Invalid parameter order when adding a project to sln using `dotnet sln add` should be validated

General Information

The dotnet sln add should respect the order of parameter passed. If the order of the passed parameters are incorrect or invalid, it should display error and the command should not be executed successfully. Current dotnet sln add executed successfully when invalid order of parameters are passed.

Based on the current help from dotnet sln add -h the parameters are ordered using this syntax: dotnet sln <SLN_FILE> add [options] <PROJECT_PATH> taken from:

D:\samplenet50>dotnet sln add -h
Usage: dotnet sln <SLN_FILE> add [options] <PROJECT_PATH>

Arguments:
  <SLN_FILE>       The solution file to operate on. If not specified, the command will search the current directory for one.
  <PROJECT_PATH>   The paths to the projects to add to the solution.

Options:
  --in-root               Place project in root of the solution, rather than creating a solution folder.
  -s, --solution-folder   The destination solution folder path to add the projects to.
  -h, --help              Show command line help.

SDK versions used

• 3.1 SDK: 3.1.403
• 5.0 SDK: 5.0.103, 5.0202, 5.0.203

Operating system

• Windows 10 1909
• Windows 10 2004
• Ubuntu 20 on WSL

Steps to reproduce

The steps are:

1. Create new sln using dotnet new sln, example: dotnet new sln Solution50
2. Create any kind of new project. For example: dotnet new mstest -n UnitTest01
3. Add the created new project into the previously created sln above, with invalid order of the parameters passed. Example: dotnet sln add Solution50.sln UnitTest01\UnitTest01.csproj

Expected result: The project should not be added and it should display error with meaningful error message.

Actual result: The project added into the solution, but it still display error message.

Invalid project `D:\samplenet50\Solution50.sln`. The project file could not be loaded. Data at the root level is invalid. Line 2, position 1.  D:\samplenet50\Solution50.sln.
Project `UnitTest01\UnitTest01.csproj` added to the solution.

Sample:

[sfoslund]

@eriawan thanks for filing an issue. This does seem to be a problem but I’m going to add it to our backlog as it is lower priority than other issues we have.

[DavidKarlas]

I transferred issue to dotnet/sdk because dotnet sln lives there.