Convert a .NET 4.x project to .NET Core

Steps to convert .csproj to new VS 2017 format (.NET 4.5 to .NET Core)

delete any files inside the project folder but not included in the project
unload project from visual studio
edit .csproj
a .csproj template with nuget packages, nuget info, code analysis, style cop:

<Project Sdk="Microsoft.NET.Sdk">
	<PropertyGroup>
		<TargetFrameworks>net45;netstandard2.0</TargetFrameworks>
		<RootNamespace>TODO</RootNamespace>
		<Authors>TODO</Authors>
		<Company>TODO</Company>
		<Description>TODO</Description>
		<Copyright>TODO</Copyright>
		<PackageTags>TODO</PackageTags>
		<IncludeSymbols>True</IncludeSymbols>
		<IncludeSource>True</IncludeSource>
		<PackageProjectUrl>TODO</PackageProjectUrl>
		<PackageLicenseUrl>TODO</PackageLicenseUrl>
		<RepositoryUrl>TODO</RepositoryUrl>
		<RepositoryType>git</RepositoryType>
		<Version>0.0.1</Version>
		<CodeAnalysisRuleSet>..\main.ruleset</CodeAnalysisRuleSet>
	</PropertyGroup>
	<ItemGroup>
		<AdditionalFiles Include="..\stylecop.json" Link="stylecop.json" />
	</ItemGroup>
	<ItemGroup>
		<PackageReference Include="SOME.NUGET.PACKAGE" Version="1.0.0" />
		<PackageReference Include="ConfigureAwaitChecker.Analyzer" Version="1.0.1">
			<PrivateAssets>All</PrivateAssets>
		</PackageReference>
		<PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="2.6.0">
			<PrivateAssets>All</PrivateAssets>
		</PackageReference>
		<PackageReference Include="StyleCop.Analyzers" Version="1.1.0-beta006">
			<PrivateAssets>All</PrivateAssets>
		</PackageReference>
	</ItemGroup>
	<ItemGroup>
	  <ProjectReference Include="..\ANOTHER.PROJECT\ANOTHER.PROJECT.csproj" />
	</ItemGroup>
</Project>

Here a csproj for unit tests (nunit)

<Project Sdk="Microsoft.NET.Sdk">

	<PropertyGroup>
		<TargetFrameworks>net45;netstandard2.0</TargetFrameworks>
		
		<IsPackable>false</IsPackable>
	</PropertyGroup>

	<ItemGroup>
		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.0" />
		<PackageReference Include="Moq" Version="4.8.2" />
		<PackageReference Include="NUnit" Version="3.10.1" />
		<PackageReference Include="NUnit3TestAdapter" Version="3.10.0" />
	</ItemGroup>

	<ItemGroup>
	  <ProjectReference Include="..\..\src\YOUR_PROJECT\YOUR_PROJECT.csproj" />
	</ItemGroup>

  <ItemGroup>
    <DotNetCliToolReference Include="Microsoft.DotNet.Watcher.Tools" Version="2.0.0" />
  </ItemGroup>
</Project>

Carefully choose the right target framework. See .NET Standard and Target frameworks.

To compile the solution you can run:

dotnet build -c Release

Inside Visual Studio Code use /property:GenerateFullPaths=true to generate absolute file path and allow $msCompile problemMatcher to work.

To create nuget packages:

dotnet pack -c Release /p:Version=7.7.7

To exclude a csproj from package generator add the property:

<IsPackable>false</IsPackable>

To run unit tests:

dotnet test -c Release

Add --logger:trx to generate test results.

Unfortunately this give a warning for each project that doesn't container tests. See microsoft/vstest#705

A workaround is to write:

dotnet test ./tests/Your.Project.UnitTests/Your.Project.UnitTests.csproj -c Release

or run all tests projects with

Get-ChildItem ".\tests\" -recurse | where {$_.extension -eq ".csproj"} | % { dotnet test "`""$_.FullName"`"" -c Release --logger:trx}

VSTS Tasks

On VSTS use these commands:

Run tests

Get-ChildItem "$env:BUILD_REPOSITORY_LOCALPATH\tests" -recurse | where {$_.extension -eq ".csproj"} | % { dotnet test """$_.FullName""" -c Release --logger:trx}
Create packages

dotnet pack $(build.sourcesdirectory)/*.sln /p:Version=$(GitVersion.NuGetVersionV2) -c Release --output $(build.artifactstagingdirectory)/nuget-packages
Some feed (like the one hosted on VSTS) doesn't support to publish .nupkg and .symbols.nupkg, it will conflict the second push. A solution is to set the variable "NuGet.UseLegacyFindFiles=true" and then use a pattern like $(Build.ArtifactStagingDirectory)/*.nupkg;-:$(Build.ArtifactStagingDirectory)/*.symbols.nupkg See https://stackoverflow.com/a/45209008/209727 .

Code analyzers (code linter)

I have choosen to use Microsoft.CodeAnalysis.FxCopAnalyzers + StyleCop.Analyzers. To enable it just add it as a nuget dependency, but remeber to set <PrivateAssets>All</PrivateAssets> to not include it in the dependencies. See also

To disable rules see main.ruleset (for both stylecop and fxcop), to configure stylecop rules see stylecop.json.

For each project you should add these configuration inside .csproj:

<PropertyGroup>
<CodeAnalysisRuleSet>..\main.ruleset</CodeAnalysisRuleSet>
</PropertyGroup>

Add a nuget package

cd YOUR_PROJECT
dotnet add package PACKAGENAME

Test watch mode

Add the following tools inside the .csproj of the project where you want to run tests

Exec

cd YOUR_TEST_PROJECT
dotnet restore

Execute tests in watch mode

cd YOUR_TEST_PROJECT
dotnet watch test

Execute a console application (old .exe projects)

dotnet yourproject.dll

Visual Studio Code

If using Visual Studio Code the C# extension is raccomanded and after packages restore a restart of the IDE is required.

You can use the following tasks.json to correctly build the solution:

{
		"version": "2.0.0",
		"tasks": [
				{
						"label": "build",
						"command": "dotnet",
						"type": "process",
						"group": {
								"kind": "build",
								"isDefault": true
						},
						"args": [
								"build",
								"${workspaceFolder}",
								"--no-incremental",
								"/property:GenerateFullPaths=true"
						],
						"problemMatcher": "$msCompile"
				}
		]
}