row_is_cut_in_the_middle_solution.rb

# gem "prawn", "0.8.4"
# Sometime there is no enough space for the last table row when it reaches the end of page

Prawn::Document.generate("text_group_overflow_question.pdf") do |pdf|
  add_page_break_if_overflow(pdf) do |pdf|
    # generating table here
    # ...
  end
end

def add_page_break_if_overflow(pdf, &block)
  current_page = pdf.page_count
  roll = pdf.transaction do
    yield(pdf)
  
    pdf.rollback if pdf.page_count > current_page
  end
  
  if roll == false
    pdf.start_new_page
    yield(pdf)
  end
end

text_group_overflow_problem.rb

# gem "prawn", "0.11.1.pre"

Prawn::Document.generate("text_group_overflow_question.pdf") do
  10.times do
    text "I am part of a paragraph"
  end
end

text_group_overflow_solution.rb

# gem "prawn", "0.11.1.pre"

Prawn::Document.generate("text_group_overflow_question.pdf") do
  group do
    10.times do
      text "I am part of a paragraph"
    end
  end
end