What part of "return false if there are not exactly 10 characters left after discarding dashes" fails to handle the empty string? A test case for the empty string is is only valuable if the empty string is NOT a special case.
On Wed, 2 Sep 2020 at 22:52, Roelof Wobben <r.wob...@home.nl> wrote: > Op 2-9-2020 om 12:38 schreef Richard O'Keefe: > > There is simply no point in "taking the first nine numbers out". > And there shouldn't BE a test for the string being empty, anywhere. > '' '-' '---' and so on should all be handled the same way. > > Oh well, what stops you doing > > digits := aString select: [:each | each ~= $-]. > digits size = 10 ifFalse: [^false]. > lastDigit := digits la ost. > digits := digits copyFrom: 1 to: 9. > ( (lastDigit = $X or: [lastDigit isDigit]) and: [ > digits allSatisfy: #isDigit] > ) ifFalse: [^false]. > > Now my code does not do this, but it is just 16 lines of code with > nothing that it would make sense to extract. > > > > Nothing only that I could not think of this one for myself. > If I do it the TDD way I come more on the way Im currently thinking > > but does this case then be covered > > test14_EmptyIsbn > | result | > result := isbnVerifierCalculator isValidIsbn: ''. > self assert: result equals: false > > and still I have to do the calcualation to see if it's valid. > If I understand the code well I can use the digits variable ? > > > Roelof > > >
