Fix test mocks for big endian systems

Fix the mocked inotify data to respect system endianness.  Instead of
harcoding the raw data, reconstruct it using struct.pack(), respecting
host endianness.  This should also benefit readability a bit.

Closes #804

changelog.rst

@@ -13,7 +13,8 @@ Changelog
 - [mac] Convert absolute watch path in ``FSEeventsEmitter`` with ``os.path.realpath()``. (`#822 <https://github.com/gorakhargosh/watchdog/pull/822>`_)
 - Fix a possible ``AttributeError`` in ``SkipRepeatsQueue._put()``. (`#818 <https://github.com/gorakhargosh/watchdog/pull/818>`_)
 - Allow overriding or adding custom event handlers to event dispatch map. (`#814 <https://github.com/gorakhargosh/watchdog/pull/814>`_)
-- Thanks to our beloved contributors: @replabrobin, @BoboTiG, @SamSchott, @AndreiB97, @NiklasRosenstein, @ikokollari
+- Fix tests on big endian platforms. (`#828 <https://github.com/gorakhargosh/watchdog/pull/828>`_)
+- Thanks to our beloved contributors: @replabrobin, @BoboTiG, @SamSchott, @AndreiB97, @NiklasRosenstein, @ikokollari, @mgorny
 
 2.1.3
 ~~~~~

tests/test_inotify_c.py

@@ -10,13 +10,14 @@
 import errno
 import logging
 import os
+import struct
 from functools import partial
 from queue import Queue
 
 from watchdog.events import DirCreatedEvent, DirDeletedEvent, DirModifiedEvent
 from watchdog.observers.api import ObservedWatch
 from watchdog.observers.inotify import InotifyFullEmitter, InotifyEmitter
-from watchdog.observers.inotify_c import Inotify
+from watchdog.observers.inotify_c import Inotify, InotifyConstants
 
 from .shell import mkdtemp, rm
 
@@ -52,28 +53,37 @@ def teardown_function(function):
         pass
 
 
+def struct_inotify(wd, mask, cookie=0, length=0, name=b""):
+    assert len(name) <= length
+    struct_format = (
+        "="  # (native endianness, standard sizes)
+        "i"  # int      wd
+        "i"  # uint32_t mask
+        "i"  # uint32_t cookie
+        "i"  # uint32_t len
+        "%ds" % (length,)  # char[] name
+    )
+    return struct.pack(struct_format, wd, mask, cookie, length, name)
+
+
 def test_late_double_deletion(monkeypatch):
     inotify_fd = type(str("FD"), (object,), {})()  # Empty object
     inotify_fd.last = 0
     inotify_fd.wds = []
 
+    const = InotifyConstants()
+
     # CREATE DELETE CREATE DELETE DELETE_SELF IGNORE DELETE_SELF IGNORE
     inotify_fd.buf = (
-        # IN_CREATE|IS_DIR (wd = 1, path = subdir1)
-        b"\x01\x00\x00\x00\x00\x01\x00\x40\x00\x00\x00\x00\x10\x00\x00\x00"
-        b"\x73\x75\x62\x64\x69\x72\x31\x00\x00\x00\x00\x00\x00\x00\x00\x00"
-        # IN_DELETE|IS_DIR (wd = 1, path = subdir1)
-        b"\x01\x00\x00\x00\x00\x02\x00\x40\x00\x00\x00\x00\x10\x00\x00\x00"
-        b"\x73\x75\x62\x64\x69\x72\x31\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+        struct_inotify(wd=1, mask=const.IN_CREATE | const.IN_ISDIR,
+                       length=16, name=b"subdir1")
+        + struct_inotify(wd=1, mask=const.IN_DELETE | const.IN_ISDIR,
+                         length=16, name=b"subdir1")
     ) * 2 + (
-        # IN_DELETE_SELF (wd = 2)
-        b"\x02\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
-        # IN_IGNORE (wd = 2)
-        b"\x02\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
-        # IN_DELETE_SELF (wd = 3)
-        b"\x03\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
-        # IN_IGNORE (wd = 3)
-        b"\x03\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+        struct_inotify(wd=2, mask=const.IN_DELETE_SELF)
+        + struct_inotify(wd=2, mask=const.IN_IGNORED)
+        + struct_inotify(wd=3, mask=const.IN_DELETE_SELF)
+        + struct_inotify(wd=3, mask=const.IN_IGNORED)
     )
 
     os_read_bkp = os.read