name: "IFS"
cases:
  - name: "Default IFS value"
    stdin: |
      # Default IFS is space, tab, newline
      [[ "$IFS" == $' \t\n' ]] && echo "IFS has default value"

  - name: "Field splitting with default IFS"
    stdin: |
      var="one two	three
      four"
      echo "Fields:" $var

  - name: "Field splitting with custom single-char IFS"
    stdin: |
      IFS=':'
      var="one:two:three"
      echo $var

  - name: "Field splitting with multi-char IFS"
    stdin: |
      IFS=':,'
      var="one:two,three:four"
      echo $var

  - name: "Empty IFS disables field splitting"
    stdin: |
      IFS=''
      var="one two	three"
      echo "[$var]"
      # Should print with all whitespace preserved

  - name: "Empty IFS with expansion"
    stdin: |
      IFS=''
      var="a b c"
      set -- $var
      echo "Count: $#"
      echo "[$1]"

  - name: "Unset IFS uses default splitting"
    stdin: |
      unset IFS
      var="one two	three"
      echo $var

  - name: "IFS whitespace vs non-whitespace splitting"
    known_failure: true
    stdin: |
      # Non-whitespace IFS chars create empty fields
      IFS=':'
      var=":one::two:"
      set -- $var
      echo "Count: $#"
      echo "Args: $@"

  - name: "IFS whitespace splitting ignores leading/trailing"
    stdin: |
      # Whitespace IFS chars ignore leading/trailing
      IFS=' '
      var="  one  two  "
      set -- $var
      echo "Count: $#"
      echo "Args: $@"

  - name: "Mixed whitespace and non-whitespace IFS"
    stdin: |
      IFS=' :'
      var="one:two  three : four"
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "Mixed IFS leading non-whitespace"
    known_failure: true
    stdin: |
      IFS=': '
      var=":one: :two"
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "Mixed IFS trailing non-whitespace"
    stdin: |
      IFS=' :'
      var="one :two: "
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "IFS only whitespace multiple chars"
    stdin: |
      IFS=$' \t'
      var="  one		two  	three  "
      set -- $var
      echo "Count: $#"
      echo "Args: $@"

  - name: "IFS only non-whitespace multiple chars"
    known_failure: true
    stdin: |
      IFS=':,'
      var=":,one,:,two,:"
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "IFS only tab character"
    stdin: |
      IFS=$'\t'
      var="		a		b		"
      set -- $var
      echo "Count: $#"
      echo "Args: $@"

  - name: "IFS only newline character"
    stdin: |
      IFS=$'\n'
      var="

      a

      b

      "
      set -- $var
      echo "Count: $#"
      echo "Args: $@"

  - name: "IFS affects command substitution"
    stdin: |
      IFS=':'
      result=$(echo "a:b:c")
      # Command substitution itself doesn't split, but expansion does
      set -- $result
      echo "$#"
      echo "$@"

  - name: "IFS with command substitution multiline"
    stdin: |
      IFS=$'\n'
      result=$(printf "a\nb\nc")
      set -- $result
      echo "Count: $#"
      echo "$1|$2|$3"

  - name: "IFS affects arithmetic expansion"
    stdin: |
      IFS=' '
      # Arithmetic expansion result is splittable
      set -- $((1 + 1)) $((2 + 2))
      echo "Count: $#"
      echo "$@"

  - name: "IFS in array expansion"
    stdin: |
      arr=(one two three)
      IFS=':'
      echo "${arr[*]}"
      # With $* should join with first char of IFS

  - name: "IFS with $* vs $@"
    stdin: |
      set -- one two three
      IFS=':'
      echo "$*"
      echo "$@"

  - name: "IFS with $* unquoted"
    stdin: |
      set -- "a:b" "c:d"
      IFS=':'
      # Unquoted $* joins then splits
      set -- $*
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "IFS null char handling"
    stdin: |
      IFS=':'
      var=""
      set -- $var
      echo "Empty var count: $#"

  - name: "IFS preservation across commands"
    stdin: |
      IFS=':'
      echo "First: $IFS"
      var="a:b"
      echo $var
      echo "After: $IFS"

  - name: "IFS in subshell"
    stdin: |
      IFS=':'
      (
        echo "In subshell: [$IFS]"
        var="a:b:c"
        set -- $var
        echo "Count: $#"
      )
      echo "Parent: [$IFS]"

