new file mode 100644
--- /dev/null
+++ b/stream_js_fetch.t
@@ -0,0 +1,156 @@
+#!/usr/bin/perl
+
+# (C) Dmitry Volyntsev
+# (C) Nginx, Inc.
+
+# Tests for stream njs module, fetch method.
+
+###############################################################################
+
+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 $t = Test::Nginx->new()->has(qw/http stream/)
+	->write_file_expand('nginx.conf', <<'EOF');
+
+%%TEST_GLOBALS%%
+
+daemon off;
+
+events {
+}
+
+http {
+    %%TEST_GLOBALS_HTTP%%
+
+    js_import test.js;
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  localhost;
+
+        location /njs {
+            js_content test.njs;
+        }
+    }
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  aaa;
+
+        location /validate {
+            js_content test.validate;
+        }
+    }
+}
+
+stream {
+    %%TEST_GLOBALS_STREAM%%
+
+    js_import test.js;
+
+    server {
+        listen      127.0.0.1:8081;
+        js_preread  test.preread_verify;
+        proxy_pass  127.0.0.1:8090;
+    }
+}
+
+EOF
+
+$t->write_file('test.js', <<EOF);
+    function test_njs(r) {
+        r.return(200, njs.version);
+    }
+
+    function validate(r) {
+        r.return((r.requestText == 'QZ') ? 200 : 403);
+    }
+
+    function preread_verify(s) {
+        var collect = Buffer.from([]);
+
+        s.on('upstream', function (data, flags) {
+            collect = Buffer.concat([collect, data]);
+
+            if (collect.length >= 4 && collect.readUInt16BE(0) == 0xabcd) {
+                s.off('upstream');
+                ngx.fetch('http://127.0.0.1:8080/validate',
+                          {body: collect.slice(2,4), headers: {Host:'aaa'}})
+                .then(reply => (reply.status == 200) ? s.done(): s.deny())
+
+            } else if (collect.length) {
+                s.deny();
+            }
+        });
+    }
+
+    export default {njs: test_njs, validate, preread_verify}
+EOF
+
+$t->try_run('no stream njs available')->plan(4);
+
+$t->run_daemon(\&stream_daemon, port(8090));
+$t->waitforsocket('127.0.0.1:' . port(8090));
+
+###############################################################################
+
+local $TODO = 'not yet'
+	unless http_get('/njs') =~ /^([.0-9]+)$/m && $1 ge '0.5.1';
+
+is(stream('127.0.0.1:' . port(8081))->io('###'), '', 'preread not enough');
+is(stream('127.0.0.1:' . port(8081))->io("\xAB\xCDQZ##"), "\xAB\xCDQZ##",
+	'preread validated');
+is(stream('127.0.0.1:' . port(8081))->io("\xAC\xCDQZ##"), '',
+	'preread invalid magic');
+is(stream('127.0.0.1:' . port(8081))->io("\xAB\xCDQQ##"), '',
+	'preread validation failed');
+
+###############################################################################
+
+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 $buffer");
+
+		log2o("$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('||', @_); }
+
+###############################################################################