```ruby
require 'spec_helper'

describe 'bundle executable' do
  it 'returns non-zero exit status when passed unrecognized options' do
    mami '--invalid_argument'
    expect(err).to include('Unknown switches')
  end
end

describe 'common case' do
  it 'returns common output' do
    mami ''
    expect(out).to eq('/path/to/mami/2011-08-28-12-34-56.txt')
  end
end
```

Add MAMI_DIR on before block
user
```ruby
require 'spec_helper'

describe 'bundle executable' do
  it 'returns non-zero exit status when passed unrecognized options' do
    mami '--invalid_argument'
    expect(err).to include('Unknown switches')
  end
end

describe 'common case' do
  before do
    ENV['MAMI_DIR'] = "/path/to/mami"
  end

  it 'returns common output' do
    mami ''
    expect(out).to eq('/path/to/mami/2011-08-28-12-34-56.txt')
  end
end
```
assistant