Mock inotify & test the c-d-c-d-ds-i-ds-i sequence

c = IN_CREATE|IS_DIR
d = IN_DELETE|IS_DIR
ds = IN_DELETE_SELF
i = IN_IGNORE

These are inotify events, not watchdog events

The new test is written in a new module because it required a
different teardown function to stop the emitter before undoing
the mock

tests/test_inotify_c.py

@@ -0,0 +1,117 @@
+from __future__ import unicode_literals
+import os
+import pytest
+import logging
+import contextlib
+from tests import Queue
+from functools import partial
+from .shell import rm, mkdtemp
+from watchdog.utils import platform
+from watchdog.events import DirCreatedEvent, DirDeletedEvent, DirModifiedEvent
+from watchdog.observers.api import ObservedWatch
+
+if platform.is_linux():
+    from watchdog.observers.inotify import InotifyFullEmitter, InotifyEmitter
+
+
+logging.basicConfig(level=logging.DEBUG)
+logger = logging.getLogger(__name__)
+
+
+def setup_function(function):
+    global p, event_queue
+    tmpdir = os.path.realpath(mkdtemp())
+    p = partial(os.path.join, tmpdir)
+    event_queue = Queue()
+
+
+@contextlib.contextmanager
+def watching(path=None, use_full_emitter=False):
+    path = p('') if path is None else path
+    global emitter
+    Emitter = InotifyFullEmitter if use_full_emitter else InotifyEmitter
+    emitter = Emitter(event_queue, ObservedWatch(path, recursive=True))
+    emitter.start()
+    yield
+    emitter.stop()
+    emitter.join(5)
+
+
+def teardown_function(function):
+    rm(p(''), recursive=True)
+    assert not emitter.is_alive()
+
+
+@pytest.mark.skipif(not platform.is_linux(),
+                    reason="Testing with inotify messages (Linux only)")
+def test_late_double_deletion(monkeypatch):
+    inotify_fd = type(str("FD"), (object,), {})() # Empty object
+    inotify_fd.last = 0
+    inotify_fd.wds = []
+
+    # 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"
+    ) * 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"
+    )
+
+    os_read_bkp = os.read
+    def fakeread(fd, length):
+        if fd is inotify_fd:
+            result, fd.buf = fd.buf[:length], fd.buf[length:]
+            return result
+        return os_read_bkp(fd, length)
+
+    os_close_bkp = os.close
+    def fakeclose(fd):
+        if fd is not inotify_fd:
+            os_close_bkp(fd)
+
+    def inotify_init():
+        return inotify_fd
+
+    def inotify_add_watch(fd, path, mask):
+        fd.last += 1
+        logger.debug("New wd = %d" % fd.last)
+        fd.wds.append(fd.last)
+        return fd.last
+
+    def inotify_rm_watch(fd, wd):
+        logger.debug("Removing wd = %d" % wd)
+        fd.wds.remove(wd)
+        return 0
+
+    # Mocks the API!
+    from watchdog.observers import inotify_c
+    monkeypatch.setattr(os, "read", fakeread)
+    monkeypatch.setattr(os, "close", fakeclose)
+    monkeypatch.setattr(inotify_c, "inotify_init", inotify_init)
+    monkeypatch.setattr(inotify_c, "inotify_add_watch", inotify_add_watch)
+    monkeypatch.setattr(inotify_c, "inotify_rm_watch", inotify_rm_watch)
+
+    with watching(p('')):
+        # Watchdog Events
+        for evt_cls in [DirCreatedEvent, DirDeletedEvent] * 2:
+            event = event_queue.get(timeout=5)[0]
+            assert isinstance(event, evt_cls)
+            assert event.src_path == p('subdir1')
+            event = event_queue.get(timeout=5)[0]
+            assert isinstance(event, DirModifiedEvent)
+            assert event.src_path == p('').rstrip(os.path.sep)
+
+    assert inotify_fd.last == 3 # Number of directories
+    assert inotify_fd.buf == b"" # Didn't miss any event
+    assert inotify_fd.wds == [2, 3] # Only 1 is removed explicitly