name: "Command substitution"
cases:
  - name: "Command substitution"
    stdin: |
      var="value"

      echo "1:"
      echo $(echo hi)
      echo "2:"
      echo "$(echo hi)"
      echo "3:"
      echo "$(echo "hi")"
      echo "4:"
      echo "$(var="updated"; echo ${var})"
      echo "var=${var}"

  - name: "Command substitution with embedded parens"
    stdin: |
      x=$(echo foo | (wc -l; echo hi))
      echo "\$x: $x"

  - name: "Command substitution with subshell"
    stdin: |
      x=$( (echo hi) )
      echo "\$x: $x"

  - name: "Command substitution exit code"
    stdin: |
      x=$(false) && echo "1. Made it past false"
      y=$(true) && echo "2. Made it past true"

  - name: "Command substitution with exec"
    stdin: |
      x=$(exec echo hi)
      echo "x: $x"

  - name: "Backtick command substitution"
    stdin: |
      echo `echo hi`

  - name: "Backtick command substitution with escaping"
    stdin: |
      echo `echo \`echo hi\``

  - name: "Backtick command substitution with backslashes"
    stdin: |
      echo `echo \\`

  - name: "Backtick command substitution in double quotes"
    stdin: |
      echo "`echo First line`"
      echo " `echo Second line` "
      echo "Third`echo line`here"

  - name: "Ignore single quote in comment in command substitution"
    stdin: |
      var=$(
        # I'm
        echo "Batman"
      )
      echo $var

  - name: "Ignore double quote in comment in command substitution"
    stdin: |
      var=$(
        # This " is not being
        echo "parsed"
      )
      echo $var

  - name: "Ignore parentheses in comment in command substitution"
    stdin: |
      var=$(
        # :(
        echo "Sad"
      )
      echo $var

  - name: "Ignore dollar in comment in command substitution"
    stdin: |
      var=$(
        #               $
        echo "Mr. Crabs ^"
      )
      echo $var

  - name: "Positional parameter count not mistaken for comment"
    stdin: |
      echo $(echo $#)

  - name: "Ignore single quote in comment in command substitution (backticks)"
    stdin: |
      var=`
        # I'm
        echo "Batman"
      `
      echo $var

  - name: "Ignore double quote in comment in command substitution (backticks)"
    stdin: |
      var=`
        # This " is not being
        echo "parsed"
      `
      echo $var

  - name: "Ignore parentheses in comment in command substitution (backticks)"
    stdin: |
      var=`
        # :(
        echo "Sad"
      `
      echo $var

  - name: "Ignore dollar in comment in command substitution (backticks)"
    stdin: |
      var=`
        #               $
        echo "Mr. Crabs ^"
      `
      echo $var

  - name: "Positional parameter count not mistaken for comment (backticks)"
    stdin: |
      echo `echo $#`

  - name: "Command substitution with only input redir"
    stdin: |
      echo "Some text" >file.txt
      x=$(<file.txt)
      echo "x: $x"

  - name: "Command substitution with only input redir in pipeline"
    known_failure: true
    ignore_stderr: true
    test_files:
      - path: file.txt
        contents: |
          File Contents
    stdin: |
      x=$(<non-existent-file.txt) || x=$(<file.txt)
      echo "\$?: $?"
      echo "x: $x"

  - name: "Backquote with only input redir"
    stdin: |
      echo "Some text" >file.txt
      x=`<file.txt`
      echo "x: $x"

  - name: "Command substitution as simple command preserves exit code"
    stdin: |
      $(false)
      echo "exit code: $?"

      $(true)
      echo "exit code: $?"

      $(exit 42)
      echo "exit code: $?"

  - name: "Backtick substitution as simple command preserves exit code"
    stdin: |
      `false`
      echo "exit code: $?"

      `true`
      echo "exit code: $?"

  - name: "Command substitution with exec as simple command"
    stdin: |
      $(exec true)
      echo "exit code: $?"

      $(exec false)
      echo "exit code: $?"

  - name: "Command substitution strips null bytes"
    ignore_stderr: true
    stdin: |
      echo "$(echo -e 'a\x00b')" | hexdump -C

  - name: "Backtick substitution strips null bytes"
    ignore_stderr: true
    stdin: |
      echo "`echo -e 'a\x00b'`" | hexdump -C

  - name: "Command substitution strips multiple null bytes"
    ignore_stderr: true
    stdin: |
      echo "$(echo -e 'hello\x00world\x00end')" | hexdump -C

  - name: "Command substitution with only null bytes produces empty string"
    ignore_stderr: true
    stdin: |
      echo "$(echo -e '\x00\x00\x00')" | hexdump -C

  - name: "Variable assignment from command substitution strips null bytes"
    ignore_stderr: true
    stdin: |
      x=$(echo -e 'a\x00b')
      echo "$x" | hexdump -C

  - name: "Input redirection substitution strips null bytes"
    ignore_stderr: true
    stdin: |
      printf 'a\x00b' > file.txt
      x=$(<file.txt)
      echo "$x" | hexdump -C

  - name: "Nested command substitution strips null bytes"
    ignore_stderr: true
    stdin: |
      echo "$(echo "$(echo -e 'a\x00b')")" | hexdump -C

  - name: "Nested command substitution exit code"
    stdin: |
      $($(false))
      echo "exit code: $?"

      $($(:))
      echo "exit code: $?"