....('\n---', '${array[0]}')
{
  (BracedVarSub
    token: <VSub_Name array>
    bracket_op: (ArrayIndex expr:(ArithWord w:{(Lit_Digits 0)}))
    spids: [0 5]
  )
}
('\n---', '${array[5+5]}')
{
  (BracedVarSub
    token: <VSub_Name array>
    bracket_op: 
      (ArrayIndex
        expr: 
          (ArithBinary
            op_id: Arith_Plus
            left: (ArithWord w:{(Lit_Digits 5)})
            right: (ArithWord w:{(Lit_Digits 5)})
          )
      )
    spids: [0 7]
  )
}
('\n---', '${array[@]}')
{(BracedVarSub token:<VSub_Name array> bracket_op:(WholeArray op_id:Lit_At) spids:[0 5])}
('\n---', '${array[*]}')
{(BracedVarSub token:<VSub_Name array> bracket_op:(WholeArray op_id:Arith_Star) spids:[0 5])}
('\n---', '${#}')
{(${ VSub_Pound '#')}
('\n---', '${!}')
{(${ VSub_Bang '!')}
('\n---', '${?}')
{(${ VSub_QMark '?')}
('\n---', '${var}')
{(${ VSub_Name var)}
('\n---', '${15}')
{(${ VSub_Number 15)}
('\n---', '${#var}')
{(BracedVarSub token:<VSub_Name var> prefix_op:VSub_Pound spids:[0 3])}
('\n---', '${!ref}')
{(BracedVarSub token:<VSub_Name ref> prefix_op:VSub_Bang spids:[0 3])}
('\n---', '${##}')
{(BracedVarSub token:<VSub_Pound '#'> prefix_op:VSub_Pound spids:[0 3])}
('\n---', '${array[0]}')
{
  (BracedVarSub
    token: <VSub_Name array>
    bracket_op: (ArrayIndex expr:(ArithWord w:{(Lit_Digits 0)}))
    spids: [0 5]
  )
}
('\n---', '${array[@]}')
{(BracedVarSub token:<VSub_Name array> bracket_op:(WholeArray op_id:Lit_At) spids:[0 5])}
('\n---', '${#array[0]}')
{
  (BracedVarSub
    token: <VSub_Name array>
    prefix_op: VSub_Pound
    bracket_op: (ArrayIndex expr:(ArithWord w:{(Lit_Digits 0)}))
    spids: [0 6]
  )
}
('\n---', '${!array[0]}')
{
  (BracedVarSub
    token: <VSub_Name array>
    prefix_op: VSub_Bang
    bracket_op: (ArrayIndex expr:(ArithWord w:{(Lit_Digits 0)}))
    spids: [0 6]
  )
}
('\n---', '${var#prefix}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{(prefix)})
    spids: [0 4]
  )
}
('\n---', '${!var#prefix}')
{
  (BracedVarSub
    token: <VSub_Name var>
    prefix_op: VSub_Bang
    suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{(prefix)})
    spids: [0 5]
  )
}
('\n---', '${#var#prefix}')
[<Expected } after length expression, got %r ((token id:VOp1_Pound val:'#' span_id:3),) (token id:VOp1_Pound val:'#' span_id:3) None None>, <Error reading command word () (token id:VOp1_Pound val:'#' span_id:3) None None>]
('\n---', '${##2}')
[<Expected } after length expression, got %r ((token id:Unknown_Tok val:2 span_id:3),) (token id:Unknown_Tok val:2 span_id:3) None None>, <Error reading command word () (token id:Unknown_Tok val:2 span_id:3) None None>]
('\n---', '${#@}')
{(BracedVarSub token:<VSub_At '@'> prefix_op:VSub_Pound spids:[0 3])}
('\n---', '${#11}')
{(BracedVarSub token:<VSub_Number 11> prefix_op:VSub_Pound spids:[0 3])}
('\n---', '${#str}')
{(BracedVarSub token:<VSub_Name str> prefix_op:VSub_Pound spids:[0 3])}
('\n---', '${#array[0]}')
{
  (BracedVarSub
    token: <VSub_Name array>
