fix(flask): flask 2.2.0 removes (#4026) (#4028)

This is an automatic backport of pull request #4026 done by [Mergify](https://mergify.com).
Cherry-pick of d957850 has failed:
```
On branch mergify/bp/1.3/pr-4026
Your branch is up to date with 'origin/1.3'.

You are currently cherry-picking commit d957850.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   ddtrace/contrib/flask/patch.py
	new file:   releasenotes/notes/fix-attribute-error-in-flask-2.2.0-94524c33b005d48a.yaml
	modified:   tests/contrib/flask/test_hooks.py
	modified:   tests/contrib/flask/test_request.py
	modified:   tests/contrib/flask/test_static.py
	modified:   tests/contrib/flask/test_template.py
	modified:   tests/contrib/flask_autopatch/test_flask_autopatch.py
	new file:   tests/snapshots/tests.contrib.flask.test_flask_snapshot.test_flask_200_220.json
	new file:   tests/snapshots/tests.contrib.flask.test_flask_snapshot.test_flask_stream_220.json

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   tests/contrib/flask/test_flask_snapshot.py

```


To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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Author: mergify[bot]

ddtrace/contrib/flask/patch.py

@@ -102,11 +102,13 @@ def patch():
         "handle_exception",
         "handle_http_exception",
         "handle_user_exception",
-        "try_trigger_before_first_request_functions",
         "do_teardown_request",
         "do_teardown_appcontext",
         "send_static_file",
     ]
+    if flask_version < (2, 2, 0):
+        flask_app_traces.append("try_trigger_before_first_request_functions")
+
     for name in flask_app_traces:
         _w("flask", "Flask.{}".format(name), simple_tracer("flask.{}".format(name)))
 
@@ -184,7 +186,6 @@ def unpatch():
         "Flask.handle_exception",
         "Flask.handle_http_exception",
         "Flask.handle_user_exception",
-        "Flask.try_trigger_before_first_request_functions",
         "Flask.do_teardown_request",
         "Flask.do_teardown_appcontext",
         "Flask.send_static_file",
@@ -236,6 +237,10 @@ def unpatch():
         props.append("appcontext_popped.receivers_for")
         props.append("message_flashed.receivers_for")
 
+    # These were removed in 2.2.0
+    if flask_version < (2, 2, 0):
+        props.append("Flask.try_trigger_before_first_request_functions")
+
     for prop in props:
         # Handle 'flask.request_started.receivers_for'
         obj = flask

releasenotes/notes/fix-attribute-error-in-flask-2.2.0-94524c33b005d48a.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Flask: version 2.2.0 removes ``try_trigger_before_first_request_functions``

tests/contrib/flask/test_hooks.py

@@ -1,11 +1,15 @@
 from flask import Blueprint
 
+from ddtrace.contrib.flask.patch import flask_version
 from ddtrace.ext import http
 from tests.utils import assert_span_http_status_code
 
 from . import BaseFlaskTestCase
 
 
+REMOVED_SPANS_2_2_0 = 1 if flask_version >= (2, 2, 0) else 0
+
+
 class FlaskHookTestCase(BaseFlaskTestCase):
     def setUp(self):
         super(FlaskHookTestCase, self).setUp()
@@ -35,7 +39,7 @@ def before_request():
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         # DEV: This will raise an exception if this span doesn't exist
         self.find_span_by_name(spans, "flask.dispatch_request")
@@ -68,7 +72,7 @@ def before_request():
         self.assertEqual(req.data, b"Not Allowed")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 7)
+        self.assertEqual(len(spans), 7 - REMOVED_SPANS_2_2_0)
 
         dispatch = self.find_span_by_name(spans, "flask.dispatch_request", required=False)
         self.assertIsNone(dispatch)
@@ -112,7 +116,7 @@ def before_first_request():
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.before_first_request")
         parent = self.find_span_parent(spans, span)
@@ -124,15 +128,18 @@ def before_first_request():
         self.assertEqual(span.get_tags(), dict())
 
         # Assert correct parent span
-        self.assertEqual(parent.name, "flask.try_trigger_before_first_request_functions")
+        if flask_version >= (2, 2, 0):
+            self.assertEqual(parent.name, "flask.request")
+        else:
+            self.assertEqual(parent.name, "flask.try_trigger_before_first_request_functions")
 
         # Make a second request to ensure a span isn't created
         req = self.client.get("/")
         self.assertEqual(req.status_code, 200)
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 8)
+        self.assertEqual(len(spans), 8 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.before_first_request", required=False)
         self.assertIsNone(span)
@@ -152,7 +159,7 @@ def after_request(response):
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.after_request")
         parent = self.find_span_parent(spans, span)
@@ -182,7 +189,7 @@ def after_request(response):
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         root = self.find_span_by_name(spans, "flask.request")
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.after_request")
@@ -215,7 +222,7 @@ def teardown_request(request):
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.teardown_request")
         parent = self.find_span_parent(spans, span)
@@ -244,7 +251,7 @@ def teardown_appcontext(appctx):
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.teardown_appcontext")
         parent = self.find_span_parent(spans, span)
@@ -274,7 +281,7 @@ def bp_before_request():
         self.assertEqual(req.data, b"Hello Blueprint")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.bp_before_request")
         parent = self.find_span_parent(spans, span)
@@ -304,7 +311,7 @@ def bp_before_app_request():
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.bp_before_app_request")
         parent = self.find_span_parent(spans, span)
@@ -334,7 +341,7 @@ def bp_before_app_first_request():
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.bp_before_app_first_request")
         parent = self.find_span_parent(spans, span)
@@ -346,15 +353,18 @@ def bp_before_app_first_request():
         self.assertEqual(span.get_tags(), dict())
 
         # Assert correct parent span
-        self.assertEqual(parent.name, "flask.try_trigger_before_first_request_functions")
+        if flask_version >= (2, 2, 0):
+            self.assertEqual(parent.name, "flask.request")
+        else:
+            self.assertEqual(parent.name, "flask.try_trigger_before_first_request_functions")
 
         # Make a second request to ensure a span isn't created
         req = self.client.get("/")
         self.assertEqual(req.status_code, 200)
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 8)
+        self.assertEqual(len(spans), 8 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(
             spans,
@@ -379,7 +389,7 @@ def bp_after_request(response):
         self.assertEqual(req.data, b"Hello Blueprint")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.bp_after_request")
         parent = self.find_span_parent(spans, span)
@@ -409,7 +419,7 @@ def bp_after_app_request(response):
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.bp_after_app_request")
         parent = self.find_span_parent(spans, span)
@@ -439,7 +449,7 @@ def bp_teardown_request(request):
         self.assertEqual(req.data, b"Hello Blueprint")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.bp_teardown_request")
         parent = self.find_span_parent(spans, span)
@@ -469,7 +479,7 @@ def bp_teardown_app_request(request):
         self.assertEqual(req.data, b"Hello Flask")
 
         spans = self.get_spans()
-        self.assertEqual(len(spans), 9)
+        self.assertEqual(len(spans), 9 - REMOVED_SPANS_2_2_0)
 
         span = self.find_span_by_name(spans, "tests.contrib.flask.test_hooks.bp_teardown_app_request")
         parent = self.find_span_parent(spans, span)