"expect" match "send" string, why? - shell

Question

I found that expect command just after send command match data from send command.
Let see, my.sh:
#!/bin/sh
read line
echo ok
my.exp (some code is redundant, I emulate DejaGNU testing framework...):
set passn 0
proc pass {msg} { global passn; incr passn; send_user "PASS: $msg\n" }
set failn 0
proc fail {msg} { global failn; incr failn; send_user "FAIL: $msg\n" }
proc check {} {
global passn failn;
send_user "TOTOAL: [expr $passn + $failn], PASSED: $passn, FAIL: $failn\n"
if {$failn == 0} { exit 0 } { exit 1 }
}
set timeout 1
spawn ./my.sh
send hello\n
expect {
-ex hello {
send_user "~$expect_out(0,string)~\n"
pass hello
}
default { fail hello }
}
expect {
-ex ok { pass ok }
default { fail ok }
}
check
When run expect my.exp I get:
spawn ./my.sh
hello
~hello~
PASS: hello
ok
PASS: ok
TOTOAL: 2, PASSED: 2, FAIL: 0
I don't understand why hello matched!! Please tell me. I already reread:
http://expect.sourceforge.net/FAQ.html

Answer 1

expect works with
pseudoterminal devices. They are
much like normal terminals: unless you disable echo (using expect's
stty command), whatever you send is also visible as your "terminal
output" (which is expect's input).
stty_init variable is used by expect to set up newly created
pseudoterminals. If you add set stty_init -echo to the beginnig of
my.exp, the test will begin to fail.