Fix dotnet reference add/remove failing when no --project is specified

[Copilot]

dotnet reference add <path> and dotnet reference remove <path> would fail with Could not find project or directory '' when run from a directory containing a project file, because neither command fell back to the current directory when no --project option was provided.

ReferenceListCommand already had the correct behavior; ReferenceAddCommand and ReferenceRemoveCommand were simply missing the ?? Directory.GetCurrentDirectory() fallback.

Changes

• ReferenceAddCommand / ReferenceRemoveCommand: apply ?? Directory.GetCurrentDirectory() when GetFileOrDirectory() returns null, consistent with ReferenceListCommand
• Tests: add WhenNoProjectIsSpecifiedItUsesCurrentDirectory for both add and remove covering the exact repro from the issue report

cd ClassLib2
dotnet reference add ../ClassLib1/ClassLib1.csproj  # previously failed, now works
dotnet reference remove ../ClassLib1/ClassLib1.csproj  # same fix

Original prompt

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This section details on the original issue you should resolve

<issue_title>dotnet reference add can't find project in current directory</issue_title>
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Describe the bug

When I use dotnet reference add ../ClassLib1/ClassLib1.csproj, I get an error message, even though there's a csproj in the current directory

To Reproduce

dotnet new classlib -n ClassLib1
dotnet new classlib -n ClassLib2
cd ClassLib2
dotnet reference add ../ClassLib1/ClassLib1.csproj

Exceptions (if any)

Could not find project or directory ``.

Further technical details

details of dotnet --info

.NET SDK: Version: 10.0.100 Commit: b0f34d51fc Workload version: 10.0.100-manifests.5fb86115 MSBuild version: 18.0.2+b0f34d51f

Runtime Environment:
OS Name: Windows
OS Version: 10.0.26200
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\10.0.100\

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.0
Architecture: x64
Commit: b0f34d51fc

.NET SDKs installed:
8.0.416 [C:\Program Files\dotnet\sdk]
9.0.308 [C:\Program Files\dotnet\sdk]
10.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
DOTNET_ROLL_FORWARD_TO_PRERELEASE [1]

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

- The IDE (VS / VS Code/ VS4Mac) you're running on, and its version

<agent_instructions>investigate and fix this report</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@zivkan I found that using `--project .` works, and is a little bit faster for me to type than `--project RealName.csproj`. Anyway, the point is that the command doesn't appear to use the current directory when no value is passed. @zivkan FWIW, `dotnet package add` has the same issue.

• Fixes dotnet reference add can't find project in current directory #51897

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[Copilot]

Pull request overview

Fixes dotnet reference add/remove <path> failing when invoked from a directory that already contains a project file and no --project is specified, by aligning add/remove behavior with existing list behavior (fallback to current directory).

Changes:

• Add ?? Directory.GetCurrentDirectory() fallback for dotnet reference add project selection when --project isn’t provided.
• Add the same fallback for dotnet reference remove.
• Add regression tests covering “no --project, project is in current directory” for both add and remove.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/Cli/dotnet/Commands/Reference/Add/ReferenceAddCommand.cs	Falls back to current directory when --project is omitted.
src/Cli/dotnet/Commands/Reference/Remove/ReferenceRemoveCommand.cs	Falls back to current directory when --project is omitted.
test/dotnet.Tests/CommandTests/Reference/Add/GivenDotnetAddReference.cs	Adds regression test for dotnet reference add with no --project.
test/dotnet.Tests/CommandTests/Reference/Remove/GivenDotnetRemoveP2P.cs	Adds regression test for dotnet reference remove with no --project.

[baronfel]

/ba-g netanalyzers macos known issue

[baronfel]

/backport to release/10.0.3xx

[github-actions]

Started backporting to release/10.0.3xx (link to workflow run)