Capture exit code of Expect script - error-handling

Question

I have an expect script that will transfer the file from one server to another. This expect script is being kicked off by the shell script. The expect script can transfer the file if it is available in source and it will give a zero exit code. However, when the file is not available in source, the script will not transfer the file but it will still give a zero exit code.
How can I capture the correct exit code of the expect script.
test.sh:
#!/bin/sh
DT=`date +%Y%m%d`
RXHOME=/tmp'
x_server=A1234
x_file="test_${DT}.dat"
cd $RXHOME/scripts
./test.exp ${x_server} ${x_file}
if [ $? -ne 0 ]
then
echo "ERROR : Expect script encountered an error."
exit 1
fi
test.exp:
#!/usr/local/bin/expect -f
set timeout -1
set XSERVER [lindex $argv 0]
set XFILE [lindex $argv 1]
set uid "user"
set pwd "password"
set srcDir "/tmp/src"
set trgDir "/tmp/trg"
spawn /usr/ldir/bin/sftp ${uid}#${XSERVER}
expect -re "Are you sure you want to continue connecting (yes/no)?" {
send -- "yes\r"
expect -re "assword: "
send -- "$pwd\r"
} -re "assword: " {
send -- "$pwd\r"
}
expect -re "sftp> "
send -- "put ${srcDir}/${XFILE} ${trgDir}/test_file.txt\r"
expect "sftp> "
send -- "bye\r"
expect eof
catch wait result
exit [lindex $result 3]
Sample Output when there is no file available in source:
+ + date +%Y%m%d
DT=20160919
+ RXHOME=/tmp
+ x_server=A1234
+ x_file=test_20160919.dat
+ cd /tmp/scripts
+ ./test.exp A1234 test_20160919.dat
spawn /usr/ldir/bin/sftp user#A1234
Connecting to A1234...
user#A1234's password:
sftp> put /tmp/src/test_20160919.dat /tmp/trg/test_file.txt
File "/tmp/src/test_20160919.dat" not found.
sftp> bye
+ [ 0 -ne 0 ]
$
As you can see, even if there is no file transferred to target since it's not available in source, the script still exited with zero exit code.

Answer 1

You have to handle the error by yourself. Try like this:
set err 0
send -- "put ${srcDir}/${XFILE} ${trgDir}/test_file.txt\r"
expect {
-re "File .* not found" {
set err 1
exp_continue
}
"sftp> "
}
send -- "bye\r"
expect eof
exit $err

Answer 2

Why don't you just check that the file exists before spawning sftp?
set srcFile [file join $srcDir $XFILE]
if {! [file exists $srcFile]} {
puts stderr "File not found in source: $XFILE"
exit 1
}
spawn /usr/ldir/bin/sftp ${uid}#${XSERVER}
...