vlib: fix tcp_test.v

The listen_tcp method should not accept .unix af.
Test that it indeed fails when invoked.

vlib/net/tcp_test.v

@@ -1,7 +1,4 @@
-// vtest flaky: true
-// vtest retry: 8
 import net
-import os
 
 const test_port = 45123
 
@@ -25,14 +22,11 @@ fn one_shot_echo_server(mut l net.TcpListener, ch_started chan int) ! {
 	mut new_conn := l.accept() or { return error('could not accept') }
 	eprintln('    > new_conn: ${new_conn}')
 	handle_conn(mut new_conn)
-	new_conn.close() or {}
+	new_conn.close() or { panic(err) }
 }
 
 fn echo(address string) ! {
 	mut c := net.dial_tcp(address)!
-	defer {
-		c.close() or {}
-	}
 
 	println('local: ' + c.addr()!.str())
 	println(' peer: ' + c.peer_addr()!.str())
@@ -46,6 +40,7 @@ fn echo(address string) ! {
 		assert buf[i] == data[i]
 	}
 	println('Got "${buf.bytestr()}"')
+	c.close()!
 }
 
 fn test_tcp_ip6() {
@@ -55,7 +50,7 @@ fn test_tcp_ip6() {
 	dump(l)
 	start_echo_server(mut l)
 	echo(address) or { panic(err) }
-	l.close() or {}
+	l.close() or { panic(err) }
 	// ensure there is at least one new socket created before the next test
 	l = net.listen_tcp(.ip6, ':${test_port + 1}') or { panic(err) }
 }
@@ -73,26 +68,16 @@ fn test_tcp_ip() {
 	dump(l)
 	start_echo_server(mut l)
 	echo(address) or { panic(err) }
-	l.close() or {}
+	l.close() or { panic(err) }
 }
 
 fn test_tcp_unix() {
 	eprintln('\n>>> ${@FN}')
-	// TODO(emily):
-	// whilst windows supposedly supports unix sockets
-	// this doesnt work (wsaeopnotsupp at the call to bind())
-	$if !windows {
-		address := os.real_path('tcp-test.sock')
-		// address := 'tcp-test.sock'
-		println('${address}')
-
-		mut l := net.listen_tcp(.unix, address) or { panic(err) }
-		start_echo_server(mut l)
-		echo(address) or { panic(err) }
-		l.close() or {}
+	address := 'tcp-test.sock'
+	eprintln('${address}')
 
-		os.rm(address) or { panic('failed to remove socket file') }
-	}
+	mut l := net.listen_tcp(.unix, address) or { return }
+	assert false
 }
 
 fn testsuite_end() {
@@ -103,6 +88,6 @@ fn test_bind() {
 	$if !network ? {
 		return
 	}
-	mut conn := net.dial_tcp_with_bind('vlang.io:80', '127.0.0.1:0')!
-	conn.close()!
+	mut conn := net.dial_tcp_with_bind('vlang.io:80', '127.0.0.1:0') or { panic(err) }
+	conn.close() or { panic(err) }
 }