Bug fix: ignore trailing IFS whitespace chars as well.

Modified spec tests and unit tests to cover this case.

Addresses issue #61.  Alpine invokves 'scanelf', which apparently
outputs trailing spaces that tickled this bug.

core/builtin_test.py

@@ -21,16 +21,23 @@ def testEchoLexer(self):
  def testAppendParts(self):
    # allow_escape is True by default, but False when the user passes -r.
    CASES =  [
        (['Aa', 'b', ' a b'], 'Aa b \\ a\\ b'),
        (['Aa', 'b', ' a b'], 100, 'Aa b \\ a\\ b'),
        (['a', 'b', 'c'], 3, 'a b c '),
    ]

    for expected_parts, line in CASES:
    for expected_parts, max_results, line in CASES:
      sp = legacy.IfsSplitter(legacy.DEFAULT_IFS, '')
      spans = sp.Split(line, True)
      print('--- %r' % line)
      for span in spans:
        print('  %s %s' % span)

      parts = []
      builtin._AppendParts(line, spans, 100, False, parts)
      builtin._AppendParts(line, spans, max_results, False, parts)
      self.assertEqual(expected_parts, parts)

      print('---')


if __name__ == '__main__':
  unittest.main()

core/legacy.py

@@ -323,6 +323,11 @@ def Split(self, s, allow_escape):
    if i == n:
      return spans

    # Ignore trailing IFS whitespace too.  This is necessary for the case:
    # IFS=':' ; read x y z <<< 'a : b : c :'.  We don't want
    while s[n-1] in self.ifs_whitespace:
      n -= 1

    state = ST_START
    while i < n:
      c = s[i]

spec/builtin-io.test.sh

@@ -227,11 +227,12 @@ echo -n ZZZ | { read x; echo $?; echo $x; }
### Read builtin with multiple variables
# NOTE: there are TABS below
read x y z <<EOF
A		B C D E
A		B C D E 
FG
EOF
echo "$x/$y/$z"
# stdout: A/B/C D E
echo "[$x/$y/$z]"
# stdout: [A/B/C D E]
# BUG dash stdout: [A/B/C D E ]
# status: 0

### Read builtin with not enough variables