```ruby
require 'rails_helper'

describe DataSet do

  describe '#process' do

    context 'when all required sheets and headers are present' do

      context 'when columns match data format correctly' do
      end
      
      context 'when columns mismatch data format' do
      end

    end

    context 'when required sheets are missing' do
    end

    context 'when required columns are missing' do
    end

  end
  
end```

Add paths to sample data for testing
user
```ruby
require 'rails_helper'

describe DataSet do

  describe '#process' do

    context 'when all required sheets and headers are present' do

      context 'when columns match data format correctly' do

        well_formatted_excel_path = "./SampleData/SampleData.xlsx"

      end
      
      context 'when columns mismatch data format' do

        format_mismatch_excel_path = "./SampleData/SampleData_formats_wrong.xlsx"

      end

    end

    context 'when required sheets are missing' do
      
      missing_sheet_excel_path = "./SampleData/SampleData_sheets_missing.xlsx"
    
    end

    context 'when required columns are missing' do

      missing_columns_excel_path = "./SampleData/SampleData_columns_missing.xlsx"

    end

  end
  
end```
assistant