Updates for January 2026 .NET releases

CONTRIBUTING.md

@@ -73,6 +73,12 @@ The [`build-and-test.ps1`](https://github.com/dotnet/dotnet-docker/blob/main/bui
     > ./build-and-test.ps1 -Version 9.0 -OS nanoserver-1809 -Mode Test
     ```
 
+- Build and test images on an arm64 device (e.g. Apple Silicon Mac or Linux ARM64 machine). Note: The architecture argument must be `arm64`, not `arm64v8`.
+
+    ``` console
+    > ./build-and-test.ps1 -Paths '*9.0*noble*' -Architecture arm64
+    ```
+
 ### Editing Dockerfiles
 
 The [Dockerfiles](https://github.com/search?q=repo%3Adotnet%2Fdotnet-docker+path%3Asrc%2F**%2FDockerfile&type=code&ref=advsearch) contained in this repo are generated from a set of [Cottle](https://cottle.readthedocs.io/en/stable/page/01-overview.html) based [templates](https://github.com/dotnet/dotnet-docker/tree/main/eng/dockerfile-templates). A single template generates the set of Dockerfiles that are similar (e.g. all Windows sdk Dockerfiles for a particular .NET version). This ensures consistency across the various Dockerfiles and eases the burden of making changes to the Dockerfiles. Instead of editing the Dockerfiles directly, the templates should be updated and then the Dockerfiles should get regenerated by running the [generate Dockerfiles script](https://github.com/dotnet/dotnet-docker/blob/main/eng/dockerfile-templates/Get-GeneratedDockerfiles.ps1).
@@ -105,6 +111,32 @@ There are several types of [tests](https://github.com/dotnet/dotnet-docker/tree/
 
 When editing Dockerfiles, please ensure the appropriate test changes are also made.
 
+#### Running Tests Without Building Images
+
+If you want to test images that have already been built and published to a registry (e.g. official images from `mcr.microsoft.com`), you can run tests without building first by using the `-PullImages` argument with the `run-tests.ps1` script:
+
+- Run tests against published images without building locally:
+
+    ``` console
+    > ./tests/run-tests.ps1 -PullImages -Paths '*9.0*noble*'
+    ```
+
+#### Running Specific Tests
+
+To run specific tests, use the `-CustomTestFilter` argument with either `run-tests.ps1` or `build-and-test.ps1`. This argument accepts [Xunit test filtering](https://learn.microsoft.com/dotnet/core/testing/selective-unit-tests?pivots=xunit) expressions:
+
+- Run a specific test by name:
+
+    ``` console
+    > ./tests/run-tests.ps1 -Paths '*9.0*noble*' -CustomTestFilter "FullyQualifiedName~VerifyEnvironmentVariables"
+    ```
+
+- Run tests using `build-and-test.ps1` with a custom filter:
+
+    ``` console
+    > ./build-and-test.ps1 -Paths '*9.0*noble*' -Mode Test -CustomTestFilter "FullyQualifiedName~VerifyPackageInstallation"
+    ```
+
 #### Debugging Tests Using VS Code
 
 This repo comes with VS Code Task and Launch Profiles to help you debug tests.

build-and-test.ps1

@@ -22,6 +22,9 @@ param(
     # Categories of tests to run
     [ValidateSet("runtime", "runtime-deps", "aspnet", "sdk", "pre-build", "sample", "monitor", "aspire-dashboard")]
     [string[]]$TestCategories = @("runtime", "runtime-deps", "aspnet", "sdk", "monitor", "aspire-dashboard")
+
+    # Custom test filter expression
+    [string]$CustomTestFilter
 )
 
 [System.Collections.ArrayList]$TestCategories = $TestCategories
@@ -42,7 +45,7 @@ if (($Mode -eq "BuildAndTest" -or $Mode -eq "Test")) {
 
     if ($TestCategories.Contains("pre-build"))
     {
-        & ./tests/run-tests.ps1 -TestCategories "pre-build" -Version "*"
+        & ./tests/run-tests.ps1 -TestCategories "pre-build" -Version "*" -CustomTestFilter $CustomTestFilter
         $TestCategories.Remove("pre-build")
     }
     else
@@ -103,12 +106,14 @@ if ($Mode -eq "BuildAndTest" -or $Mode -eq "Test") {
         & ./tests/run-tests.ps1 `
             -Architecture $Architecture `
             -Paths $Paths `
-            -TestCategories $localTestCategories
+            -TestCategories $localTestCategories `
+            -CustomTestFilter $CustomTestFilter
     } else {
         & ./tests/run-tests.ps1 `
             -Version $TestVersion `
             -OSVersions @($OS) `
             -Architecture $Architecture `
-            -TestCategories @localTestCategories
+            -TestCategories @localTestCategories `
+            -CustomTestFilter $CustomTestFilter
     }
 }