Adding functional tests for @namespace

samples/MvcSandbox/Pages/_ViewImports.cshtml

@@ -1,2 +1,2 @@
-@using MvcSandbox
+@namespace MvcSandbox.Pages
 @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

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

@@ -0,0 +1,53 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.FunctionalTests
+{
+    public class RazorPagesNamespaceTest : IClassFixture<MvcTestFixture<RazorPagesWebSite.Startup>>
+    {
+        public RazorPagesNamespaceTest(MvcTestFixture<RazorPagesWebSite.Startup> fixture)
+        {
+            Client = fixture.Client;
+        }
+
+        public HttpClient Client { get; }
+
+        [Fact]
+        public async Task Page_DefaultNamespace_IfUnset()
+        {
+            // Arrange & Act
+            var content = await Client.GetStringAsync("http://localhost/DefaultNamespace");
+
+            // Assert
+            Assert.Equal("AspNetCore", content.Trim());
+        }
+        
+        [Fact]
+        public async Task Page_ImportedNamespace_UsedFromViewImports()
+        {
+            // Arrange & Act
+            var content = await Client.GetStringAsync("http://localhost/Pages/Namespace/Nested/Folder");
+
+            // Assert
+            Assert.Equal("CustomNamespace.Nested.Folder", content.Trim());
+        }
+        
+        [Fact]
+        public async Task Page_OverrideNamespace_SetByPage()
+        {
+            // Arrange & Act
+            var content = await Client.GetStringAsync("http://localhost/Pages/Namespace/Nested/Override");
+
+            // Assert
+            Assert.Equal("Override", content.Trim());
+        }
+    }
+}

test/WebSites/RazorPagesWebSite/DefaultNamespace.cshtml

@@ -0,0 +1,2 @@
+@page
+@(GetType().Namespace)

test/WebSites/RazorPagesWebSite/Pages/Namespace/Nested/Folder/Index.cshtml

@@ -0,0 +1,2 @@
+@page
+@(GetType().Namespace)

test/WebSites/RazorPagesWebSite/Pages/Namespace/Nested/Override/Index.cshtml

@@ -0,0 +1,3 @@
+@page
+@namespace Override
+@(GetType().Namespace)

test/WebSites/RazorPagesWebSite/Pages/Namespace/_ViewImports.cshtml

@@ -0,0 +1 @@
+@namespace CustomNamespace

test/WebSites/RazorPagesWebSite/Pages/_ViewImports.cshtml

@@ -0,0 +1 @@
+@namespace RazorPagesWebSite.Pages