Product Information:
Version: 2.1.4
Runtime Environment:
OS Name: Mac OS X
OS Version: 10.13
OS Platform: Darwin
RID: osx.10.12-x64
Base Path: /usr/local/share/dotnet/sdk/2.1.4/

Microsoft .NET Core Shared Framework Host

Version : 2.0.5
Build : 17373eb129b3b05aa18ece963f8795d65ef8ea54

CompHostNameHere:DotNetCoreKoans notu$ dotnet watch --quiet run Koans/AboutLinq.cs(41,38): error CS0021: Cannot apply indexing with [] to an expression of type 'IEnumerable<int>' [/Users/notu/code/DotNetCoreKoans/DotNetCoreKoans.csproj] Koans/AboutArrays.cs(41,13): warning xUnit2015: Do not use typeof() expression to check the exception type. [/Users/notu/code/DotNetCoreKoans/DotNetCoreKoans.csproj] Koans/AboutDelegates.cs(135,4): warning xUnit2013: Do not use Assert.Equal() to check for collection size. [/Users/notu/code/DotNetCoreKoans/DotNetCoreKoans.csproj] Koans/AboutFloats.cs(59,13): warning xUnit2015: Do not use typeof() expression to check the exception type. [/Users/notu/code/DotNetCoreKoans/DotNetCoreKoans.csproj] Koans/AboutNull.cs(24,13): warning xUnit2015: Do not use typeof() expression to check the exception type. [/Users/notu/code/DotNetCoreKoans/DotNetCoreKoans.csproj] Koans/AboutGenericContainers.cs(131,4): warning xUnit2015: Do not use typeof() expression to check the exception type. [/Users/notu/code/DotNetCoreKoans/DotNetCoreKoans.csproj] Koans/AboutGenericContainers.cs(219,4): warning xUnit2015: Do not use typeof() expression to check the exception type. [/Users/notu/code/DotNetCoreKoans/DotNetCoreKoans.csproj]

Line 41 is ` Assert.Equal(FILL_ME_IN, lowNums[0]);

Consider ripping it out for an simple assertion library.

To reach the maximum number of people who wish to learn C#, let's implement development container support for this project.

The end goal is a user being able to clone the repository, open it in vscode and have the Visual Studio Code Remote Development extension to provide them a development environment with no local installs.

The ultimate end game is learners can use GitHub Codespaces to learn and have nothing installed on their machine.

It would be awesome to have a logo for the project that can be used in documentation. Something based on the original Ruby Koans swirl logo would be awesome.

The original ruby koans had a great koan about iteration. What would that look like for C#?

When trying to run this on Windows 10, it crashes. (And yes, I've installed, re-installed and re-re-installed .NET Core 1.0)

Console output:

C:\Dev\Git\DotNetCoreKoans>dotnet restore
log  : Restoring packages for C:\Dev\Git\DotNetCoreKoans\project.json...
log  : Restoring packages for tool 'Microsoft.DotNet.Watcher.Tools' in C:\Dev\Git\DotNetCoreKoans\project.json...
log  : Lock file has not changed. Skipping lock file write. Path: C:\Dev\Git\DotNetCoreKoans\project.lock.json
log  : C:\Dev\Git\DotNetCoreKoans\project.json
log  : Restore completed in 2079ms.

C:\Dev\Git\DotNetCoreKoans>dotnet watch run
Unhandled Exception: System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.DotNet.ProjectModel, Version=1.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.
   at Microsoft.DotNet.Watcher.Tools.Program.<>c__DisplayClass3_0.<MainInternal>b__0()
   at Microsoft.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args)
   at Microsoft.DotNet.Watcher.Tools.Program.MainInternal(String[] args, CancellationToken cancellationToken)
   at Microsoft.DotNet.Watcher.Tools.Program.Main(String[] args)

Also noticed some extra blank lines that I'd like to clean up. PR incoming

From a clean clone of the repo, building on VS for Mac (7.2) reports the following packages as downgrades.

• System.Net.Primitives
• Microsoft.DotNet.Cli.Utils
• System.Net.Sockets
• System.Security.Principal

Cleaning Solution: DotNetCoreKoans (Debug)
Build started 16/10/2017 21:49:57.

Project "/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj" (Clean target(s)):

Target ReportAssetsLogMessages:
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: Detected package downgrade: System.Net.Primitives from 4.3.0 to 4.0.11. Reference the package directly from the project to select a different version.
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Net.Sockets (>= 4.1.0) -> runtime.win.System.Net.Sockets (>= 4.3.0) -> System.Net.Primitives (>= 4.3.0)
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Net.Primitives (>= 4.0.11)
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: Detected package downgrade: System.Security.Principal from 4.3.0 to 4.0.1. Reference the package directly from the project to select a different version.
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Net.Sockets (>= 4.1.0) -> runtime.win.System.Net.Sockets (>= 4.3.0) -> System.Security.Principal.Windows (>= 4.3.0) -> System.Security.Principal (>= 4.3.0)
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Security.Principal (>= 4.0.1)
Build continuing because "ContinueOnError" on the task "ReportAssetsLogMessages" is set to "ErrorAndContinue".
Done building target "ReportAssetsLogMessages" in project "DotNetCoreKoans.csproj" -- FAILED.

