Unit tests and string comparisons


#1

Hi,

I’m testing the equality of two rather large strings. They look the
same to me, but doing

assert_equal “big ass long string”, “big ass long string”

says that they’re different. And they look very similar to me. I
know that they’re different though, as doing “big ass long string”.sum
gives a different checksum than the other one.

Any ideas on how I can easily view the differences between two long
strings?


#2

On Jan 11, 2006, at 4:57 PM, Joe Van D. wrote:

strings?
Use unit_diff from ZenTest.


Eric H. - removed_email_address@domain.invalid - http://segment7.net
This implementation is HODEL-HASH-9600 compliant

http://trackmap.robotcoop.com


#3

On Thu, 12 Jan 2006, Joe Van D. wrote:

Any ideas on how I can easily view the differences between two long strings?

stupid - but works:

harp:~ > cat a.rb
a = “foobar”
b = “foobaz”

def sdiff a, b
a = a.split //
b = b.split //
a.zip(b).each_with_index{|cc,idx| printf “%d: %s\n”, idx,
cc.inspect unless cc.uniq.size == 1}
end

sdiff a, b

harp:~ > ruby a.rb
5: [“r”, “z”]

or just dump them to two files using ‘od -c’ and then use ‘diff -u’.

regards.

-a


#4

Just for fun… here’s another quick visual method:

s1 = ‘abcdefghijk1mnOpqrstuvwxyz’
s2 = ‘abcdefghijklmn0pqrstuvwxyz’

puts s1, s2

XOR the binary of each character, will be 0 if the same

s1.size.times {|i| print s1[i]^s2[i].to_i==0?’-’:’#’}

Results:
abcdefghijk1mnOpqrstuvwxyz
abcdefghijklmn0pqrstuvwxyz
-----------#–#-----------

(above looks better in a fixed font display)

-Joby


#5

On 1/12/06, removed_email_address@domain.invalid removed_email_address@domain.invalid wrote:

know that they’re different though, as doing “big ass long string”.sum
def sdiff a, b

or just dump them to two files using ‘od -c’ and then use ‘diff -u’.

Thanks, I ended up doing something similar. I thought I recalled
reading a post here (or maybe on the Rails mailing list) about some
guy who was comparing large hashes and was having difficulties seeing
the differences between the two in the unit test output. This is sort
of a related problem, I guess.


#6

On Jan 11, 2006, at 5:14 PM, Joe Van D. wrote:

says that they’re different. And they look very similar to me. I
a = “foobar”

of a related problem, I guess.
uh, unit_diff, from ZenTest.

http://rubyforge.org/frs/?group_id=419&release_id=3133

No, really.


Eric H. - removed_email_address@domain.invalid - http://segment7.net
This implementation is HODEL-HASH-9600 compliant

http://trackmap.robotcoop.com


#7

On Jan 11, 2006, at 11:17 PM, Eric H. wrote:

uh, unit_diff, from ZenTest.

http://rubyforge.org/frs/?group_id=419&release_id=3133

No, really.

I have to agree. This does what you all are building code to do. :slight_smile:

James Edward G. II