    prefix_op: VSub_Pound
    bracket_op: (ArrayIndex expr:(ArithWord w:{(Lit_Digits 0)}))
    spids: [0 6]
  )
}
('\n---', '${#array["key"]}')
{
  (BracedVarSub
    token: <VSub_Name array>
    prefix_op: VSub_Pound
    bracket_op: (ArrayIndex expr:(ArithWord w:{(DQ (key))}))
    spids: [0 8]
  )
}
--MULTI
('\n---', 'a=(1 2 3)')
{(Lit_VarLike 'a=') (ArrayLiteralPart words:[{(1)} {(2)} {(3)}])}
a=(1 2 3)
0
(line_span line_id:0 col:0 length:2)
('\n---', 'foo')
{(foo)}
foo
0
(line_span line_id:0 col:0 length:3)
('\n---', '\\$')
{(EscapedLiteralPart token:<Lit_EscapedChar '\\$'>)}
\$
0
(line_span line_id:0 col:0 length:2)
('\n---', "''")
{(SQ )}
''
16777215
('\n---', "'sq'")
{(SQ <sq>)}
'sq'
1
(line_span line_id:0 col:1 length:2)
('\n---', '""')
{(DQ )}
""
16777215
('\n---', '"dq"')
{(DQ (dq))}
"dq"
1
(line_span line_id:0 col:1 length:2)
('\n---', '$(echo command sub)')
{
  (CommandSubPart
    command_list: (CommandList children:[(C {(echo)} {(command)} {(sub)})])
    left_token: <Left_CommandSub '$('>
    spids: [0 6]
  )
}
$(echo command sub)
0
(line_span.. line_id:0 col:0 length:2)
('\n---', '$(( 1 + 2 ))')
{
  (ArithSubPart
    anode: 
      (ArithBinary
        op_id: Arith_Plus
        left: (ArithWord w:{(Lit_Digits 1)})
        right: (ArithWord w:{(Lit_Digits 2)})
      )
    spids: [0 9]
  )
}
$(( 1 + 2 ))
0
(line_span line_id:0 col:0 length:3)
('\n---', '~user')
{(Lit_Tilde '~') (user)}
~user
0
(line_span line_id:0 col:0 length:1)
('\n---', '${var#}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{})
    spids: [0 3]
  )
}
${var#}
0
(line_span line_id:0 col:0 length:2)
('\n---', '${var/pat/replace}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} replace:{(replace)} do_all:F do_prefix:F do_suffix:F)
    spids: [0 6]
  )
}
('\n---', '${var//pat/replace}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} replace:{(replace)} do_all:T do_prefix:F do_suffix:F)
    spids: [0 7]
  )
}
('\n---', '${var/%pat/replace}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} replace:{(replace)} do_all:F do_prefix:F do_suffix:T)
    spids: [0 7]
  )
}
('\n---', '${var/#pat/replace}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} replace:{(replace)} do_all:F do_prefix:T do_suffix:F)
    spids: [0 7]
  )
}
('\n---', '${var/pat}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} do_all:F do_prefix:F do_suffix:F)
    spids: [0 4]
  )
}
('\n---', '${var//pat}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} do_all:T do_prefix:F do_suffix:F)
    spids: [0 5]
  )
}
('\n---', '${var/pat//}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} replace:{(Lit_Slash /)} do_all:F do_prefix:F do_suffix:F)
    spids: [0 6]
  )
}
('\n---', '${var/pat///}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: 
      (PatSub
        pat: {(pat)}
        replace: {(Lit_Slash /) (Lit_Slash /)}
        do_all: F
        do_prefix: F
        do_suffix: F
      )
    spids: [0 7]
  )
}
