diff --git a/packages/gapic-generator/gapic/ads-templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2 b/packages/gapic-generator/gapic/ads-templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2
index 8f0bf28f7416..e8953eb0742e 100644
--- a/packages/gapic-generator/gapic/ads-templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2
+++ b/packages/gapic-generator/gapic/ads-templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2
@@ -70,8 +70,10 @@ from google.iam.v1 import policy_pb2  # type: ignore
 {% endfilter %}
 {{ shared_macros.add_google_api_core_version_header_import(service.version) }}
 
+{% if api.all_method_settings.values()|map(attribute="auto_populated_fields", default=[])|list %}
+_UUID4_RE = re.compile(r"{{ uuid4_re }}")
+{% endif %}
 
-{% with uuid4_re = "[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}" %}
 
 def client_cert_source_callback():
     return b"cert bytes", b"key bytes"
@@ -692,7 +694,7 @@ def test_{{ method_name }}_empty_call():
 {% if method_settings is not none %}
 {% for auto_populated_field in method_settings.auto_populated_fields %}
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"{{ uuid4_re }}", args[0].{{ auto_populated_field }})
+        assert _UUID4_RE.match(args[0].{{ auto_populated_field }})
         # clear UUID field so that the check below succeeds
         args[0].{{ auto_populated_field }} = None
 {% endfor %}
@@ -730,7 +732,7 @@ def test_{{ method_name }}_non_empty_request_with_auto_populated_field():
 {% if method_settings is not none %}
 {% for auto_populated_field in method_settings.auto_populated_fields %}
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"{{ uuid4_re }}", args[0].{{ auto_populated_field }})
+        assert _UUID4_RE.match(args[0].{{ auto_populated_field }})
         # clear UUID field so that the check below succeeds
         args[0].{{ auto_populated_field }} = None
 {% endfor %}
@@ -2488,5 +2490,4 @@ def test_client_ctx():
                 pass
             close.assert_called()
 
-{% endwith %}{# uuid4_re #}
 {% endblock %}
diff --git a/packages/gapic-generator/gapic/generator/generator.py b/packages/gapic-generator/gapic/generator/generator.py
index e9e006e74884..9fe56aa9de1d 100644
--- a/packages/gapic-generator/gapic/generator/generator.py
+++ b/packages/gapic-generator/gapic/generator/generator.py
@@ -75,6 +75,9 @@ def __init__(self, opts: Options) -> None:
         self._env.tests["str_field_pb"] = utils.is_str_field_pb
         self._env.tests["msg_field_pb"] = utils.is_msg_field_pb
 
+        # Add global variables.
+        self._env.globals["uuid4_re"] = utils.UUID4_RE
+
         self._sample_configs = opts.sample_configs
 
     def get_response(self, api_schema: api.API, opts: Options) -> CodeGeneratorResponse:
diff --git a/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2 b/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2
index ea93a9b48c26..bd5d5a42ff7f 100644
--- a/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2
+++ b/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_%service.py.j2
@@ -106,6 +106,9 @@ CRED_INFO_JSON = {
     "principal": "service-account@example.com",
 }
 CRED_INFO_STRING = json.dumps(CRED_INFO_JSON)
+{% if api.all_method_settings.values()|map(attribute="auto_populated_fields", default=[])|list %}
+_UUID4_RE = re.compile(r"{{ uuid4_re }}")
+{% endif %}
 
 
 async def mock_async_gen(data, chunk_size=1):
diff --git a/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_macros.j2 b/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_macros.j2
index c3dfea385b17..648f2e868812 100644
--- a/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_macros.j2
+++ b/packages/gapic-generator/gapic/templates/tests/unit/gapic/%name_%version/%sub/test_macros.j2
@@ -150,7 +150,7 @@ def test_{{ method_name }}_non_empty_request_with_auto_populated_field():
 {% if method_settings is not none %}
 {% for auto_populated_field in method_settings.auto_populated_fields %}
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"{{ get_uuid4_re() }}", args[0].{{ auto_populated_field }})
+        assert _UUID4_RE.fullmatch(args[0].{{ auto_populated_field }})
         request_msg.{{ auto_populated_field }} = args[0].{{ auto_populated_field }}
 {% endfor %}
 {% endif %}{# if method_settings is not none #}
@@ -1208,7 +1208,7 @@ def test_{{ method_name }}_rest_required_fields(request_type={{ method.input.ide
             # Ensure that the uuid4 field is set according to AIP 4235
             for i, (key, value) in enumerate(req.call_args.kwargs['params']):
                 if key == "{{ auto_populated_field|camel_case }}":
-                    assert re.fullmatch(r"{{ get_uuid4_re() }}", value)
+                    assert _UUID4_RE.match(value)
                     break
             
