raise a LockError when the context manager fails to acquire a lockv3-breaking-changes

Fixes #621
Fixes #927

2 files changed, 9 insertions, 2 deletions

diff --git a/redis/lock.py b/redis/lock.py
index fb73ce2..05d4153 100644
--- a/redis/lock.py
+++ b/redis/lock.py
@@ -125,8 +125,9 @@ class Lock(object):
     def __enter__(self):
         # force blocking, as otherwise the user would have to check whether
         # the lock was actually acquired or not.
-        self.acquire(blocking=True)
-        return self
+        if self.acquire(blocking=True):
+            return self
+        raise LockError("Unable to acquire lock within the time specified")
 
     def __exit__(self, exc_type, exc_value, traceback):
         self.release()
diff --git a/tests/test_lock.py b/tests/test_lock.py
index 9cbc2f8..a9ecf54 100644
--- a/tests/test_lock.py
+++ b/tests/test_lock.py
@@ -56,6 +56,12 @@ class TestLock(object):
             assert r.get('foo') == lock.local.token
         assert r.get('foo') is None
 
+    def test_context_manager_raises_when_locked_not_acquired(self, r):
+        r.set('foo', 'bar')
+        with pytest.raises(LockError):
+            with self.get_lock(r, 'foo', blocking_timeout=0.1):
+                pass
+
     def test_high_sleep_raises_error(self, r):
         "If sleep is higher than timeout, it should raise an error"
         with pytest.raises(LockError):