[rspec-users] fluent chaining drying

Gustavo Delfino
Thu, 26 May 2011 03:30:27 -0000

Thank you Justin & David.

I was able to to use Justin solution. I also tried hard to understand and use
David''s solution but I could not.

Now I am just curious. What is &HaveXXXHelpers.on_column? A reference to a
class method?

Regards,

Gustavo Delfino

On May 25, 2011, at 2:04 PM, Justin Ko wrote:

>
>
> On Wed, May 25, 2011 at 11:20 AM, David Chelimsky <dchelimsky at
gmail.com> wrote:
> On May 25, 2011, at 10:07 AM, Gustavo Delfino wrote:
>
> > Hello all. Thanks to subjects, custom matchers and fluent chaining I
was able to greatly simplify my spec. But now I want to DRY my custom matchers.
> >
> > I have two custom matchers: ''have_text'' and
''have_number'' and both contain exactly the same chains
''on_column'' and ''on_columns''.
> >
> > Is there a way to DRY this up?
> >
> >
> > module CustomColumnsMatchers
> >
> >  RSpec::Matchers.define(:have_text) do |expected_string|
> >    chain(:on_column) do |colnumber|
> >      @index = colnumber - 1
> >      @width = 1
> >    end
> >    chain(:on_columns) do |range|
> >      a = range.to_a
> >      @index = Range.new( a[0]-1, a[-1]-1 )
> >      @width = a[-1] - a[0] + 1
> >    end
> >    match do |line|
> >      line[@index] == expected_string.ljust(@width)
> >    end
> >  end
> >
> >  RSpec::Matchers.define(:have_number) do |expected_number_string|
> >    chain(:on_column) do |colnumber|
> >      @index = colnumber - 1
> >      @width = 1
> >    end
> >    chain(:on_columns) do |range|
> >      a = range.to_a
> >      @index = Range.new( a[0]-1, a[-1]-1 )
> >      @width = a[-1] - a[0] + 1
> >    end
> >    match do |line|
> >      line[@index] ==
expected_number_string.rjust(@width,''0'')
> >    end
> >  end
> >
> > end
> >
> >
> > Regards,
> >
> > Gustavo Delfino
>
> I''d probably do something like:
>
>  RSpec::Matchers.define(:have_text) do |expected_string|
>   chain(:on_column, &HaveXXXHelpers.on_column)
>   chain(:on_columns, &HaveXXXHelpers.on_columns)
>   match do |line|
>     line[@index] == expected_string.ljust(@width)
>   end
>  end
>
> HTH,
> David
> _______________________________________________
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>
> Ahh David beat me to the lambda approach! Here is another way:
>
>
> module CustomColumnsMatchers
>
>  RSpec::Matchers.define(:have_text) do |expected_string|
>    extend ChainMethods
>
>    match do |line|
>      line[@index] == expected_string.ljust(@width)
>    end
>  end
>
>  RSpec::Matchers.define(:have_number) do |expected_number_string|
>    extend ChainMethods
>
>    match do |line|
>      line[@index] ==
expected_number_string.rjust(@width,''0'')
>    end
>  end
>
>  module ChainMethods
>    def self.extended(matcher)
>      matcher.instance_eval do