.NET cheat sheet

A scannable .NET reference: 16 short snippets across 7 topics, each linking back to the lesson it came from.

At a glance

Quick snippets

.NET SDK and project files

SDK versus runtime

dotnet --list-sdks
# 8.0.404 [C:/Program Files/dotnet/sdk]
# 9.0.100 [C:/Program Files/dotnet/sdk]

dotnet --list-runtimes
# Microsoft.AspNetCore.App 8.0.11 [C:/Program Files/dotnet/shared/Microsoft.AspNetCore.App]
# Microsoft.NETCore.App 8.0.11 [C:/Program Files/dotnet/shared/Microsoft.NETCore.App]

Pinning the SDK version

{
  "sdk": {
    "version": "8.0.404",
    "rollForward": "latestFeature"
  }
}

Full lesson: .NET SDK and project files →

The dotnet CLI workflow

Scaffolding a solution

dotnet new sln -n Shop

dotnet new classlib -n Shop.Core  -o src/Shop.Core
dotnet new webapi   -n Shop.Api   -o src/Shop.Api -f net8.0
dotnet new xunit    -n Shop.Tests -o tests/Shop.Tests

dotnet sln add src/Shop.Core src/Shop.Api tests/Shop.Tests
dotnet add src/Shop.Api reference src/Shop.Core
dotnet add tests/Shop.Tests reference src/Shop.Core

Packages, restore and lock files

dotnet add src/Shop.Api package Microsoft.EntityFrameworkCore.Sqlite
dotnet add src/Shop.Api package Microsoft.EntityFrameworkCore.Sqlite --version 8.0.11
dotnet remove src/Shop.Api package Newtonsoft.Json

dotnet list package                    # direct dependencies
dotnet list package --outdated         # newer versions available
dotnet list package --vulnerable       # known CVEs in the graph
dotnet restore                         # download everything up front

The inner loop

dotnet build                       # Debug
dotnet build -c Release            # optimised, warnings still checked
dotnet build --no-restore          # skip restore when nothing changed
dotnet run --project src/Shop.Api
dotnet run --project src/Shop.Api -- --port 5001   # args after -- reach the app

dotnet test                        # discover and run every test project
dotnet test --filter "FullyQualifiedName~Cart"     # narrow to one class

dotnet watch run --project src/Shop.Api            # hot reload on file save
dotnet format                      # apply the repo .editorconfig rules

Full lesson: The dotnet CLI workflow →

Publishing and deployment

Choosing a publish mode

# framework-dependent: the default production choice
dotnet publish src/Shop.Api -c Release -o out

# self-contained for a host you do not control
dotnet publish src/Shop.Api -c Release -r linux-x64 --self-contained true -o out

# container image that runs on the runtime-only base image
dotnet publish src/Shop.Api -c Release -r linux-x64 --self-contained false -o out

Trimming and native AOT

<PropertyGroup>
  <PublishTrimmed>true</PublishTrimmed>
  <TrimMode>partial</TrimMode>
  <PublishAot>true</PublishAot>
  <InvariantGlobalization>true</InvariantGlobalization>
  <StackTraceSupport>false</StackTraceSupport>
</PropertyGroup>

Trimming and native AOT

// reflection-based serialisation is the classic AOT casualty
// prefer a source-generated context
[JsonSerializable(typeof(Order))]
[JsonSerializable(typeof(List<Order>))]
internal partial class ShopJsonContext : JsonSerializerContext
{
}

// register it once
builder.Services.ConfigureHttpJsonOptions(o =>
    o.SerializerOptions.TypeInfoResolverChain.Insert(0, ShopJsonContext.Default));

Full lesson: Publishing and deployment →

What .NET is: runtime, libraries and support policy

The parts of the platform

# What is installed, and which runtimes a machine actually has
dotnet --version
dotnet --list-sdks
dotnet --list-runtimes

# The same information, machine readable, for a build script
dotnet --info --json | head -40

# What a published application was actually built against
dotnet myapp.dll --info 2>/dev/null || true

LTS, STS and picking a target

<!-- Pin the runtime band a machine may use -->
<PropertyGroup>
  <TargetFramework>net8.0</TargetFramework>
  <RollForward>LatestMinor</RollForward>
</PropertyGroup>

LTS, STS and picking a target

{
  "sdk": { "version": "8.0.400", "rollForward": "latestFeature" }
}

Full lesson: What .NET is: runtime, libraries and support policy →

NuGet and dependency management

Versioning and how resolution works

# See what was actually resolved, including transitives
dotnet list package --include-transitive

# See what a package is pulling in and why
dotnet nuget why MyApp.csproj Microsoft.Extensions.Logging

# Disable a floating version before it surprises you
dotnet list package --outdated --include-transitive

# Vulnerability audit, which is also part of restore in recent SDKs
dotnet list package --vulnerable --include-transitive

Central package management

<!-- In each project file, no Version attribute: one place to change it -->
<ItemGroup>
  <PackageReference Include="Microsoft.Extensions.Hosting" />
  <PackageReference Include="xunit" />
</ItemGroup>

Central package management

# The lock file pins the full graph; commit it and restore from it in CI
dotnet restore --locked-mode

# After an intentional upgrade, regenerate the lock files
dotnet restore --force-evaluate
git add "**/packages.lock.json"

Full lesson: NuGet and dependency management →

Testing .NET code

Mock the boundary, not your own code

# Run everything
dotnet test

# Run one class while iterating
dotnet test --filter FullyQualifiedName~PaymentServiceTests

# Run by trait, which is how you split fast from slow in CI
dotnet test --filter Category=Unit

# With coverage, for a report rather than a gate
dotnet test --collect:"XPlat Code Coverage" --results-directory ./TestResults

Full lesson: Testing .NET code →

Writing and publishing NuGet libraries

Packing, validating and releasing

# Validate a package automatically on every pull request
- name: Pack and check
  run: |
    dotnet pack -c Release -o ./artifacts
    # A package without a readme or with a placeholder version is a defect
    dotnet tool run dotnet-validate --package ./artifacts/*.nupkg

Full lesson: Writing and publishing NuGet libraries →

FAQ

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Last refreshed 2026-09-27.