Prepare for nullability changes in ASP.NET 6

ASP.NET 6.0 contains some nullability changes [1] that, in
the absence of these null-forgiving operators, would generate CS8602 and
CS8604 warnings after upgrading.

[1] e.g. aspnet/Announcements#444 and
dotnet/aspnetcore#31338

src/Buttercup.Web.Tests/Controllers/AccountControllerTests.cs

@@ -73,7 +73,7 @@ public async Task ChangePasswordPostAddsErrorWhenCurrentPasswordIsIncorrect()
 
             var errors = fixture
                 .AccountController
-                .ModelState[nameof(ChangePasswordViewModel.CurrentPassword)]
+                .ModelState[nameof(ChangePasswordViewModel.CurrentPassword)]!
                 .Errors;
 
             var error = Assert.Single(errors);

src/Buttercup.Web.Tests/Controllers/AuthenticationControllerTests.cs

@@ -208,7 +208,7 @@ public async Task SignInPostAddsErrorWhenAuthenticationFails()
             await fixture.SignInPost();
 
             var error = Assert.Single(
-                fixture.AuthenticationController.ModelState[string.Empty].Errors);
+                fixture.AuthenticationController.ModelState[string.Empty]!.Errors);
 
             Assert.Equal("translated-wrong-email-or-password-error", error.ErrorMessage);
         }
@@ -313,7 +313,7 @@ public void SignOutSetsCacheControlHeader()
 
             var result = fixture.AuthenticationController.SignOut();
 
-            var cacheControlHeader = fixture.HttpContext.Response.GetTypedHeaders().CacheControl;
+            var cacheControlHeader = fixture.HttpContext.Response.GetTypedHeaders().CacheControl!;
 
             Assert.True(cacheControlHeader.NoCache);
             Assert.True(cacheControlHeader.NoStore);

src/Buttercup.Web.Tests/Controllers/RecipesControllerTests.cs

@@ -94,7 +94,7 @@ public async Task NewPostAddsRecipeAndRedirectsToShowPage()
 
             var redirectResult = Assert.IsType<RedirectToActionResult>(result);
             Assert.Equal(nameof(RecipesController.Show), redirectResult.ActionName);
-            Assert.Equal(5L, redirectResult.RouteValues["id"]);
+            Assert.Equal(5L, redirectResult.RouteValues!["id"]);
         }
 
         [Fact]
@@ -162,7 +162,7 @@ public async Task EditPostUpdatesRecipeAndRedirectsToShowPage()
 
             var redirectResult = Assert.IsType<RedirectToActionResult>(result);
             Assert.Equal(nameof(RecipesController.Show), redirectResult.ActionName);
-            Assert.Equal(3L, redirectResult.RouteValues["id"]);
+            Assert.Equal(3L, redirectResult.RouteValues!["id"]);
         }
 
         [Fact]

src/Buttercup.Web.Tests/Filters/EnsureSignedOutAttributeTests.cs

@@ -34,7 +34,7 @@ public void OnActionExecutingRedirectsToSignOutIfAuthenticated()
 
             Assert.Equal("Authentication", redirectResult.ControllerName);
             Assert.Equal(nameof(AuthenticationController.SignOut), redirectResult.ActionName);
-            Assert.Equal(new PathString(RequestPath), redirectResult.RouteValues["returnUrl"]);
+            Assert.Equal(new PathString(RequestPath), redirectResult.RouteValues!["returnUrl"]);
         }
 
         [Fact]
@@ -43,7 +43,7 @@ public void OnActionExecutingSetsCacheControlHeader()
             var actionExecutingContext = CallOnActionExecuting(null);
 
             var cacheControlHeader =
-                actionExecutingContext.HttpContext.Response.GetTypedHeaders().CacheControl;
+                actionExecutingContext.HttpContext.Response.GetTypedHeaders().CacheControl!;
 
             Assert.True(cacheControlHeader.NoCache);
             Assert.True(cacheControlHeader.NoStore);
@@ -64,7 +64,7 @@ private static ActionExecutingContext CallOnActionExecuting(string? authenticati
             var actionExecutingContext = new ActionExecutingContext(
                 new(httpContext, new(), new()),
                 Array.Empty<IFilterMetadata>(),
-                new Dictionary<string, object>(),
+                new Dictionary<string, object?>(),
                 new());
 
             new EnsureSignedOutAttribute().OnActionExecuting(actionExecutingContext);

