Add unit tests for spack graph command (#6778)

lib/spack/spack/test/cmd/graph.py

+##############################################################################
+# Copyright (c) 2013-2017, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/spack/spack
+# Please also see the NOTICE and LICENSE files for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# 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 terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+from spack.main import SpackCommand, SpackCommandError
+
+import pytest
+
+
+graph = SpackCommand('graph')
+
+
+def test_graph_ascii(builtin_mock, database):
+    """Tests spack graph --ascii"""
+
+    graph('--ascii', 'dt-diamond')
+
+
+def test_graph_dot(builtin_mock, database):
+    """Tests spack graph --dot"""
+
+    graph('--dot', 'dt-diamond')
+
+
+def test_graph_normalize(builtin_mock, database):
+    """Tests spack graph --normalize"""
+
+    graph('--normalize', 'dt-diamond')
+
+
+def test_graph_static(builtin_mock, database):
+    """Tests spack graph --static"""
+
+    graph('--static', 'dt-diamond')
+
+
+def test_graph_installed(builtin_mock, database):
+    """Tests spack graph --installed"""
+
+    graph('--installed')
+
+    with pytest.raises(SpackCommandError):
+        graph('--installed', 'dt-diamond')
+
+
+def test_graph_deptype(builtin_mock, database):
+    """Tests spack graph --deptype"""
+
+    graph('--deptype', 'all', 'dt-diamond')
+
+
+def test_graph_no_specs():
+    """Tests spack graph with no arguments"""
+
+    with pytest.raises(SpackCommandError):
+        graph()