From 272221e6fcadda71b95487931286666da810ceda Mon Sep 17 00:00:00 2001
From: Vojtech Juranek <vjuranek@redhat.com>
Date: Jun 17 2019 13:12:10 +0000
Subject: tests: replace reading of magic number by helper function


Introduce helper function for reading sanlock magic numbers. This
helper function seeks to specified offset in given file and reads
unsigned int from this position.

---

diff --git a/tests/python_test.py b/tests/python_test.py
index 3242f57..58d94c9 100644
--- a/tests/python_test.py
+++ b/tests/python_test.py
@@ -86,12 +86,9 @@ def test_write_lockspace(tmpdir, sanlock_daemon, filename, encoding, size, offse
         b"ls_name", 1, path, offset=offset, wait=False)
     assert acquired is False
 
-    with io.open(path, "rb") as f:
-        f.seek(offset)
-        magic, = struct.unpack("< I", f.read(4))
-        assert magic == constants.DELTA_DISK_MAGIC
-
-        # TODO: check more stuff here...
+    magic = util.read_magic(path, offset)
+    assert magic == constants.DELTA_DISK_MAGIC
+    # TODO: check more stuff here...
 
     util.check_guard(path, size)
 
@@ -117,9 +114,8 @@ def test_write_lockspace_4k(user_4k_path, sanlock_daemon, align):
     assert acquired is False
 
     # Verify that lockspace was written.
-    with io.open(user_4k_path, "rb") as f:
-        magic, = struct.unpack("< I", f.read(4))
-        assert magic == constants.DELTA_DISK_MAGIC
+    magic = util.read_magic(user_4k_path)
+    assert magic == constants.DELTA_DISK_MAGIC
 
     # Check that sanlock did not write beyond the lockspace area.
     util.check_guard(user_4k_path, align)
@@ -179,10 +175,8 @@ def test_write_resource(tmpdir, sanlock_daemon, filename, encoding, size, offset
     owners = sanlock.read_resource_owners(b"ls_name", b"res_name", disks)
     assert owners == []
 
-    with io.open(path, "rb") as f:
-        f.seek(offset)
-        magic, = struct.unpack("< I", f.read(4))
-        assert magic == constants.PAXOS_DISK_MAGIC
+    magic = util.read_magic(path, offset)
+    assert magic == constants.PAXOS_DISK_MAGIC
 
         # TODO: check more stuff here...
 
@@ -216,9 +210,8 @@ def test_write_resource_4k(sanlock_daemon, user_4k_path, align):
     assert owners == []
 
     # Verify that resource was written.
-    with io.open(user_4k_path, "rb") as f:
-        magic, = struct.unpack("< I", f.read(4))
-        assert magic == constants.PAXOS_DISK_MAGIC
+    magic = util.read_magic(user_4k_path)
+    assert magic == constants.PAXOS_DISK_MAGIC
 
     # Check that sanlock did not write beyond the lockspace area.
     util.check_guard(user_4k_path, align)
diff --git a/tests/util.py b/tests/util.py
index 08db236..243b1d3 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -177,3 +177,14 @@ def sanlock_is_running():
         if e.errno != errno.ENOENT:
             raise
     return False
+
+
+def read_magic(path, offset=0):
+    """
+    Read and return unsigned int from specified file at given offset.
+    Typical usage is to read sanlock magic number.
+    """
+    with io.open(path, "rb") as f:
+        f.seek(offset)
+        uint, = struct.unpack("< I", f.read(4))
+        return uint