japh(r) by Chris Strom: Small Steps / Mini Calendar

‹prev | My Chain | next›

With half a brain, I was able to drive by example a start on the homepage mini-calendar. I left off with the mini-calendar showing a numeric date and little else. This was all done in the Sinatra action:

get %r{/mini/.*} do
  url = "#{@@db}/_design/meals/_view/count_by_month?group=true\&limit=1\&descending=true"
  data = RestClient.get url
  @last_month = JSON.parse(data)['rows'].first['key']

  "<h1>#{@last_month}</h1>"
end

Although not an MVC framework, I have done my view code separately in Haml templates. So first up today is to write some examples for the mini-calendar view. As can be seen from the mini action, there will be a @last_month (with a meal) instance variable, so my examples will all expect that to be set. In RSpec:

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper' )

describe "mini_calendar.haml" do
  before(:each) do
    assigns[:last_month] = "2009-08"
  end
end

The first example will describe the date heading:

  it "should show a human readable month and year" do
    render("views/mini_calendar.haml")
    response.should have_selector("h1", :content => "August 2009")
  end

Running this example, of course, I find failure due to the lack of the template:

cstrom@jaynestown:~/repos/eee-code$ spec ./spec/views/mini_calendar.haml_spec.rb 
F

1)
Errno::ENOENT in 'mini_calendar.haml should show a human readable month and year'
No such file or directory - ./views/mini_calendar.haml
/home/cstrom/repos/eee-code/spec/spec_helper.rb:25:in `read'
/home/cstrom/repos/eee-code/spec/spec_helper.rb:25:in `render'
./spec/views/mini_calendar.haml_spec.rb:9:

Finished in 0.00705 seconds

1 example, 1 failure

Once again I find myself in the familiar, comfortable confines of the change-the-message or make-it-pass cycle. I can change the above message by creating the template. The new failure message becomes:

cstrom@jaynestown:~/repos/eee-code$ spec ./spec/views/mini_calendar.haml_spec.rb 
F

1)
'mini_calendar.haml should show a human readable month and year' FAILED
expected following output to contain a <h1>August 2009</h1> tag:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">

./spec/views/mini_calendar.haml_spec.rb:10:

Finished in 0.007892 seconds

1 example, 1 failure

Finally, I can make the example pass by displaying the current month inside an <h1> tag:

%h1
  = month_text @last_month

The reason for the change-the-message or make-it-pass cycle is to ensure that every step is built on validated assumptions from the previous step. There is nothing worse than spending 10 minutes trying to solve a problem only to realize that you are solving the wrong problem (like creating the template with the wrong name).

I do notice a problem with my naming convention. The Haml template will always show the month requested, not the "latest month". The current step in the current Cucumber scenario drove a default date—the last month with a meal. But as mentioned, this template is displaying the requested month. So I change the expected instance variable in the examples from @last_month to @month:

describe "mini_calendar.haml" do
  before(:each) do
    assigns[:month] = "2009-08"
  end

  it "should show a human readable month and year" do
    render("views/mini_calendar.haml")
    response.should have_selector("h1", :content => "August 2009")
  end
end

Oddly enough, that example still passes:

cstrom@jaynestown:~/repos/eee-code$ spec ./spec/views/mini_calendar.haml_spec.rb
.

Finished in 0.008105 seconds

1 example, 0 failures

The reason for the non-failure has to do with the month_text helper method:

    def month_text(date_frag)
      Date.parse("#{date_frag}-01").strftime("%B %Y")
    end

Since the @last_month variable is not being set in the example, date_frag argument is now nil. This means that Date.parse is now trying to parse the string "-01". How can that return an actual date? Somehow it does:

>> Date.parse("-01").to_s
=> "2009-08-01"

This example will fail in two days (once the example month is different than the current month). For the time being, I will create another example to fail as expected:

  it "should show a human readable month and year for other months" do
    assigns[:month] = "2009-01"
    render("views/mini_calendar.haml")
    response.should have_selector("h1", :content => "January 2009")
  end

That example does fail:

cstrom@jaynestown:~/repos/eee-code$ spec ./spec/views/mini_calendar.haml_spec.rb 
.F

1)
'mini_calendar.haml should show a human readable month and year for other months' FAILED
expected following output to contain a <h1>January 2009</h1> tag:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html><body><h1>
  August 2009
</h1></body></html>
./spec/views/mini_calendar.haml_spec.rb:16:

Finished in 0.010549 seconds

2 examples, 1 failure

Making that example pass is a simple matter of using the new @month instance variable:

%h1
  = month_text @month

This was a nice demonstration of the value in taking small steps in the change-the-message or make-it-pass cycle. I could have easily made the changes without the small steps. I might even have made the change without introducing a subtle defect. By taking small steps, I know that I have not introduced a subtle defect.

With that, I can work my way back out to the Cucumber scenario to mark the current step as complete:

Then /^I should see the calendar for (.+)$/ do |date|
  response.should have_selector("h1", :content => date)
end

Cucumber had not suggested the RegExp for the date—rather I saw an opportunity for re-use coming very soon. And, indeed, in addition to one newly passing step, I have some blue ones as well:

I spend a little more time driving days in the mini-calendar. Tomorrow I ought to be able to link to meals from the calendar and mark off another step or two in my scenario.

japh(r) by Chris Strom

Sunday, August 30, 2009

Small Steps / Mini Calendar

No comments:

Post a Comment