src/Buttercup.Web.Tests/TestUtils/ListLogger.cs

@@ -29,8 +29,8 @@ public void Log<TState>(
             LogLevel logLevel,
             EventId eventId,
             TState state,
-            Exception exception,
-            Func<TState, Exception, string> formatter) =>
+            Exception? exception,
+            Func<TState, Exception?, string> formatter) =>
             this.entries.Add(new(logLevel, eventId, formatter(state, exception), state, exception));
 
         private sealed class NullDisposable : IDisposable

src/Buttercup.Web.Tests/TestUtils/LogEntry.cs

@@ -4,5 +4,5 @@
 namespace Buttercup.Web.TestUtils
 {
     public record LogEntry(
-        LogLevel LogLevel, EventId EventId, string Message, object? State, Exception Exception);
+        LogLevel LogLevel, EventId EventId, string Message, object? State, Exception? Exception);
 }

src/Buttercup.Web/Views/Account/Show.cshtml

@@ -11,7 +11,7 @@
   <div class="account-overview__item">
     <div class="account-overview__item-content">
       <div class="account-overview__item-label">@Localizer["Label_Name"]</div>
-      <div class="account-overview__item-data">@Model.Name</div>
+      <div class="account-overview__item-data">@Model!.Name</div>
     </div>
   </div>
   <div class="account-overview__item">

src/Buttercup.Web/Views/Authentication/RequestPasswordResetConfirmation.cshtml

@@ -4,4 +4,4 @@
   ViewData["Title"] = Localizer["Title_ResetPassword"];
 }
 <h1>@Localizer["Title_ResetPassword"]</h1>
-<p>@Localizer["Message_PasswordResetLinkSent", @Model.Email]</p>
+<p>@Localizer["Message_PasswordResetLinkSent", @Model!.Email!]</p>

src/Buttercup.Web/Views/Error/Error.cshtml

@@ -7,7 +7,7 @@
 <h1>@Localizer["Title_Error"]</h1>
 <p>@Localizer["Message_GeneralError"]</p>
 
-@if (Model.ShowRequestId)
+@if (Model!.ShowRequestId)
 {
     <p>
         <strong>@Localizer["Label_RequestId"]:</strong> <code>@Model.RequestId</code>

src/Buttercup.Web/Views/Home/Index.cshtml

@@ -7,7 +7,7 @@
   <section class="home-page__recipe-list">
     <h1>@Localizer["Heading_RecentlyAdded"]</h1>
     <ul>
-      @foreach (var recipe in Model.RecentlyAddedRecipes!)
+      @foreach (var recipe in Model!.RecentlyAddedRecipes!)
       {
         <li><a asp-controller="Recipes" asp-action="Show" asp-route-id="@recipe.Id">@recipe.Title</a></li>
       }

src/Buttercup.Web/Views/Recipes/Delete.cshtml

@@ -1,12 +1,12 @@
 @inject IViewLocalizer Localizer
 @model Recipe
 @{
-  ViewData["Title"] = Localizer["Title_DeleteRecipe", Model.Title];
+  ViewData["Title"] = Localizer["Title_DeleteRecipe", Model!.Title!];
 }
 <h1>@Localizer["Heading_DeleteRecipe"]</h1>
 <form method="post">
   <input type="hidden" asp-for="Revision">
-  <p>@Localizer["Message_DeleteConfirmation", Model.Title]</p>
+  <p>@Localizer["Message_DeleteConfirmation", Model.Title!]</p>
   <div class="button-bar">
     <button class="critical-push-button">@Localizer["Label_DeleteForever"]</button>
     <a class="push-button" asp-action="Show" asp-route-id="@Model.Id">@Localizer["Label_Cancel"]</a>

src/Buttercup.Web/Views/Recipes/Edit.cshtml

@@ -1,7 +1,7 @@
 @inject IViewLocalizer Localizer
 @model RecipeEditModel
 @{
-  ViewData["Title"] = Localizer["Title_EditRecipe", Model.Title];
+  ViewData["Title"] = Localizer["Title_EditRecipe", Model!.Title!];
 }
 <h1>@Localizer["Heading_EditRecipe"]</h1>
 <form method="post">

src/Buttercup.Web/Views/Recipes/Index.cshtml

@@ -20,7 +20,7 @@
     </tr>
   </thead>
   <tbody>
-    @foreach (var recipe in Model)
+    @foreach (var recipe in Model!)
     {
       <tr>
         <td><a asp-action="Show" asp-route-id="@recipe.Id">@recipe.Title</a></td>

src/Buttercup.Web/Views/Recipes/Show.cshtml

@@ -2,7 +2,7 @@
 @inject IViewLocalizer Localizer
 @model Recipe
 @{
-  ViewData["Title"] = Model.Title;
+  ViewData["Title"] = Model!.Title;
 }
 <h1>@Model.Title</h1>