dotnet-ado-build-test

What this skill does

# dotnet-ado-build-test

.NET build and test pipeline patterns for Azure DevOps: `DotNetCoreCLI@2` task for build, test, and pack operations, NuGet restore with Azure Artifacts feeds using `NuGetAuthenticate@1`, test result publishing with `PublishTestResults@2` for TRX and JUnit formats, code coverage with `PublishCodeCoverageResults@2` for Cobertura and JaCoCo formats, and multi-TFM matrix strategy across net8.0 and net9.0.

**Version assumptions:** `DotNetCoreCLI@2` task (current). `UseDotNet@2` for SDK installation. `NuGetAuthenticate@1` for Azure Artifacts. `PublishTestResults@2` and `PublishCodeCoverageResults@2` for reporting.

**Scope boundary:** This skill owns .NET build and test pipeline configuration for Azure DevOps. Starter CI templates (basic build/test/pack) are owned by [skill:dotnet-add-ci]. Composable pipeline patterns (templates, multi-stage, triggers) are in [skill:dotnet-ado-patterns]. Testing strategy guidance (what to test, test architecture, quality gates) is owned by [skill:dotnet-testing-strategy]. Benchmark CI workflows are owned by [skill:dotnet-ci-benchmarking].

**Out of scope:** Starter CI templates -- see [skill:dotnet-add-ci]. Test architecture and strategy -- see [skill:dotnet-testing-strategy]. Benchmark regression detection in CI -- see [skill:dotnet-ci-benchmarking]. Publishing and deployment -- see [skill:dotnet-ado-publish] and [skill:dotnet-ado-unique]. GitHub Actions build/test workflows -- see [skill:dotnet-gha-build-test].

Cross-references: [skill:dotnet-add-ci] for starter build/test templates, [skill:dotnet-testing-strategy] for test architecture guidance, [skill:dotnet-ci-benchmarking] for benchmark CI integration.

---

## `DotNetCoreCLI@2` Task

### Build

```yaml
steps:
  - task: UseDotNet@2
    displayName: 'Install .NET SDK'
    inputs:
      packageType: 'sdk'
      version: '8.0.x'

  - task: DotNetCoreCLI@2
    displayName: 'Restore'
    inputs:
      command: 'restore'
      projects: 'MyApp.sln'

  - task: DotNetCoreCLI@2
    displayName: 'Build'
    inputs:
      command: 'build'
      projects: 'MyApp.sln'
      arguments: '-c Release --no-restore'
```

### Test

```yaml
- task: DotNetCoreCLI@2
  displayName: 'Run tests'
  inputs:
    command: 'test'
    projects: '**/*Tests.csproj'
    arguments: >-
      -c Release
      --logger "trx;LogFileName=test-results.trx"
      --results-directory $(Build.ArtifactStagingDirectory)/test-results
```

### Pack

```yaml
- task: DotNetCoreCLI@2
  displayName: 'Pack NuGet packages'
  inputs:
    command: 'pack'
    packagesToPack: 'src/**/*.csproj'
    configuration: 'Release'
    outputDir: '$(Build.ArtifactStagingDirectory)/nupkgs'
    nobuild: true
```

### Custom Command

For commands not directly supported by the task (e.g., `dotnet tool install`):

```yaml
- task: DotNetCoreCLI@2
  displayName: 'Install dotnet tools'
  inputs:
    command: 'custom'
    custom: 'tool'
    arguments: 'restore'
```

### Multi-Version SDK Install

Install multiple SDK versions for multi-TFM builds:

```yaml
- task: UseDotNet@2
  displayName: 'Install .NET 8'
  inputs:
    packageType: 'sdk'
    version: '8.0.x'

- task: UseDotNet@2
  displayName: 'Install .NET 9'
  inputs:
    packageType: 'sdk'
    version: '9.0.x'
```

Each `UseDotNet@2` invocation adds the SDK version to PATH. The last installed version becomes the default, but all versions are available via `--framework` targeting.

---

## NuGet Restore with Azure Artifacts Feeds

### `NuGetAuthenticate@1` for Feed Authentication

```yaml
steps:
  - task: NuGetAuthenticate@1
    displayName: 'Authenticate NuGet feeds'

  - task: DotNetCoreCLI@2
    displayName: 'Restore'
    inputs:
      command: 'restore'
      projects: 'MyApp.sln'
      feedsToUse: 'config'
      nugetConfigPath: 'nuget.config'
```

The `NuGetAuthenticate@1` task configures credentials for all Azure Artifacts feeds referenced in `nuget.config`. No explicit PAT or API key is needed -- the task uses the pipeline's identity.

