TileContentBuilder - exception adding text on Wide tile

[supermartzin]

Describe the bug

When creating Live tile content via TileContentBuilder, I always get NullReferenceException when setting the text on Wide sized tile.
❗ This only happens when trying to create Wide Live tile alone ❗ When Medium tile is present, it's all working.

• Is this bug a regression in the toolkit?
  No, it's a bug on the current version as well as in the current repository code.

Steps to Reproduce

• Can this be reproduced in the Sample App?
  No, because in the sample app you're creating Live tile content for all sizes: Medium, Wide, and Large, this only happens when you want to set solely Wide Live tile content.

Create sample Live tile content with TileContentBuilder, but only for Wide tile size, like in the sample code below and try to run it:

var builder = new TileContentBuilder();

builder.AddTile(TileSize.Wide)
           .SetTextStacking(TileTextStacking.Top)
           .AddText("Header", hintStyle: AdaptiveTextStyle.Base)
           .AddText("Subtitle", hintStyle: AdaptiveTextStyle.CaptionSubtle)
           .SetBranding(TileBranding.NameAndLogo);
            
TileUpdateManager.CreateTileUpdaterForApplication().Update(new TileNotification(builder.Content.GetXml()));

Expected behavior

Screenshots

Bug in code

According to NullReferenceException, the core issue was thrown from this method:
TileContentBuilder.AddAdaptiveTileVisualChild(ITileBindingContentAdaptiveChild child, TileSize size)

After inspecting the code of that method in this repository, I think I found what's causing it.
It's this line in the method, it's incorrectly getting the content from MediumTile instead of WideTile. As MediumTile is not set in my case, the exception is thrown.

if (size.HasFlag(TileSize.Wide) && WideTile != null && GetAdaptiveTileContent(--> MediumTile <--) != null)
{
    GetAdaptiveTileContent(WideTile).Children.Add(child);
}

Environment

NuGet Package(s): Microsoft.Toolkit.Uwp.Notifications

Package Version(s): 7.0.1

Windows 10 Build Number:

• Fall Creators Update (16299)
• April 2018 Update (17134)
• October 2018 Update (17763)
• May 2019 Update (18362)
• May 2020 Update (19041)
• October 2020 Update (19042)
• Insider Build (build number: )

App min and target version:

• Fall Creators Update (16299)
• April 2018 Update (17134)
• October 2018 Update (17763) -- MIN
• May 2019 Update (18362)
• May 2020 Update (19041) -- TARGET
• Insider Build (xxxxx)

Device form factor:

• Desktop
• Xbox
• Surface Hub
• IoT

Visual Studio

• 2017 (version: )
• 2019 (version: 16.9.4)
• 2019 Preview (version: )

Additional context

Hello supermartzin, thank you for opening an issue with us!

I have automatically added a "needs triage" label to help get things started. Our team will analyze and investigate the issue, and escalate it to the relevant team if possible. Other community members may also look into the issue and provide feedback 🙌

[michael-hawker]

FYI @andrewleader

[andrewleader]

Thanks for reporting this @supermartzin!

Any chance you're also interested in fixing it? 😊 If you don't have the time or ability, no worries, but figured I'd ask first as it seems like you've already poked around in the code some and I'm not sure I'll be able to get to this super soon. Let me know if you're interested in trying to fix it!

[supermartzin]

Hi @andrewleader, no problem!
Just fork the repo, fix the problem, and create PR? Or any other steps to follow? 🙂

Thanks!

[andrewleader]

That's it! Thanks @supermartzin!! 😊 Let me know if you have any questions! There are also some unit tests inside UnitTests.Notifications.Shared, it'd be nice if you add a unit test alongside the fix to cover this case (clearly we were missing one previously for this case).

[michael-hawker]

Thanks @supermartzin 🎉, we have more info on anything you should need to get contributing to the project in our wiki. Let us know if you need any help, main thing is usually just to create a feature branch in your fork.