feat: Add Asset handling by linkdotnet · Pull Request #1847 · bUnit-dev/bUnit

linkdotnet · 2026-06-05T18:09:39Z

This fixes #1846

The basic idea is to have a convenient AddAsset method that passes a collection (just like AddParameter) to the Renderer - ComponentBase then can "grab" those.

This allow emulation of "@assets"

Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds support for seeding .NET 9+ ComponentBase.Assets in bUnit via a new AddAsset API, enabling tests to emulate @Assets/MapStaticAssets behavior.

Changes:

Introduces BunitContext.AddAsset and renderer-side asset storage to expose a ResourceAssetCollection through ComponentBase.Assets.
Adds new test assets/components and a new test suite covering indexer behavior, iteration, and custom properties.
Documents the feature (“Seeding static assets”) and links it from the docs TOC and changelog.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tests/bunit.tests/Rendering/AssetsTest.razor	New tests validating default/seeded `Assets` behavior via `AddAsset`.
tests/bunit.testassets/Assets/AssetsPropertiesComponent.razor	Test component for iterating assets and rendering properties.
tests/bunit.testassets/Assets/AssetsIterationComponent.razor	Test component for reading `label` property from assets and rendering labels.
tests/bunit.testassets/Assets/AssetsIndexerComponent.razor	Test component validating `Assets["key"]` indexer mapping.
src/bunit/Rendering/BunitRenderer.cs	Adds backing store + override for `Assets` and implements `AddAsset`.
src/bunit/BunitContext.cs	Exposes `AddAsset` on `BunitContext` delegating to the renderer.
docs/site/docs/toc.md	Adds link to new “Seeding static assets” documentation.
docs/site/docs/providing-input/seeding-assets.md	New documentation explaining how to seed `Assets` in tests.
CHANGELOG.md	Notes addition of `AddAsset` in “Added”.

+@code{
+    #if NET9_0_OR_GREATER
+}
+@using Bunit.TestAssets.Assets;
+@inherits BunitContext
+@code {


+@code{
+    #endif
+}


+	public void AddAsset(string url, string? label = null, params ResourceAssetProperty[] properties)
+	{
+		ArgumentException.ThrowIfNullOrEmpty(url);
+		ArgumentNullException.ThrowIfNull(properties);
+
+		var props = new List<ResourceAssetProperty>(properties.Length + 1);
+		if (label is not null)
+		{
+			props.Add(new ResourceAssetProperty("label", label));
+		}
+
+		props.AddRange(properties);


+		=> SubresourceNames = Assets
+			.Select(asset => asset.Properties?.SingleOrDefault(property => property.Name == "label")?.Value)
+			.OfType<string>()
+			.ToList();


+	/// <remarks>
+	/// Pass a <paramref name="label"/> to map a stable asset key to its (fingerprinted) <paramref name="url"/>,
+	/// i.e. <c>AddAsset("img.abc123.png", label: "img.png")</c> makes <c>Assets["img.png"]</c> return <c>img.abc123.png</c>.
+	/// </remarks>


LasseHerget

Big thanks @linkdotnet ! I was literally going to look into that this morning! :D
This change should definately resolve #1847.

I just added a few minor suggestions on what I personally would've done differently.
Neither of those suggestions target the logic itself though. That part looks perfect. :)

Let me know if you need another review after applying a suggestion or sth.

Kind regards, and I am really looking forward to this. :D

LasseHerget · 2026-06-06T08:05:55Z

+	/// <param name="label">The label of the asset, used as the lookup key by the <see cref="ResourceAssetCollection"/> indexer. Pass <see langword="null"/> to add the asset without a label.</param>
+	/// <param name="properties">Additional properties to associate with the asset.</param>
+	[SuppressMessage("Design", "CA1054:URI-like parameters should not be strings", Justification = "Using string to align with ResourceAsset")]
+	public void AddAsset(string url, string? label = null, params ResourceAssetProperty[] properties)


Suggestion

Consider using an IEnumerable for the properties to support all enumerations:

public void AddAsset(string url, string? label = null, params IEnumerable<ResourceAssetProperty> properties)

That would require...

Since an IEnumerable does not have a length property, we'd need to initialize the props direct with the items:

var props = new List<ResourceAssetProperty>(properties);

or

var props = properties.ToList();

To avoid duplicate enumeration, we'd have to adjust the check for duplicate label property:

if (props.Any(static property => string.Equals(property.Name, "label", StringComparison.Ordinal)))

We'd have to consolidate the call from the BunitContext.

LasseHerget · 2026-06-06T08:06:34Z

+				throw new ArgumentException("The label must not be empty or whitespace.", nameof(label));
+			}
+
+			if (properties.Any(static property => string.Equals(property.Name, "label", StringComparison.Ordinal)))


Consider declaring a constant for the label property.

LasseHerget · 2026-06-06T08:10:12Z

+				throw new ArgumentException("The label property is reserved when a label is provided.", nameof(properties));
+			}
+
+			props.Add(new ResourceAssetProperty("label", label));


Personal preference

IDE0090: Simplify new expression

Suggested change

props.Add(new ResourceAssetProperty("label", label));

props.Add(new("label", label));

Similar suggestion for line 127.

LasseHerget · 2026-06-06T08:12:04Z

+
+	/// <summary>
+	/// Adds an asset to the <see cref="ResourceAssetCollection"/> that components
+	/// rendered with this <see cref="BunitContext"/> can access through their <c>Assets</c> property.


Consider referencing the assets property instead of just mentioning it:

Suggested change

/// rendered with this <see cref="BunitContext"/> can access through their <c>Assets</c> property.

/// rendered with this <see cref="BunitContext"/> can access through their <see cref="ComponentBase.Assets"/> property.

LasseHerget · 2026-06-06T08:19:09Z

+	/// Adds an asset to the <see cref="ResourceAssetCollection"/> that components
+	/// rendered with this <see cref="BunitContext"/> can access through their <c>Assets</c> property.
+	/// </summary>
+	/// <remarks>


Consider inheriting the documentation (arguments and remarks) from the BunitRenderer, to avoid redundancy:

/// <summary> /// Adds an asset to the <see cref="ResourceAssetCollection"/> that components /// rendered with this <see cref="BunitContext"/> can access through their <see cref="ComponentBase.Assets"/> property. /// </summary> /// <inheritdoc cref="BunitRenderer.AddAsset"/>

linkdotnet requested review from Copilot and egil June 5, 2026 18:09

Copilot started reviewing on behalf of linkdotnet June 5, 2026 18:09 View session

Copilot AI reviewed Jun 5, 2026

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feat: Add Asset handling

a129c9d

linkdotnet force-pushed the feat/#1846 branch from 14d438b to a129c9d Compare June 5, 2026 18:32

LasseHerget reviewed Jun 6, 2026

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	props.Add(new ResourceAssetProperty("label", label));
	props.Add(new("label", label));

	/// rendered with this <see cref="BunitContext"/> can access through their <c>Assets</c> property.
	/// rendered with this <see cref="BunitContext"/> can access through their <see cref="ComponentBase.Assets"/> property.

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Suggestion

That would require...

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