('\n---', '${var/pat/"//"}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (PatSub pat:{(pat)} replace:{(DQ (//))} do_all:F do_prefix:F do_suffix:F)
    spids: [0 8]
  )
}
('\n---', '${var////\\\\/}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: 
      (PatSub
        pat: {(Lit_Slash /)}
        replace: {(EscapedLiteralPart token:<Lit_EscapedChar '\\\\'>) (Lit_Slash /)}
        do_all: T
        do_prefix: F
        do_suffix: F
      )
    spids: [0 8]
  )
}
---
ls "foo"
()
{(ls)}
{(DQ (foo))}
(TokenWord token:<Eof_Real ''>)
---
$(( 1 + 2 ))
()
{
  (ArithSubPart
    anode: 
      (ArithBinary
        op_id: Arith_Plus
        left: (ArithWord w:{(Lit_Digits 1)})
        right: (ArithWord w:{(Lit_Digits 2)})
      )
    spids: [0 9]
  )
}
(TokenWord token:<Eof_Real ''>)
---
$(echo $(( 1 )) )
()
{
  (CommandSubPart
    command_list: 
      (CommandList
        children: [(C {(echo)} {(ArithSubPart anode:(ArithWord w:{(Lit_Digits 1)}) spids:[3 8])})]
      )
    left_token: <Left_CommandSub '$('>
    spids: [0 10]
  )
}
(TokenWord token:<Eof_Real ''>)
---
echo ${#array[@]} b
()
{(echo)}
{
  (BracedVarSub
    token: <VSub_Name array>
    prefix_op: VSub_Pound
    bracket_op: (WholeArray op_id:Lit_At)
    spids: [2 8]
  )
}
{(b)}
(TokenWord token:<Eof_Real ''>)
---
echo $(( ${#array[@]} ))
()
{(echo)}
{
  (ArithSubPart
    anode: 
      (ArithWord
        w: 
          {
            (BracedVarSub
              token: <VSub_Name array>
              prefix_op: VSub_Pound
              bracket_op: (WholeArray op_id:Lit_At)
              spids: [4 10]
            )
          }
      )
    spids: [2 13]
  )
}
(TokenWord token:<Eof_Real ''>)
---
echo ${@%suffix}
()
{(echo)}
{
  (BracedVarSub
    token: <VSub_At '@'>
    suffix_op: (StringUnary op_id:VOp1_Percent arg_word:{(suffix)})
    spids: [2 6]
  )
}
(TokenWord token:<Eof_Real ''>)
---
${@}
()
{(${ VSub_At '@')}
(TokenWord token:<Eof_Real ''>)
---
echo ${var,,}
()
{(echo.)}
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_DComma arg_word:{})
    spids: [2 5]
  )
}
(TokenWord token:<Eof_Real ''>)
---
echo ${var,,?}
()
{(echo)}
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_DComma arg_word:{('?')})
    spids: [2 6]
  )
}
(TokenWord token:<Eof_Real ''>)
---
${\
foo}
()
{(${ VSub_Name foo)}
(TokenWord token:<Eof_Real ''>)
---
${foo\
}
()
{(${ VSub_Name foo)}
(TokenWord token:<Eof_Real ''>)
---
${foo#\
yo}
()
{
  (BracedVarSub
    token: <VSub_Name foo>
    suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{(yo)})
    spids: [0 5]
  )
}
(TokenWord token:<Eof_Real ''>)
---
"${foo#\
yo}"
()
{
  (DQ 
    (BracedVarSub
      token: <VSub_Name foo>
      suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{(yo)})
      spids: [1 6]
    )
  )
}
(TokenWord token:<Eof_Real ''>)
---
1 + 2
()
{(Lit_Digits 1)}
(TokenWord token:<Arith_Plus '+'>)
{(Lit_Digits 2)}
(TokenWord token:<Eof_Real ''>)
---
a + b
()
{(Lit_ArithVarLike a)}
(TokenWord token:<Arith_Plus '+'>)
{(Lit_ArithVarLike b)}
(TokenWord token:<Eof_Real ''>)
