new file mode 100644
--- /dev/null
+++ b/stream_js_send.t
@@ -0,0 +1,192 @@
+#!/usr/bin/perl
+
+# (C) Dmitry Volyntsev
+# (C) Nginx, Inc.
+
+# Tests for s.send() in stream njs module.
+
+###############################################################################
+
+use warnings;
+use strict;
+
+use Test::More;
+
+BEGIN { use FindBin; chdir($FindBin::Bin); }
+
+use lib 'lib';
+use Test::Nginx;
+use Test::Nginx::Stream qw/ stream /;
+
+###############################################################################
+
+select STDERR; $| = 1;
+select STDOUT; $| = 1;
+
+my $t = Test::Nginx->new()->has(qw/http stream/)
+	->write_file_expand('nginx.conf', <<'EOF');
+
+%%TEST_GLOBALS%%
+
+daemon off;
+
+events {
+}
+
+http {
+    %%TEST_GLOBALS_HTTP%%
+
+    js_import test.js;
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  localhost;
+
+        location /njs {
+            js_content test.njs;
+        }
+    }
+}
+
+stream {
+    %%TEST_GLOBALS_STREAM%%
+
+    js_import test.js;
+
+    server {
+        listen      127.0.0.1:8081;
+        js_filter   test.filter;
+        proxy_pass  127.0.0.1:8090;
+    }
+
+    server {
+        listen      127.0.0.1:8082;
+        js_filter   test.filter_direct;
+        proxy_pass  127.0.0.1:8090;
+    }
+}
+
+EOF
+
+$t->write_file('test.js', <<EOF);
+    function test_njs(r) {
+        r.return(200, njs.version);
+    }
+
+    function filter(s) {
+      s.on("upload", async (data, flags) => {
+        s.send("__HANDSHAKE__", flags);
+
+        const p = new Promise((resolve, reject) => {
+              s.on("download", (data, flags) => {
+                  s.off("download");
+                  resolve(data);
+              });
+        });
+
+        s.off("upload");
+
+        const handshakeResponse = await p;
+        if (handshakeResponse != '__HANDSHAKE_RESPONSE__') {
+            throw `Handshake failed: \${handshakeResponse}`;
+        }
+
+        s.send(data, flags);
+      });
+    }
+
+    function filter_direct(s) {
+      s.on("upload", async (data, flags) => {
+        s.sendUpstream("__HANDSHAKE__", flags);
+
+        const p = new Promise((resolve, reject) => {
+              s.on("download", (data, flags) => {
+                  s.off("download");
+                  resolve(data);
+              });
+        });
+
+        s.off("upload");
+
+        const handshakeResponse = await p;
+        if (handshakeResponse != '__HANDSHAKE_RESPONSE__') {
+            throw `Handshake failed: \${handshakeResponse}`;
+        }
+
+        s.sendDownstream('xxx', flags);
+        s.sendUpstream(data, flags);
+      });
+    }
+
+    export default {njs:test_njs, filter, filter_direct};
+
+EOF
+
+$t->run_daemon(\&stream_daemon, port(8090));
+$t->try_run('no stream njs available')->plan(2);
+$t->waitforsocket('127.0.0.1:' . port(8090));
+
+###############################################################################
+
+TODO: {
+local $TODO = 'not yet'
+	unless http_get('/njs') =~ /^([.0-9]+)$/m && $1 ge '0.7.8';
+
+is(stream('127.0.0.1:' . port(8081))->io('abc'), 'ABC',
+	'async filter');;
+is(stream('127.0.0.1:' . port(8082))->io('abc'), 'xxxABC',
+	'async filter direct');
+
+}
+
+$t->stop();
+
+###############################################################################
+
+sub stream_daemon {
+	my $server = IO::Socket::INET->new(
+		Proto => 'tcp',
+		LocalAddr => '127.0.0.1:' . port(8090),
+		Listen => 5,
+		Reuse => 1
+	)
+		or die "Can't create listening socket: $!\n";
+
+	local $SIG{PIPE} = 'IGNORE';
+
+	while (my $client = $server->accept()) {
+		$client->autoflush(1);
+
+		log2c("(new connection $client)");
+
+		$client->sysread(my $buffer, 65536) or next;
+
+		log2i("$client $buffer");
+
+		if ($buffer ne "__HANDSHAKE__") {
+			$buffer = "__HANDSHAKE_INVALID__";
+			log2o("$client $buffer");
+			$client->syswrite($buffer);
+
+			close $client;
+		}
+
+		$buffer = "__HANDSHAKE_RESPONSE__";
+		log2o("$client $buffer");
+		$client->syswrite($buffer);
+
+		$client->sysread($buffer, 65536) or next;
+
+		$buffer = uc($buffer);
+		log2o("$client $buffer");
+		$client->syswrite($buffer);
+
+		close $client;
+	}
+}
+
+sub log2i { Test::Nginx::log_core('|| <<', @_); }
+sub log2o { Test::Nginx::log_core('|| >>', @_); }
+sub log2c { Test::Nginx::log_core('||', @_); }
+
+###############################################################################