fix(er): include nonlocals in snapshots (DataDog#11894)

We include nonlocal variables in snapshots to provide for better
visibility into exception occurrences.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [ ] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Author: P403n1x87

Diff for: ddtrace/debugging/_safety.py

@@ -1,5 +1,6 @@
 from inspect import CO_VARARGS
 from inspect import CO_VARKEYWORDS
+from itertools import chain
 from types import FrameType
 from typing import Any
 from typing import Dict
@@ -23,11 +24,11 @@ def get_args(frame: FrameType) -> Iterator[Tuple[str, Any]]:
 
 def get_locals(frame: FrameType) -> Iterator[Tuple[str, Any]]:
     code = frame.f_code
+    _locals = frame.f_locals
     nargs = code.co_argcount + bool(code.co_flags & CO_VARARGS) + bool(code.co_flags & CO_VARKEYWORDS)
-    names = code.co_varnames[nargs:]
-    values = (frame.f_locals.get(name) for name in names)
-
-    return zip(names, values)
+    return (
+        (name, _locals.get(name)) for name in chain(code.co_varnames[nargs:], code.co_freevars, code.co_cellvars)
+    )  # include freevars and cellvars
 
 
 def get_globals(frame: FrameType) -> Iterator[Tuple[str, Any]]:

Diff for: releasenotes/notes/fix-er-include-nonlocals-bbeecfbbbde35496.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    exception replay: include missing nonlocal variables in snapshot log messages.

Diff for: tests/debugging/exception/test_replay.py

@@ -294,3 +294,23 @@ def c(foo=42):
             self.assert_span_count(6)
             # no new snapshots
             assert len(uploader.collector.queue) == 3
+
+    def test_debugger_exception_in_closure(self):
+        def b():
+            with self.trace("b"):
+                nonloc = 4
+
+                def a(v):
+                    if nonloc:
+                        raise ValueError("hello", v)
+
+                a(nonloc)
+
+        with exception_replay() as uploader:
+            with with_rate_limiter(RateLimiter(limit_rate=1, raise_on_exceed=False)):
+                with pytest.raises(ValueError):
+                    b()
+
+            assert all(
+                s.line_capture["locals"]["nonloc"] == {"type": "int", "value": "4"} for s in uploader.collector.queue
+            )

Diff for: tests/debugging/test_safety.py

@@ -15,7 +15,10 @@ def assert_args(args):
         assert set(dict(_safety.get_args(inspect.currentframe().f_back)).keys()) == args
 
     def assert_locals(_locals):
-        assert set(dict(_safety.get_locals(inspect.currentframe().f_back)).keys()) == _locals
+        assert set(dict(_safety.get_locals(inspect.currentframe().f_back)).keys()) == _locals | {
+            "assert_args",
+            "assert_locals",
+        }
 
     def assert_globals(_globals):
         assert set(dict(_safety.get_globals(inspect.currentframe().f_back)).keys()) == _globals