About the Expressiveness of D

[Andrei Alexandrescu]

On 4/3/13 2:53 AM, Jacob Carlborg wrote:
> On 2013-04-03 05:03, Jonathan M Davis wrote:
> I actually prefer to have repetitive unit tests and not using loops to
> make it clear what they actually do. Here's an example from our code
> base, in Ruby:
>
> describe "Swedish" do
> subject { build(:address) { |a| a.country_id = Country::SWEDEN } }
>
> it { should validate_postal_code(12345) }
> it { should validate_postal_code(85412) }
>
> it { should_not validate_postal_code(123) }
> it { should_not validate_postal_code(123456) }
>
> it { should_not validate_postal_code("05412") }
> it { should_not validate_postal_code("fooba") }
> end
>
> describe "Finnish" do
> subject { build(:address) { |a| a.country_id = Country::FINLAND } }
>
> it { should validate_postal_code(12345) }
> it { should validate_postal_code(12354) }
> it { should validate_postal_code(41588) }
>
> it { should validate_postal_code("00123") }
> it { should validate_postal_code("01588") }
> it { should validate_postal_code("00000") }
>
> it { should_not validate_postal_code(1234) }
> it { should_not validate_postal_code(123456) }
> it { should_not validate_postal_code("fooba") }
> end
>
> It could be written less repetitive, like this:
>
> postal_codes = {
> Country::SWEDEN => {
> valid: [12345, 85412],
> invalid: [123, 123456, "05412", "fooba"]
> },
>
> Country::FINLAND => {
> valid: [12345, 12354, 41588],
> invalid: ["00123", "01588", "00000", 1234, 123456, "fooba"]
> }
> }
>
> postal_codes.each do |country_id, postal_codes|
> describe c.english_name do
> subject { build(:address) { |a| a.country_id = country_id } }
>
> postal_codes[:valid].each do |postal_code|
> it { should validate_postal_code(postal_code) }
> end
>
> postal_codes[:invalid].each do |postal_code|
> it { should_not validate_postal_code(postal_code) }
> end
> end
> end
>
> But I don't think that looks any better. I think it's much worse.

The way I see it, the first is terrible and the second asks for better 
focus on a data-driven approach.

Andrei