---
$a * $b
()
{($ VSub_Name '$a')}
(TokenWord token:<Arith_Star '*'>)
{($ VSub_Name '$b')}
(TokenWord token:<Eof_Real ''>)
---
${a} * ${b}
()
{(${ VSub_Name a)}
(TokenWord token:<Arith_Star '*'>)
{(${ VSub_Name b)}
(TokenWord token:<Eof_Real ''>)
---
$(echo 1) * $(echo 2)
()
{
  (CommandSubPart
    command_list: (CommandList children:[(C {(echo)} {(1)})])
    left_token: <Left_CommandSub '$('>
    spids: [0 4]
  )
}
(TokenWord token:<Arith_Star '*'>)
{
  (CommandSubPart
    command_list: (CommandList children:[(C {(echo)} {(2)})])
    left_token: <Left_CommandSub '$('>
    spids: [8 12]
  )
}
(TokenWord token:<Eof_Real ''>)
---
`echo 1` + 2
()
{
  (CommandSubPart
    command_list: (CommandList children:[(C {(echo)} {(1)})])
    left_token: <Left_Backtick '`'>
    spids: [0 4]
  )
}
(TokenWord token:<Arith_Plus '+'>)
{(Lit_Digits 2)}
(TokenWord token:<Eof_Real ''>)
---
$((1 + 2)) * $((3 + 4))
()
{
  (ArithSubPart
    anode: 
      (ArithBinary
        op_id: Arith_Plus
        left: (ArithWord w:{(Lit_Digits 1)})
        right: (ArithWord w:{(Lit_Digits 2)})
      )
    spids: [0 7]
  )
}
(TokenWord token:<Arith_Star '*'>)
{
  (ArithSubPart
    anode: 
      (ArithBinary
        op_id: Arith_Plus
        left: (ArithWord w:{(Lit_Digits 3)})
        right: (ArithWord w:{(Lit_Digits 4)})
      )
    spids: [11 18]
  )
}
(TokenWord token:<Eof_Real ''>)
---
'single quoted'
()
{(SQ <'single quoted'>)}
(TokenWord token:<Eof_Real ''>)
---
"${a}" + "${b}"
()
{(DQ (${ VSub_Name a))}
(TokenWord token:<Arith_Plus '+'>)
{(DQ (${ VSub_Name b))}
(TokenWord token:<Eof_Real ''>)
---
$# + $$
()
{($ VSub_Pound '$#')}
(TokenWord token:<Arith_Plus '+'>)
{($ VSub_Dollar '$$')}
(TokenWord token:<Eof_Real ''>)
---
$(( x[0] < 5 ))
()
{
  (ArithSubPart
    anode: 
      (ArithBinary
        op_id: Arith_Less
        left: 
          (ArithBinary
            op_id: Arith_LBracket
            left: (ArithVarRef name:x)
            right: (ArithWord w:{(Lit_Digits 0)})
          )
        right: (ArithWord w:{(Lit_Digits 5)})
      )
    spids: [0 12]
  )
}
(TokenWord token:<Eof_Real ''>)
---
$(( ++i ))
()
{(ArithSubPart anode:(UnaryAssign op_id:Arith_DPlus child:(LhsName name:i)) spids:[0 6])}
(TokenWord token:<Eof_Real ''>)
---
$(( i++ ))
()
{(ArithSubPart anode:(UnaryAssign op_id:Node_PostDPlus child:(LhsName name:i)) spids:[0 6])}
(TokenWord token:<Eof_Real ''>)
---
$(( x -= 1))
()
{
  (ArithSubPart
    anode: 
      (BinaryAssign
        op_id: Arith_MinusEqual
        left: (LhsName name:x)
        right: (ArithWord w:{(Lit_Digits 1)})
      )
    spids: [0 8]
  )
}
(TokenWord token:<Eof_Real ''>)
---
$(( x |= 1))
()
{
  (ArithSubPart
    anode: 
      (BinaryAssign
        op_id: Arith_PipeEqual
        left: (LhsName name:x)
        right: (ArithWord w:{(Lit_Digits 1)})
      )
    spids: [0 8]
  )
}
(TokenWord token:<Eof_Real ''>)
---
$(( x[0] = 1 ))
()
{
  (ArithSubPart
    anode: 
      (BinaryAssign
        op_id: Arith_Equal
        left.........
