fix(root): avoid command name collision when registering extensions

Signed-off-by: Babak K. Shandiz <babakks@github.com>

Co-authored-by: Kynan Ware <bagtoad@github.com>
Co-authored-by: Devraj Mehta <devm33@github.com>

pkg/cmd/root/extension_registration_test.go

@@ -0,0 +1,97 @@
+package root
+
+import (
+	"testing"
+
+	"github.com/cli/cli/v2/internal/browser"
+	"github.com/cli/cli/v2/internal/config"
+	"github.com/cli/cli/v2/internal/gh"
+	"github.com/cli/cli/v2/pkg/cmdutil"
+	"github.com/cli/cli/v2/pkg/extensions"
+	"github.com/cli/cli/v2/pkg/iostreams"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewCmdRoot_ExtensionRegistration(t *testing.T) {
+	tests := []struct {
+		name           string
+		extensions     []string
+		wantRegistered []string
+		wantSkipped    []string
+	}{
+		{
+			name:           "extension conflicts with core command 'copilot'",
+			extensions:     []string{"copilot"},
+			wantSkipped:    []string{"copilot"},
+			wantRegistered: []string{},
+		},
+		{
+			name:           "extension does not conflict with any core command",
+			extensions:     []string{"my-custom-extension"},
+			wantSkipped:    []string{},
+			wantRegistered: []string{"my-custom-extension"},
+		},
+		{
+			name:           "extension that conflicts with a core command's alias",
+			extensions:     []string{"agent"},
+			wantSkipped:    []string{"agent"},
+			wantRegistered: []string{},
+		},
+		{
+			name:           "multiple extensions with some conflicts",
+			extensions:     []string{"pr", "custom-ext", "issue", "another-ext"},
+			wantSkipped:    []string{"pr", "issue"},
+			wantRegistered: []string{"custom-ext", "another-ext"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ios, _, _, _ := iostreams.Test()
+
+			var extMocks []extensions.Extension
+			for _, extName := range tt.extensions {
+				extMocks = append(extMocks, &extensions.ExtensionMock{
+					NameFunc: func() string {
+						return extName
+					},
+				})
+			}
+
+			em := &extensions.ExtensionManagerMock{
+				ListFunc: func() []extensions.Extension {
+					return extMocks
+				},
+			}
+
+			f := &cmdutil.Factory{
+				IOStreams: ios,
+				Config: func() (gh.Config, error) {
+					return config.NewBlankConfig(), nil
+				},
+				Browser:          &browser.Stub{},
+				ExtensionManager: em,
+			}
+
+			cmd, err := NewCmdRoot(f, "", "")
+			require.NoError(t, err)
+
+			// Verify skipped extensions (should find core command registered, not extension)
+			for _, extName := range tt.wantSkipped {
+				foundCmd, _, findErr := cmd.Find([]string{extName})
+				assert.NoError(t, findErr, "command %q should be found", extName)
+				assert.NotNil(t, foundCmd, "command %q should exist", extName)
+				assert.NotEqual(t, "extension", foundCmd.GroupID, "command %q should be core command, not extension", extName)
+			}
+
+			// Verify registered extensions (should find extension command registered)
+			for _, extName := range tt.wantRegistered {
+				foundCmd, _, findErr := cmd.Find([]string{extName})
+				assert.NoError(t, findErr, "extension %q should be found", extName)
+				assert.NotNil(t, foundCmd, "extension %q should exist", extName)
+				assert.Equal(t, "extension", foundCmd.GroupID, "command %q should be extension command", extName)
+			}
+		})
+	}
+}

pkg/cmd/root/root.go

@@ -183,6 +183,13 @@ func NewCmdRoot(f *cmdutil.Factory, version, buildDate string) (*cobra.Command,
 	em := f.ExtensionManager
 	for _, e := range em.List() {
 		extensionCmd := NewCmdExtension(io, em, e, nil)
+		// Don't register an extension command if it would
+		// conflict with a core command.
+		_, _, err := cmd.Find([]string{extensionCmd.Name()})
+		if err == nil {
+			continue
+		}
+
 		cmd.AddCommand(extensionCmd)
 	}