### Selecting Feeds Directly

For simple setups without a `nuget.config`, select feeds directly in the restore task:

```yaml
- task: DotNetCoreCLI@2
  displayName: 'Restore with Azure Artifacts'
  inputs:
    command: 'restore'
    projects: 'MyApp.sln'
    feedsToUse: 'select'
    vstsFeed: 'MyProject/MyFeed'
    includeNuGetOrg: true
```

### Upstream Sources

Azure Artifacts feeds can proxy nuget.org as an upstream source. When configured, a single feed reference provides access to both private packages and public NuGet packages:

```xml
<!-- nuget.config with Azure Artifacts upstream -->
<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageSources>
    <clear />
    <add key="MyFeed" value="https://pkgs.dev.azure.com/myorg/_packaging/myfeed/nuget/v3/index.json" />
  </packageSources>
</configuration>
```

With upstream sources enabled on the feed, nuget.org packages are cached in the Azure Artifacts feed, providing a single authenticated source for all packages.

### Cross-Organization Feed Access

For feeds in different Azure DevOps organizations, use a service connection:

```yaml
- task: NuGetAuthenticate@1
  displayName: 'Authenticate external feed'
  inputs:
    nuGetServiceConnections: 'ExternalOrgFeedConnection'

- task: DotNetCoreCLI@2
  displayName: 'Restore'
  inputs:
    command: 'restore'
    projects: 'MyApp.sln'
    feedsToUse: 'config'
    nugetConfigPath: 'nuget.config'
```

---

## Test Result Publishing

### `PublishTestResults@2` with TRX Format

```yaml
- task: DotNetCoreCLI@2
  displayName: 'Run tests'
  inputs:
    command: 'test'
    projects: '**/*Tests.csproj'
    arguments: >-
      -c Release
      --logger "trx;LogFileName=results.trx"
      --results-directory $(Common.TestResultsDirectory)
  continueOnError: true

- task: PublishTestResults@2
  displayName: 'Publish test results'
  condition: always()
  inputs:
    testResultsFormat: 'VSTest'
    testResultsFiles: '$(Common.TestResultsDirectory)/**/*.trx'
    mergeTestResults: true
    testRunTitle: '.NET Unit Tests'
```

**Key decisions:**

- `continueOnError: true` on the test task ensures the publish step always runs, even on test failures
- `condition: always()` on the publish task runs regardless of previous step outcome
- `mergeTestResults: true` combines results from multiple test projects into a single test run
- `testRunTitle` provides a descriptive name in the Azure DevOps Test tab

### JUnit Format

Some third-party test frameworks output JUnit XML. Use the `JUnit` format:

```yaml
- task: PublishTestResults@2
  displayName: 'Publish JUnit results'
  condition: always()
  inputs:
    testResultsFormat: 'JUnit'
    testResultsFiles: '**/junit-results.xml'
    mergeTestResults: true
```

### Test Results with Attachments

Attach screenshots or logs to test results for debugging failed tests:

```yaml
- task: DotNetCoreCLI@2
  displayName: 'Run tests with attachments'
  inputs:
    command: 'test'
    projects: '**/*Tests.csproj'
    arguments: >-
      -c Release
      --logger "trx;LogFileName=results.trx"
      --results-directory $(Common.TestResultsDirectory)
      --collect:"XPlat Code Coverage"
  continueOnError: true

- task: PublishTestResults@2
  displayName: 'Publish test results'
  condition: always()
  inputs:
    testResultsFormat: 'VSTest'
    testResultsFiles: '$(Common.TestResultsDirectory)/**/*.trx'
    mergeTestResults: true
    testRunTitle: '.NET Tests'
    publishRunAttachments: true
```

---

## Code Coverage

### `PublishCodeCoverageResults@2` with Cobertura

```yaml
- task: DotNetCoreCLI@2
  displayName: 'Test with coverage'
  inputs:
    command: 'test'
    projects: '**/*Tests.csproj'
    arguments: >-
      -c Release
      --collect:"XPlat Code Coverage"
      --results-directory $(Agent.TempDirectory)/coverage

- task: PublishCodeCoverageResults@2
  displayName: 'Publish code coverage'
  inputs:
    summaryFileLocation: '$(Agent.TempDirectory)/coverage/**/coverage.cobertura.xml'
```

The