Accept 'shopt -s expand_aliases' as a noop.

Add more spec test cases for alias.

core/state.py

@@ -154,6 +154,8 @@ def __init__(self, mem):
    # these.
    self.nullglob = False
    self.failglob = False
    # No-op for bash compatibility.  We always expand aliases.
    self.expand_aliases = False

    #
    # OSH-specific options that are not yet implemented.
@@ -251,7 +253,7 @@ def SetOption(self, opt_name, b):
        new_val = runtime.Str(':'.join(names))
        self.mem.InternalSetGlobal('SHELLOPTS', new_val)

  SHOPT_OPTIONS = ('nullglob', 'failglob')
  SHOPT_OPTIONS = ('nullglob', 'failglob', 'expand_aliases')

  def SetShoptOption(self, opt_name, b):
    """ For shopt -s/-u. """

spec/alias.test.sh

@@ -4,7 +4,7 @@
#
# http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_03_01
#
# Bash is the only one that doesn't support aliases!
# Bash is the only one that doesn't support aliases by default!

#### Basic alias
shopt -s expand_aliases  # bash requires this
@@ -18,6 +18,21 @@ hi
expected failure
## END

#### define and use alias on a single line
shopt -s expand_aliases
alias e=echo; e one  # this is not alias-expanded because we parse lines at once
e two; e three
## STDOUT:
two
three
## END

#### alias can override builtin
shopt -s expand_aliases
alias echo='echo foo'
echo bar
## stdout: foo bar

#### defining multiple aliases, then unalias
shopt -s expand_aliases  # bash requires this
x=x