Fix dotnet package remove command when project is not specified

src/Cli/dotnet/Commands/Package/Remove/PackageRemoveCommand.cs

@@ -25,7 +25,7 @@ public PackageRemoveCommand(
         _arguments = parseResult.GetValue(PackageRemoveCommandParser.CmdPackageArgument).ToList().AsReadOnly();
         if (_fileOrDirectory == null)
         {
-            throw new ArgumentNullException(nameof(_fileOrDirectory));
+            _fileOrDirectory = Environment.CurrentDirectory;
         }
         if (_arguments.Count != 1)
         {

test/dotnet.Tests/CommandTests/Package/Remove/GivenDotnetPackageRemove.cs

@@ -0,0 +1,90 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.DotNet.Cli.Utils;
+
+namespace Microsoft.DotNet.Cli.Package.Remove.Tests
+{
+    public class GivenDotnetPackageRemove : SdkTest
+    {
+        public GivenDotnetPackageRemove(ITestOutputHelper log) : base(log)
+        {
+        }
+
+        [Fact]
+        public void WhenPackageIsRemovedWithoutProjectArgument()
+        {
+            var projectDirectory = _testAssetsManager
+                .CopyTestAsset("TestAppSimple")
+                .WithSource().Path;
+
+            var packageName = "Newtonsoft.Json";
+            var add = new DotnetCommand(Log)
+                .WithWorkingDirectory(projectDirectory)
+                .Execute("add", "package", packageName);
+            add.Should().Pass();
+
+            // Test the new 'dotnet package remove' command without specifying project
+            var remove = new DotnetCommand(Log)
+                .WithWorkingDirectory(projectDirectory)
+                .Execute("package", "remove", packageName);
+
+            remove.Should().Pass();
+            remove.StdOut.Should().Contain($"Removing PackageReference for package '{packageName}' from project '{projectDirectory + Path.DirectorySeparatorChar}TestAppSimple.csproj'.");
+            remove.StdErr.Should().BeEmpty();
+        }
+
+        [Fact]
+        public void WhenPackageIsRemovedWithProjectOption()
+        {
+            var projectDirectory = _testAssetsManager
+                .CopyTestAsset("TestAppSimple")
+                .WithSource().Path;
+
+            var packageName = "Newtonsoft.Json";
+            var add = new DotnetCommand(Log)
+                .WithWorkingDirectory(projectDirectory)
+                .Execute("add", "package", packageName);
+            add.Should().Pass();
+
+            // Test the new 'dotnet package remove' command with --project option
+            var remove = new DotnetCommand(Log)
+                .WithWorkingDirectory(projectDirectory)
+                .Execute("package", "remove", packageName, "--project", "TestAppSimple.csproj");
+
+            remove.Should().Pass();
+            remove.StdOut.Should().Contain($"Removing PackageReference for package '{packageName}' from project 'TestAppSimple.csproj'.");
+            remove.StdErr.Should().BeEmpty();
+        }
+
+        [Fact]
+        public void WhenNoPackageIsPassedCommandFails()
+        {
+            var projectDirectory = _testAssetsManager
+                .CopyTestAsset("TestAppSimple")
+                .WithSource()
+                .Path;
+
+            var cmd = new DotnetCommand(Log)
+                .WithWorkingDirectory(projectDirectory)
+                .Execute("package", "remove")
+                .Should()
+                .Fail();
+        }
+
+        [Fact]
+        public void WhenMultiplePackagesArePassedCommandFails()
+        {
+            var projectDirectory = _testAssetsManager
+                .CopyTestAsset("TestAppSimple")
+                .WithSource()
+                .Path;
+
+            var cmd = new DotnetCommand(Log)
+                .WithWorkingDirectory(projectDirectory)
+                .Execute("package", "remove", "package1", "package2")
+                .Should()
+                .Fail();
+        }
+    }
+}