public virtual bool IsResolvablePath(string path)
         return true;
     }
 
-    private static bool IsFileRequest(string path) => path.Split('/', StringSplitOptions.RemoveEmptyEntries).Last().Contains('.');
+    private static bool IsFileRequest(string path) => path
+        .Split('/', StringSplitOptions.RemoveEmptyEntries)
+        .LastOrDefault()?
+        .Contains('.') is true;
 
     public virtual IPublishedContent? ResolveContentPath(string path)
     {

src/Umbraco.Core/DeliveryApi/IApiContentPathResolver.cs

@@ -4,6 +4,7 @@ namespace Umbraco.Cms.Core.DeliveryApi;
 
 public interface IApiContentPathResolver
 {
+    [Obsolete("No longer used in V15. Scheduled for removal in V15.")]
     bool IsResolvablePath(string path) => true;
 
     IPublishedContent? ResolveContentPath(string path);

tests/Umbraco.Tests.UnitTests/Umbraco.Core/DeliveryApi/ApiContentPathResolverTests.cs

@@ -11,6 +11,7 @@ public class ApiContentPathResolverTests
     private const string TestPath = "/test/page";
 
     [TestCase(TestPath, true)]
+    [TestCase("/", true)]
     [TestCase("file.txt", false)]
     [TestCase("test/file.txt", false)]
     [TestCase("test/test2/file.txt", false)]
@@ -24,11 +25,12 @@ public void Can_Verify_Resolveable_Paths(string path, bool expected)
         Assert.AreEqual(expected, result);
     }
 
-    [Test]
-    public void Resolves_Content_For_Path()
+    [TestCase(TestPath)]
+    [TestCase("/")]
+    public void Resolves_Content_For_Path(string path)
     {
         var resolver = CreateResolver();
-        var result = resolver.ResolveContentPath(TestPath);
+        var result = resolver.ResolveContentPath(path);
         Assert.IsNotNull(result);
     }
 
@@ -40,7 +42,10 @@ private static ApiContentPathResolver CreateResolver()
             .Returns((string path) => path);
         var mockApiPublishedContentCache = new Mock<IApiPublishedContentCache>();
         mockApiPublishedContentCache
-            .Setup(x => x.GetByRoute(It.Is<string>(y => y == TestPath)))
+            .Setup(x => x.GetByRoute(TestPath))
+            .Returns(new Mock<IPublishedContent>().Object);
+        mockApiPublishedContentCache
+            .Setup(x => x.GetByRoute("/"))
             .Returns(new Mock<IPublishedContent>().Object);
         return new ApiContentPathResolver(mockRequestRoutingService.Object, mockApiPublishedContentCache.Object);
     }