diff --git a/git-graph-tests.el b/git-graph-tests.el
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+++ b/git-graph-tests.el
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+;;; git-graph-tests.el ---Tests for git-graph.el -*- lexical-binding: t -*-
+
+;; Copyright (c) 2015 Correl Roush <correl@gmail.com>
+
+;;; License:
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+;; Boston, MA 02110-1301, USA.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'ert)
+(require 'git-graph)
+
+;; 1---2---5---6---7 [master]
+;;      \     /
+;;       3---4 [topic]
+(ert-deftest automatically-group-nodes ()
+  (let* ((example-graph
+          (git-graph/group-topo
+           (list (git-graph/make-node 7 '(6) '((label . master)))
+                 (git-graph/make-node 6 '(5 4))
+                 (git-graph/make-node 5 '(2))
+                 (git-graph/make-node 4 '(3) '((label . topic)))
+                 (git-graph/make-node 3 '(2))
+                 (git-graph/make-node 2 '(1))
+                 (git-graph/make-node 1 '()))))
+         (master-nodes (seq-map #'git-graph/node-id
+                                (seq-filter (lambda (node) (eq 7 (git-graph/node-group node)))
+                                            example-graph)))
+         (topic-nodes (seq-map #'git-graph/node-id
+                               (seq-filter (lambda (node) (eq 4 (git-graph/node-group node)))
+                                           example-graph))))
+    (should (equal '(7 6 5 2 1) master-nodes))
+    (should (equal '(4 3) topic-nodes))))
+
+;;; git-graph-tests.el ends here