  - name: "IFS local to command"
    stdin: |
      var="a:b:c"
      IFS=':' echo $var
      # IFS assignment should only affect that command
      echo "After: [$IFS]"

  - name: "IFS does not affect for loop literal words"
    # hydrashell: fixed by ExpansionPiece::LiteralText (literal words are not field-split)
    stdin: |
      IFS=':'
      for word in a:b:c; do
        echo "[$word]"
      done

  - name: "IFS affects for loop variable expansion"
    stdin: |
      IFS=':'
      var="a:b:c"
      for word in $var; do
        echo "[$word]"
      done

  - name: "IFS affects for loop command substitution"
    stdin: |
      IFS=':'
      for word in $(echo "x:y:z"); do
        echo "[$word]"
      done

  - name: "IFS with quoted vs unquoted expansion"
    stdin: |
      IFS=':'
      var="a:b:c"
      echo "Unquoted:" $var
      echo "Quoted: $var"

  - name: "IFS with partially quoted expansion"
    # hydrashell: fixed by ExpansionPiece::LiteralText (literal words are not field-split)
    stdin: |
      IFS=':'
      var="a:b:c"
      set -- "$var":more
      echo "Count: $#"
      echo "$@"

  - name: "IFS whitespace sequence handling"
    stdin: |
      IFS=' '
      var="a    b"
      set -- $var
      echo "Count: $#"
      echo "Args: $@"

  - name: "IFS non-whitespace sequence handling"
    known_failure: true
    stdin: |
      IFS=':'
      var="a::::b"
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "IFS with parameter expansion"
    stdin: |
      IFS=':'
      var="a:b:c"
      result=${var}
      set -- $result
      echo "$#"
      echo "$@"

  - name: "IFS with parameter expansion default value"
    stdin: |
      IFS=':'
      set -- ${unset:-a:b:c}
      echo "Count: $#"
      echo "$@"

  - name: "IFS with parameter expansion empty default"
    stdin: |
      IFS=':'
      set -- ${unset:-}
      echo "Count: $#"

  - name: "IFS with parameter length"
    stdin: |
      IFS=':'
      var="a:b:c"
      # Length expansion returns a number, not subject to further splitting
      len=${#var}
      set -- $len
      echo "Count: $#"
      echo "[$1]"

  - name: "IFS with glob pattern literal"
    # hydrashell: fixed by ExpansionPiece::LiteralText (literal words are not field-split)
    stdin: |
      IFS=':'
      # Glob patterns as literals shouldn't split
      for word in *.txt:*.sh; do
        echo "[$word]"
      done

  - name: "IFS newline handling"
    stdin: |
      IFS=$'\n'
      var="a
      b
      c"
      set -- $var
      echo "Count: $#"
      echo "$1|$2|$3"

  - name: "IFS tab handling"
    stdin: |
      IFS=$'\t'
      var="a	b	c"
      set -- $var
      echo "Count: $#"
      echo "$1|$2|$3"

  - name: "IFS with backslash in value"
    stdin: |
      IFS=':'
      var='a\:b:c\:d'
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "IFS first char for joining"
    stdin: |
      set -- a b c
      IFS=':'
      # First char of IFS used for $* joining
      result="$*"
      echo "[$result]"

  - name: "IFS first char empty IFS"
    known_failure: true
    stdin: |
      set -- a b c
      IFS=''
      result="$*"
      echo "[$result]"

  - name: "IFS multiple whitespace at start"
    stdin: |
      IFS=' '
      var="     a b"
      set -- $var
      echo "Count: $#"
      echo "$@"

  - name: "IFS multiple whitespace at end"
    stdin: |
      IFS=' '
      var="a b     "
      set -- $var
      echo "Count: $#"
      echo "$@"

  - name: "IFS with read builtin integration"
    stdin: |
      IFS=':'
      echo "a:b:c" | (read x y z; echo "x=[$x] y=[$y] z=[$z]")

  - name: "IFS whitespace before non-whitespace"
    known_failure: true
    stdin: |
      IFS=' :'
      var=" :a"
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done

  - name: "IFS non-whitespace before whitespace"
    known_failure: true
    stdin: |
      IFS=': '
      var=": a"
      set -- $var
      echo "Count: $#"
      for arg in "$@"; do
        echo "[$arg]"
      done