New spec tests for 'alias' and 'unalias' builtins, and made them pass.

This is mostly about the argument syntax and error status.  The actual
alias expansion still needs work.

core/builtin.py

@@ -973,6 +973,7 @@ def DeclareTypeset(argv, mem, funcs):
        val = mem.GetVar(name)
        if val.tag != value_e.Undef:
          # TODO: Print flags.

          print(name)
        else:
          status = 1
@@ -989,43 +990,48 @@ def DeclareTypeset(argv, mem, funcs):
ALIAS_SPEC = _Register('alias')


# TODO: Test out all the details here
def Alias(argv, aliases):
  if not argv:
    for name, alias_exp in aliases.iteritems():
      # TODO: Print this better
      print('%s %s' % (name, alias_exp))
    for name in sorted(aliases):
      alias_exp = aliases[name]
      # This is somewhat like bash, except we use %r for ''.
      print('alias %s=%r' % (name, alias_exp))
    return 0

  status = 0
  for arg in argv:
    parts = arg.split('=', 1)
    if len(parts) == 1:
    if len(parts) == 1:  # if we get a plain word without, print alias
      name = parts[0]
      alias_exp = aliases.get(name)
      if alias_exp is None:
        print('alias %r is not defined' % name)  # TODO: error?
        util.error('alias %r is not defined', name)  # TODO: error?
        status = 1
      else:
        print('%s %s' % (name, alias_exp))
        print('alias %s=%r' % (name, alias_exp))
    else:
      name, alias_exp = parts
      aliases[name] = alias_exp

  #print(argv)
  #log('AFTER ALIAS %s', aliases)
  return 0
  return status


UNALIAS_SPEC = _Register('unalias')


# TODO: Test out all the details here
def UnAlias(argv, aliases):
  if not argv:
    util.usage('unalias NAME...')
    return 2

  status = 0
  for name in argv:
    try:
      del aliases[name]
    except KeyError:
      print('alias %r is not defined' % name)  # TODO: error?
      util.error('alias %r is not defined', name)
      status = 1
  return status

spec/alias.test.sh

@@ -18,6 +18,89 @@ hi
expected failure
## END

#### defining multiple aliases, then unalias
shopt -s expand_aliases  # bash requires this
x=x
y=y
alias echo-x='echo $x' echo-y='echo $y'
echo status=$?
echo-x X
echo-y Y
unalias echo-x echo-y
echo status=$?
echo-x X || echo undefined
echo-y Y || echo undefined
## STDOUT:
status=0
x X
y Y
status=0
undefined
undefined
## END

#### alias not defined
alias e='echo' nonexistentZ
echo status=$?
## STDOUT:
status=1
## END
## OK mksh STDOUT:
nonexistentZ alias not found
status=1
## END

#### unalias not defined
alias e=echo ll='ls -l'
unalias e nonexistentZ ll
echo status=$?
## STDOUT:
status=1
## END

#### listing given aliases
alias e=echo ll='ls -l'
alias e ll
## STDOUT:
alias e='echo'
alias ll='ls -l'
## END
## OK mksh/zsh STDOUT:
e=echo
ll='ls -l'
## END
## OK dash STDOUT:
e='echo'
ll='ls -l'
## END

#### alias without args lists all aliases
alias ex=exit ll='ls -l'
alias | grep -E 'ex=|ll='  # need to grep because mksh/zsh have builtin aliases
echo status=$?
## STDOUT:
alias ex='exit'
alias ll='ls -l'
status=0
## END
## OK dash STDOUT:
ex='exit'
ll='ls -l'
status=0
## END
## OK mksh/zsh STDOUT:
ex=exit
ll='ls -l'
status=0
## END

#### unalias without args is a usage error
unalias
echo status=$?
## stdout: status=2
## BUG mksh/dash stdout: status=0
## BUG zsh stdout: status=1

#### alias with trailing space causes alias expansion on second word
shopt -s expand_aliases  # bash requires this

@@ -89,23 +172,6 @@ echo-x echo-x
x echo x
## END

#### defining multiple aliases, then unalias
shopt -s expand_aliases  # bash requires this
x=x
y=y
alias echo-x='echo $x' echo-y='echo $y'
echo-x X
echo-y Y
unalias echo-x echo-y
echo-x X || echo undefined
echo-y Y || echo undefined
## STDOUT:
x X
y Y
undefined
undefined
## END


#### Invalid syntax of alias
shopt -s expand_aliases  # bash requires this