What am I missing about Ruby blocks that the following happens in factory_girl?

factories.rb

FactoryGirl.define do
  factory :user do
    sequence(:username) { |n| "bob-#{n}" }
    email { |u| "#{u.username}@example.com" }
    password 'password123'

    # the following works:
    factory :bob do username 'bob' end

    # but this does not:
    factory :alice { username 'alice' }
    #=> syntax error, unexpected '{', expecting keyword_end
    #    factory :alice { username 'alice' }
    #                    ^
  end
end

factory :alice, {username 'alice'}

you're missing a comma between :alice and {

@derickbailey, I don't think that's it either. If I recall correctly, { ... } and do ... end both define a block in this case, its just a matter of precedence - the do ... end is higher. So my guess is that it's not high enough to correctly be associated with the factory method as it's last arg.

Just to be sure, I tried the following

factory :alice, { username 'alice' }
#=> syntax error, unexpected tSTRING_BEG, expecting keyword_do or '{' or '('
#    factory :alice, { username 'alice' }
#                                ^

... oh, i see... you were trying to use { } as a block, not as a hash. the reason that doesn't work is precedence of {} vs do ... end, like you said.

the precedence of { } is the previous keyword or invocation... in this case, :alice. Since :alice is not a method call, the interpreter thinks { } should be a hash, not a block.

you have two options... use do ... end for your block, or use parenthesis around the factory call: factory(:alice){ username 'alice' }

this works because the parens tells ruby which part is a param to the method call, which then allows it to realize the { } is a block, not a parameter

What happens if you move the password method up? Same thing? Sounds like it is order of operations.

@objo, @derickbailey
Indeed, it is an issue with the precedence and the interpreter thinking my intended block was really a hash, thus the error. I switched to explicit parens.

factory(:bob) { username 'bob' }
factory(:alice) { username 'alice' }

Thanks, all!