ref(init): Deprecate sentry_sdk.init context manager (#3729)

It is possible to use the return value of `sentry_sdk.init` as a context manager; however, this functionality has not been maintained for a long time, and it does not seem to be documented anywhere.

So, we are deprecating this functionality, and we will remove it in the next major release.

Closes #3282

sentry_sdk/_init_implementation.py

@@ -1,3 +1,5 @@
+import warnings
+
 from typing import TYPE_CHECKING
 
 import sentry_sdk
@@ -9,16 +11,35 @@
 
 
 class _InitGuard:
+    _CONTEXT_MANAGER_DEPRECATION_WARNING_MESSAGE = (
+        "Using the return value of sentry_sdk.init as a context manager "
+        "and manually calling the __enter__ and __exit__ methods on the "
+        "return value are deprecated. We are no longer maintaining this "
+        "functionality, and we will remove it in the next major release."
+    )
+
     def __init__(self, client):
         # type: (sentry_sdk.Client) -> None
         self._client = client
 
     def __enter__(self):
         # type: () -> _InitGuard
+        warnings.warn(
+            self._CONTEXT_MANAGER_DEPRECATION_WARNING_MESSAGE,
+            stacklevel=2,
+            category=DeprecationWarning,
+        )
+
         return self
 
     def __exit__(self, exc_type, exc_value, tb):
         # type: (Any, Any, Any) -> None
+        warnings.warn(
+            self._CONTEXT_MANAGER_DEPRECATION_WARNING_MESSAGE,
+            stacklevel=2,
+            category=DeprecationWarning,
+        )
+
         c = self._client
         if c is not None:
             c.close()

tests/test_api.py

@@ -1,6 +1,7 @@
 import pytest
 from unittest import mock
 
+import sentry_sdk
 from sentry_sdk import (
     capture_exception,
     continue_trace,
@@ -195,3 +196,19 @@ def test_push_scope_deprecation():
     with pytest.warns(DeprecationWarning):
         with push_scope():
             ...
+
+
+def test_init_context_manager_deprecation():
+    with pytest.warns(DeprecationWarning):
+        with sentry_sdk.init():
+            ...
+
+
+def test_init_enter_deprecation():
+    with pytest.warns(DeprecationWarning):
+        sentry_sdk.init().__enter__()
+
+
+def test_init_exit_deprecation():
+    with pytest.warns(DeprecationWarning):
+        sentry_sdk.init().__exit__(None, None, None)