----------------------------------------------------------------------
Ran 16 tests in 0.037s

OK
: (LhsIndexedName name:x index:(ArithWord w:{(Lit_Digits 0)}))
        right: (ArithWord w:{(Lit_Digits 1)})
      )
    spids: [0 12]
  )
}
(TokenWord token:<Eof_Real ''>)
---
$(( 1 | 0 ))
()
{
  (ArithSubPart
    anode: 
      (ArithBinary
        op_id: Arith_Pipe
        left: (ArithWord w:{(Lit_Digits 1)})
        right: (ArithWord w:{(Lit_Digits 0)})
      )
    spids: [0 9]
  )
}
(TokenWord token:<Eof_Real ''>)
---
$((0x$size))
()
{
  (ArithSubPart
    anode: (ArithWord w:{(Lit_Digits 0) (Lit_ArithVarLike x) ($ VSub_Name '$size')})
    spids: [0 5]
  )
}
(TokenWord token:<Eof_Real ''>)
('\n---', '$(( f(x) ))')
{(ArithSubPart anode:(FuncCall func:(ArithVarRef name:f) args:[(ArithVarRef name:x)]) spids:[0 8])}
('\n---', '$(( f(1, 2, 3, 4) ))')
{
  (ArithSubPart
    anode: 
      (FuncCall
        func: (ArithVarRef name:f)
        args: [
          (ArithWord w:{(Lit_Digits 1)})
          (ArithWord w:{(Lit_Digits 2)})
          (ArithWord w:{(Lit_Digits 3)})
          (ArithWord w:{(Lit_Digits 4)})
        ]
      )
    spids: [0 17]
  )
}
('\n---', '${foo:0}')
{
  (BracedVarSub
    token: <VSub_Name foo>
    suffix_op: (Slice begin:(ArithWord w:{(Lit_Digits 0)}))
    spids: [0 4]
  )
}
('\n---', '${foo:0:1}')
{
  (BracedVarSub
    token: <VSub_Name foo>
    suffix_op: (Slice begin:(ArithWord w:{(Lit_Digits 0)}) length:(ArithWord w:{(Lit_Digits 1)}))
    spids: [0 6]
  )
}
('\n---', '${foo:1+2:2+3}')
{
  (BracedVarSub
    token: <VSub_Name foo>
    suffix_op: 
      (Slice
        begin: 
          (ArithBinary
            op_id: Arith_Plus
            left: (ArithWord w:{(Lit_Digits 1)})
            right: (ArithWord w:{(Lit_Digits 2)})
          )
        length: 
          (ArithBinary
            op_id: Arith_Plus
            left: (ArithWord w:{(Lit_Digits 2)})
            right: (ArithWord w:{(Lit_Digits 3)})
          )
      )
    spids: [0 10]
  )
}
('\n---', '${foo::1}')
{
  (BracedVarSub
    token: <VSub_Name foo>
    suffix_op: (Slice length:(ArithWord w:{(Lit_Digits 1)}))
    spids: [0 5]
  )
}
('\n---', '${var:-default]}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VTest_ColonHyphen arg_word:{('default]')})
    spids: [0 4]
  )
}
('\n---', '${var#}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{})
    spids: [0 3]
  )
}
('\n---', '${var#prefix}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{(prefix)})
    spids: [0 4]
  )
}
('\n---', '${var##}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_DPound arg_word:{})
    spids: [0 3]
  )
}
('\n---', '${var##prefix}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_DPound arg_word:{(prefix)})
    spids: [0 4]
  )
}
('\n---', '${var%suffix}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_Percent arg_word:{(suffix)})
    spids: [0 4]
  )
}
('\n---', '${var%%suffix}')
{
  (BracedVarSub
    token: <VSub_Name var>
    suffix_op: (StringUnary op_id:VOp1_DPercent arg_word:{(suffix)})
    spids: [0 4]
  )
}
('\n---', '${name}')
{(${ VSub_Name name)}
('\n---', '${name[0]}')
{
  (BracedVarSub
    token: <VSub_Name name>
    bracket_op: (ArrayIndex expr:(ArithWord w:{(Lit_Digits 0)}))
    spids: [0 5]
  )
}
('\n---', '${array[@]}')
{(BracedVarSub token:<VSub_Name array> bracket_op:(WholeArray op_id:Lit_At) spids:[0 5])}