Add a test for #6294

This case was fixed by 2992f8e - this commit just adds a test to verify
the fix.

test/Microsoft.AspNetCore.Mvc.FunctionalTests/RazorPagesTest.cs

@@ -1011,6 +1011,19 @@ Microsoft.AspNetCore.Mvc.ViewFeatures.ViewDataDictionary`1[AspNetCore._InjectedP
             Assert.StartsWith(expected, response.Trim());
         }
 
+        [Fact]
+        public async Task Page_WithSection_CanAccessModel()
+        {
+            // Arrange
+            var expected = "Value is 17";
+
+            // Act
+            var response = await Client.GetStringAsync("/Pages/Section");
+
+            // Assert
+            Assert.StartsWith(expected, response.Trim());
+        }
+
         private async Task AddAntiforgeryHeaders(HttpRequestMessage request)
         {
             var getResponse = await Client.GetAsync(request.RequestUri);

test/WebSites/RazorPagesWebSite/Pages/Section/Index.cshtml

@@ -0,0 +1,10 @@
+@page
+@{ 
+    Layout = "_Layout";
+}
+@functions {
+    public int MyValue { get; set; } = 17;
+}
+@section mysection {
+    Value is @Model.MyValue
+}

test/WebSites/RazorPagesWebSite/Pages/Section/_Layout.cshtml

@@ -0,0 +1 @@
+@RenderSection("mysection")