Bring back test for the qcow2 file format

tests/compute/qemu/test_qcow2.py

@@ -0,0 +1,73 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2016 GNS3 Technologies Inc.
+#
+# 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 of the License, 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import pytest
+import shutil
+import asyncio
+
+from gns3server.compute.qemu.qcow2 import Qcow2, Qcow2Error
+
+
+def qemu_img():
+    """
+    Return the path of qemu-img on system.
+    We can't use shutil.which because for safety reason we break
+    the PATH to avoid test interacting with real binaries
+    """
+    paths = [
+        "/usr/bin/qemu-img",
+        "/usr/local/bin/qemu-img"
+    ]
+    for path in paths:
+        if os.path.exists(path):
+            return path
+    return None
+
+
+def test_valid_base_file():
+    qcow2 = Qcow2("tests/resources/empty8G.qcow2")
+    assert qcow2.version == 3
+    assert qcow2.backing_file is None
+
+
+def test_valid_linked_file():
+    qcow2 = Qcow2("tests/resources/linked.qcow2")
+    assert qcow2.version == 3
+    assert qcow2.backing_file == "empty8G.qcow2"
+
+
+def test_invalid_file():
+    with pytest.raises(Qcow2Error):
+        Qcow2("tests/resources/nvram_iou")
+
+
+def test_invalid_empty_file(tmpdir):
+    open(str(tmpdir / 'a'), 'w+').close()
+    with pytest.raises(Qcow2Error):
+        Qcow2(str(tmpdir / 'a'))
+
+
+@pytest.mark.skipif(qemu_img() is None, reason="qemu-img is not available")
+def test_rebase(tmpdir, loop):
+    shutil.copy("tests/resources/empty8G.qcow2", str(tmpdir / "empty16G.qcow2"))
+    shutil.copy("tests/resources/linked.qcow2", str(tmpdir / "linked.qcow2"))
+    qcow2 = Qcow2(str(tmpdir / "linked.qcow2"))
+    assert qcow2.version == 3
+    assert qcow2.backing_file == "empty8G.qcow2"
+    loop.run_until_complete(asyncio.async(qcow2.rebase(qemu_img(), str(tmpdir / "empty16G.qcow2"))))
+    assert qcow2.backing_file == str(tmpdir / "empty16G.qcow2")