Rails - Nov 2010 - Question re assert_equal

In Agile Web Development with Rails, the following statement is given:

assert_equal "has already been taken",
product.errors[:title].join('';
'')

My question is: Why is the join(...) needed and what exactly does it
do here?

If it does what I assume, join an array of strings and use "; " as the
separator, then I wonder how the assert_equal statement could ever
evaluate to true as the first parameter is a static string without ";
"

Can you shed some light for me?

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On Nov 14, 9:48 pm, 24z <r...-3vQWZ2fCnPIwofDVIiI1Aw@public.gmane.org>
wrote:
> In Agile Web Development with Rails, the following statement is given:
>
> assert_equal "has already been taken",
product.errors[:title].join('';
> '')
>
> My question is: Why is the join(...) needed and what exactly does it
> do here?
>
> If it does what I assume, join an array of strings and use "; "
as the
> separator, then I wonder how the assert_equal statement could ever
> evaluate to true as the first parameter is a static string without ";
> "
>
> Can you shed some light for me?
If there is only supposed to be one error on title  (ie the
errors[:title] contains a single string) then join will just return
that string. Hard to say without knowing the wider context, but this
seems a fairly succinct way of saying that there should only be one
error for the title attribute and that it should be the one that comes
from the uniqueness validation.

Fred

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24z wrote in post #961471:
> In Agile Web Development with Rails, the following statement is given:
>
> assert_equal "has already been taken",
product.errors[:title].join('';
> '')
>
> My question is: Why is the join(...) needed and what exactly does it
> do here?
>
> If it does what I assume, join an array of strings and use "; "
as the
> separator, then I wonder how the assert_equal statement could ever
> evaluate to true as the first parameter is a static string without ";
> "
>
That seems like a strangely written assertion.  Obviously, the only way 
it could return true is if product.errors[:title] has only one element.
> Can you shed some light for me?
Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org

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