Tests: added exception test to stream_js.t using 'require'.

The stream js tests introduced in edf5a3c9e36a fail on njs 0.1.14.  It doesn't
currently provide an easy way to check its version, whilst we are obligated to
gracefully handle such cases somehow.  With such an addition of 'require', now
the tests are skipped instead on the previous versions.

Author: pluknet

stream_js.t

@@ -109,6 +109,12 @@ stream {
         js_filter   js_filter_except;
         proxy_pass  127.0.0.1:8090;
     }
+
+    server {
+        listen      127.0.0.1:8093;
+        js_preread  js_preread_except;
+        proxy_pass  127.0.0.1:8090;
+    }
 }
 
 EOF
@@ -181,14 +187,19 @@ $t->write_file('functions.js', <<EOF);
         res += '3';
     }
 
+    function js_preread_except(sess) {
+        var fs = require('fs');
+        fs.readFileSync();
+    }
+
     function js_filter_except(sess) {
         sess.a.a;
     }
 
 EOF
 
 $t->run_daemon(\&stream_daemon, port(8090));
-$t->try_run('no stream njs available')->plan(13);
+$t->try_run('no stream njs available')->plan(14);
 $t->waitforsocket('127.0.0.1:' . port(8090));
 
 ###############################################################################
@@ -208,10 +219,13 @@ is(stream('127.0.0.1:' . port(8088))->io('xyz'), 'xyz', 'js_preread');
 is(stream('127.0.0.1:' . port(8089))->io('x'), 'z', 'js_filter');
 is(stream('127.0.0.1:' . port(8091))->io('0'), '01233', 'handlers order');
 stream('127.0.0.1:' . port(8092))->io('x');
+stream('127.0.0.1:' . port(8093))->io('x');
 
 $t->stop();
 
 ok(index($t->read_file('error.log'), 'SEE-THIS') > 0, 'stream js log');
+ok(index($t->read_file('error.log'), 'at fs.readFileSync') > 0,
+   'stream js_preread backtrace');
 ok(index($t->read_file('error.log'), 'at js_filter_except') > 0,
    'stream js_filter backtrace');