Done building project "DotNetCoreKoans.csproj" -- FAILED.

Build FAILED.

/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: Detected package downgrade: System.Net.Primitives from 4.3.0 to 4.0.11. Reference the package directly from the project to select a different version.
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Net.Sockets (>= 4.1.0) -> runtime.win.System.Net.Sockets (>= 4.3.0) -> System.Net.Primitives (>= 4.3.0)
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Net.Primitives (>= 4.0.11)
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: Detected package downgrade: System.Security.Principal from 4.3.0 to 4.0.1. Reference the package directly from the project to select a different version.
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Net.Sockets (>= 4.1.0) -> runtime.win.System.Net.Sockets (>= 4.3.0) -> System.Security.Principal.Windows (>= 4.3.0) -> System.Security.Principal (>= 4.3.0)
/Users/richard/Documents/Dev/DotNetCoreKoans/DotNetCoreKoans.csproj : error NU1605: DotNetCoreKoans (>= 2.0.0) -> Microsoft.DotNet.Cli.Utils (>= 2.0.0) -> Microsoft.Build (>= 15.3.409) -> System.IO.Pipes (>= 4.0.0) -> System.Security.Principal (>= 4.0.1)
0 Warning(s)
2 Error(s)

Time Elapsed 00:00:00.31

---------------------- Done ----------------------

Clean: 2 errors, 0 warnings

same value name in different scope.

warning : The tool 'microsoft.dotnet.watcher.tools' is now included in the .NET Core SDK. Information on resolving this warning is available at (https://aka.ms/dotnetclitools-in-box)

This appears twice when initiating dotnet watch on the koans and on each file-save, which makes the experience a bit less pleasant. I have a PR (#60) with a fix, and it appears to work:

Remove the ItemGroup/DotNetCliToolReference for microsoft.dotnet.watcher.tools from the csproj file.

This is the link above for your reference, and what I'm basing my changes on

This koan should be short and to the point.

Things to cover:

• Range
• Performance vs. Percision
• When to use it

Description

After running dotnet migrate on the existing project, it no longer builds. It appears that vstest injects a second static void Main at build time which causes the build to fail. The current project structure will never compile with the current tools.

Possible Solution

• Temporarily create a second project and move the test dependencies to it.
• Completely refactor the application to move tests out of the main project.
• File bugs and wait for a fix.
• Shake fist at sky and demand a resolution from god.

This bug is also submitted to xunit/xunit#1172 and microsoft/vstest#636

Steps to reproduce

1. Clone DotnetCoreKoans
2. Checkout the vs2017 branch git checkout vs2017
3. Perform a dotnet restore
4. Perform a dotnet build

Expected behavior

Console project should successfully build with no errors.

Actual behavior

Engine\Program.cs(8,27,8,31): error CS0017: Program has more than one entry point defined. Compile with /main to specify the type that contains the entry point.

When the project is loaded into codespaces. The output pane becomes active and you can see OmniSharp, .NET Core Debugger and the Razor Language Server being installed.

Note: This is specifically about visual studio code dependencies not the .net project dependencies.

There should be a way to preload these dependencies.

The project readme suggests that .NET Core SDK 2.1 is required, however the project has already been updated to use .NET Core 3.1, this is just to update the readme to keep it in sync.

for example 4 & 4 = ?, 4 | 4 = ?, 4^4 = ?, 4<<2 ? and 4 >>2?

The original ruby koans had a great koan about classes. What would that look like for C#?

To assist new contributors to the codebase, create a code tour for new contributors that walks them through how the application is structured and explains how it works and its goals.

In the Visual Studio Code Editor there is no error message displayed to help the user figure out how to solve the Koan.

So I built this thing and ran it and I'm getting this message in the console:

$ dotnet watch run
[DotNetWatcher] info: Running dotnet with the following arguments: run
[DotNetWatcher] info: dotnet process id: 5428
Project DotNetCoreKoans (.NETCoreApp,Version=v1.0) was previously compiled. Skipping compilation.
AboutAsserts AssertTruth has damaged your karma.
The Master says:
  You have not yet reached enlightenment.
[DotNetWatcher] fail: dotnet exit code: -1
[DotNetWatcher] info: Waiting for a file to change before restarting dotnet...

I did a debug and stepped through the whole thing and it appears as though it's running through several completely empty method blocks and eventually hitting a program exit of -1. So indeed, it was programmed to behave like this. My question is, what exactly is the intended purpose here?

With the release of vs2017 our appveyor build needs to be updated.

