Add TerminalSession helper for managing a tmux session

spec/spec_helper.rb

@@ -1,4 +1,5 @@
 require 'rspec/wait'
+require 'terminal_session'
 
 RSpec.configure do |config|
   config.expect_with :rspec do |expectations|

spec/terminal_session.rb

@@ -0,0 +1,55 @@
+require 'securerandom'
+
+class TerminalSession
+  def initialize(width: 80, height: 24, prompt: '', term: 'xterm-256color')
+    tmux_command("new-session -d -x #{width} -y #{height} 'PS1=#{prompt} TERM=#{term} zsh -f'")
+  end
+
+  def run_command(command)
+    send_string(command)
+    send_keys('enter')
+  end
+
+  def send_string(str)
+    tmux_command("send-keys -t 0 -l '#{str.gsub("'", "\\'")}'")
+  end
+
+  def send_keys(*keys)
+    tmux_command("send-keys -t 0 #{keys.join(' ')}")
+  end
+
+  def content(esc_seqs: false)
+    cmd = 'capture-pane -p -t 0'
+    cmd += ' -e' if esc_seqs
+    tmux_command(cmd).strip
+  end
+
+  def clear
+    send_keys('C-l')
+  end
+
+  def destroy
+    tmux_command('kill-session')
+  end
+
+  def cursor
+    tmux_command("display-message -t 0 -p '\#{cursor_x},\#{cursor_y}'").
+      strip.
+      split(',').
+      map(&:to_i)
+  end
+
+  private
+
+  def socket_name
+    @socket_name ||= SecureRandom.hex(6)
+  end
+
+  def tmux_command(cmd)
+    out = `tmux -u -L #{socket_name} #{cmd}`
+
+    raise('tmux error') unless $?.success?
+
+    out
+  end
+end