Fix test for closing ] in [.

Fixes issue #82.

core/test_builtin.py

@@ -119,7 +119,7 @@ def Test(argv, need_right_bracket):
  The only difference between test and [ is that [ needs a matching ].
  """
  if need_right_bracket:
    if argv[-1] != ']':
    if not argv or argv[-1] != ']':
      util.error('[: missing closing ]')
      return 2
    del argv[-1]

doc/osh-quick-ref-toc.txt

@@ -32,6 +32,7 @@ X [Conditional]   switch   match   if-expr (
X [Iteration]     for-expr (   while-expr (
X [Grouping]      proc   func   lazy   pure   do {   shell {  
X [Context]       with-cd   with-redir   with-env   with-vars   with-file
                  with-logger
X [Concurrency]   fork
X [Redirects]     multiline-string '''_"""   file-descriptor !0

@@ -157,6 +158,7 @@ X [xargs]         each

OIL LIBRARIES

X [Builtin Procs] log   die
X [Builtin Funcs] shEvalArith()   shEvalWord()
X [getopts]       ?
X [Testing]       ?

spec/builtin-test.test.sh

@@ -65,16 +65,29 @@ test -n x ]
echo status=$?
test -n x y
echo status=$?
# stdout-json: "status=2\nstatus=2\n"
## STDOUT:
status=2
status=2
## END

### ] syntax errors
[
echo status=$?
test  # not a syntax error
echo status=$?
[ -n x  # missing ]
echo status=$?
[ -n x ] y  # extra arg after ]
echo status=$?
[ -n x y  # extra arg
echo status=$?
# stdout-json: "status=2\nstatus=2\nstatus=2\n"
## STDOUT:
status=2
status=1
status=2
status=2
status=2
## END

### -n
test -n 'a'  && echo true