• Migrate over to a build like Gringotts

Hello, loved your Koans. I did notice a few minor issues that I'd be happy to correct for you if you'd like. Thanks for making this project.

Javascript is best!

It would be nice to add a step about string interpolation.
Something like
var firstName = "Matt"; var lastName = "Groves"; var str = $"My name is {firstName} {lastName}";
May I do a PR please?

This koan could demostrate basic LINQ functionality.

Things to cover:

• Where

• OrderBy

• Take

• Any

The original ruby koans had a great koan about constants. What would that look like for C#?

Because this koan project is built for .NET Core we can assume C# 6 features. Update the AboutStrings koan to include new features.

Really useful project!

In AboutStrings there's an issue with BuiltInDateFormaters and CustomDateFormaters for those of us outside the USA in that the date format is invalid. Changing to explicitly use the Invariant Culture resolves things.

DateTime.Parse("12/16/2011 2:35:02 PM", CultureInfo.InvariantCulture)

Perhaps a globalization koan might be worth adding ;)

When the project is opened in codespaces, the outline and timeline panels are displayed.

In order to keep the UI noise free for learners, find a way to disable these panels.

Once we have a logo, we should create or locate a custom theme for the devcontainer that matches the logo's color scheme.

It's just named "f" now, but what about something like "IteratingOverDictionary" or "AddingDataViaSubscript" or "DictionaryManipulation"?

The original ruby koans had a great koan about true and false. What would that look like for C#?

When running the koans with the dotnet watch run command, the color coded console output is stripped.

Reported to aspnet/DotNetTools#14

Looks to be resolved with dotnet/cli#1977

What is the relevancy of this koan?

[Step(1)]
public void NullIsNotAnObject()
{
    Assert.True(typeof(object).IsAssignableFrom(null)); //not everything is an object
}

The parameter of IsAssignableFrom is of type Type, and it is documented that it returns false if the parameter is null. So this looks like an implementation detail of this function and not something generally true about objects or null. Am I missing something?

The AboutLambdas portion of the project is dependent on some knowledge of delegates and even comments "[t]he AboutDelegates Koans introduced you to delegates". However, the program checks for all changes to AboutLambdas before AboutDelegates.

Currently it is pretty janky. Maybe push reporting into the Koan base class and allow each koan to report their state to an interface.

The original ruby koans had a great koan about exceptions. What would that look like for C#?

There is a mistaqke in the numbering of strings. Step 22 is duplicate.
May I fix this?

Assert in VerbatimStringsCanHandleMultipleLinesToo considers
var literalString = @"I\r\nam a\r\nbroken line";
to be different from verbatimString, throws error:

There was an error, Xunit.Sdk.EqualException: Assert.Equal() Failure                                                           
           Γåô (pos 1)                                                                                                         
Expected: I\r\nam a\r\nbroken line                                                                                             
Actual:   I\r\nam a\r\nbroken line                                                                                             
           Γåæ (pos 1)  

Strings are tricky beasts. When showing messages to users it appears easy on the surface. But what about your Spanish speaking users? Japanese? This koan should demonstrate how globalization works in .net.

Add a koan called AboutIntegers that walks a new learner through the intricate details about int and uint.

There are malformed links in the readme.md file. Fix them up.

When running the koans using the dotnet-watch, watch spams the output with messages. I Filed a bug on the watch library.

aspnet/DotNetTools#142

Hi,

I'm giving these Koans a go and noticed a discrepancy. I'm running the koans on Windows 10.

My solution to VerbatimStringsCanHandleMultipleLinesToo:

    [Step(6)]
    public void VerbatimStringsCanHandleMultipleLinesToo()
    {
      //Tip: What you create for the literal string will have to 
      //escape the newline characters. For Windows, that would be
      // \r\n. If you are on non-Windows, that would just be \n.
      //We'll show a different way next.
      var verbatimString = @"I
am a
broken line";

      // Make sure to use a literal string.
      // Escaped characters in verbatim strings are covered later.
      var literalString = "I\nam a\nbroken line";
      Assert.Equal(18, verbatimString.Length);
      Assert.Equal(literalString, verbatimString);
    }

In the Tip: bit, it says Windows line breaks are \r\n, and \n otherwise. But I'm running Windows, and I had to just use \n to solve the koan. Not sure if the fix here is to change the Tip: or something else.

Get build in a good state before starting refactoring work.

The koans on Delegates and Lambdas are currently disabled because they depend on these two methods which were removed from Array. It looks like the next release adds them back in.

For showing the difference between passing reference types vs. value types

• int
• string
• custom reference type
• custom value type

Docs on Single.Parse here:

OverflowException

.NET Framework and .NET Core 2.2 and earlier versions only: s represents a number less than MinValue or greater than MaxValue.

This koan should be short and to the point.

Things to cover:

• Range
• Floating point weirdness
• When to use it