Optional logging of active Node handles in gulp

This commit adds optional logging of open sockets, file handles, etc.
to the gulp script. Logging happens after various NodeJS test task
that can theoretically leave unclosed resources after execution.
Logging is turned off by default. It happened to be very useful when
NodeJS process does not exit after tests because of
open `TLSSocket` objects.

Author: lutovich

gulpfile.babel.js

@@ -48,6 +48,11 @@ var file = require('gulp-file');
 var semver = require('semver');
 var sharedNeo4j = require('./test/internal/shared-neo4j').default;
 
+/**
+ * Useful to investigate resource leaks in tests. Enable to see active sockets and file handles after the 'test' task.
+ */
+var enableActiveNodeHandlesLogging = false;
+
 gulp.task('default', ["test"]);
 
 gulp.task('browser', function(cb){
@@ -165,15 +170,15 @@ gulp.task('test-nodejs', ['install-driver-into-sandbox'], function () {
     .pipe(jasmine({
       includeStackTrace: true,
       verbose: true
-    }));
+    })).on('end', logActiveNodeHandles);
 });
 
 gulp.task('test-boltkit', ['nodejs'], function () {
   return gulp.src('test/**/*.boltkit.it.js')
     .pipe(jasmine({
       includeStackTrace: true,
       verbose: true
-    }));
+    })).on('end', logActiveNodeHandles);
 });
 
 gulp.task('test-browser', function (cb) {
@@ -210,7 +215,7 @@ gulp.task('run-tck', ['download-tck', 'nodejs'], function() {
         'steps': 'test/v1/tck/steps/*.js',
         'format': 'progress',
         'tags' : ['~@fixed_session_pool', '~@db', '~@equality', '~@streaming_and_cursor_navigation']
-    }));
+    })).on('end', logActiveNodeHandles);
 });
 
 /** Set the project version, controls package.json and version.js */
@@ -248,5 +253,11 @@ gulp.task('run-stress-tests', function () {
     .pipe(jasmine({
       includeStackTrace: true,
       verbose: true
-    }));
+    })).on('end', logActiveNodeHandles);
 });
+
+function logActiveNodeHandles() {
+  if (enableActiveNodeHandlesLogging) {
+    console.log('-- Active NodeJS handles START\n', process._getActiveHandles(), '\n-- Active NodeJS handles END');
+  }
+}