chore: Add (skipped) ptytest test that hangs on Intel Mac (and Windows)

pty/ptytest/ptytest_test.go

@@ -1,8 +1,14 @@
 package ptytest_test
 
 import (
+	"fmt"
+	"runtime"
+	"strings"
 	"testing"
 
+	"github.com/spf13/cobra"
+	"github.com/stretchr/testify/require"
+
 	"github.com/coder/coder/pty/ptytest"
 )
 
@@ -15,4 +21,41 @@ func TestPtytest(t *testing.T) {
 		pty.ExpectMatch("write")
 		pty.WriteLine("read")
 	})
+
+	t.Run("Cobra ptytest should not hang when output is not consumed", func(t *testing.T) {
+		t.Parallel()
+
+		tests := []struct {
+			name          string
+			output        string
+			isPlatformBug bool // See https://github.com/coder/coder/issues/2122 for more info.
+		}{
+			{name: "1024 is safe (does not exceed macOS buffer)", output: strings.Repeat(".", 1024)},
+			{name: "1025 exceeds macOS buffer (must not hang)", output: strings.Repeat(".", 1025), isPlatformBug: true},
+			{name: "10241 large output", output: strings.Repeat(".", 10241), isPlatformBug: true}, // 1024 * 10 + 1
+		}
+		for _, tt := range tests {
+			tt := tt
+			// nolint:paralleltest // Avoid parallel test to more easily identify the issue.
+			t.Run(tt.name, func(t *testing.T) {
+				if tt.isPlatformBug && (runtime.GOOS == "darwin" || runtime.GOOS == "windows") {
+					t.Skip("This test hangs on macOS and Windows, see https://github.com/coder/coder/issues/2122")
+				}
+
+				cmd := cobra.Command{
+					Use: "test",
+					RunE: func(cmd *cobra.Command, args []string) error {
+						fmt.Fprint(cmd.OutOrStdout(), tt.output)
+						return nil
+					},
+				}
+
+				pty := ptytest.New(t)
+				cmd.SetIn(pty.Input())
+				cmd.SetOut(pty.Output())
+				err := cmd.Execute()
+				require.NoError(t, err)
+			})
+		}
+	})
 }