             # Include {{ auto_populated_field|camel_case }} within expected_params with value mock.ANY
@@ -1565,7 +1565,7 @@ def test_{{ method_name }}_rest_no_http_options():
         {% if method_settings is not none %}
         {% for auto_populated_field in method_settings.auto_populated_fields %}
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"{{ get_uuid4_re() }}", args[0].{{ auto_populated_field }})
+        assert _UUID4_RE.fullmatch(args[0].{{ auto_populated_field }})
         request_msg.{{ auto_populated_field }} = args[0].{{ auto_populated_field }}
         {% endfor %}{# for auto_populated_field in method_settings.auto_populated_fields #}
         {% endif %}{# if method_settings is not none #}
@@ -2196,7 +2196,7 @@ def test_initialize_client_w_{{transport_name}}():
 {% endmacro %}{# empty_call_test #}
 
 {% macro get_uuid4_re() -%}
-[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}
+{{ uuid4_re }}
 {%- endmacro %}{# uuid_re #}
 
 {% macro routing_parameter_test(service, api, transport, is_async) %}
diff --git a/packages/gapic-generator/gapic/utils/__init__.py b/packages/gapic-generator/gapic/utils/__init__.py
index 23c573915695..18d78c31dd1e 100644
--- a/packages/gapic-generator/gapic/utils/__init__.py
+++ b/packages/gapic-generator/gapic/utils/__init__.py
@@ -22,6 +22,7 @@
 from gapic.utils.code import nth
 from gapic.utils.code import partition
 from gapic.utils.code import make_private
+from gapic.utils.constants import UUID4_RE
 from gapic.utils.doc import doc
 from gapic.utils.filename import to_valid_filename
 from gapic.utils.filename import to_valid_module_name
@@ -52,5 +53,6 @@
     "to_camel_case",
     "to_valid_filename",
     "to_valid_module_name",
+    "UUID4_RE",
     "wrap",
 )
diff --git a/packages/gapic-generator/gapic/utils/constants.py b/packages/gapic-generator/gapic/utils/constants.py
new file mode 100644
index 000000000000..e21f7cd2170f
--- /dev/null
+++ b/packages/gapic-generator/gapic/utils/constants.py
@@ -0,0 +1,16 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# The regex for a UUID4 as specified in AIP-4235.
+UUID4_RE = r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}"
diff --git a/packages/gapic-generator/tests/integration/goldens/storagebatchoperations/tests/unit/gapic/storagebatchoperations_v1/test_storage_batch_operations.py b/packages/gapic-generator/tests/integration/goldens/storagebatchoperations/tests/unit/gapic/storagebatchoperations_v1/test_storage_batch_operations.py
index 51af4c7b84d7..f25a28395082 100755
--- a/packages/gapic-generator/tests/integration/goldens/storagebatchoperations/tests/unit/gapic/storagebatchoperations_v1/test_storage_batch_operations.py
+++ b/packages/gapic-generator/tests/integration/goldens/storagebatchoperations/tests/unit/gapic/storagebatchoperations_v1/test_storage_batch_operations.py
@@ -74,6 +74,7 @@
     "principal": "service-account@example.com",
 }
 CRED_INFO_STRING = json.dumps(CRED_INFO_JSON)
+_UUID4_RE = re.compile(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}")
 
 
 async def mock_async_gen(data, chunk_size=1):
@@ -1947,7 +1948,7 @@ def test_create_job_non_empty_request_with_auto_populated_field():
             job_id='job_id_value',
         )
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -2293,7 +2294,7 @@ def test_delete_job_non_empty_request_with_auto_populated_field():
             name='name_value',
         )
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -2606,7 +2607,7 @@ def test_cancel_job_non_empty_request_with_auto_populated_field():
             name='name_value',
         )
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -4204,7 +4205,7 @@ def test_create_job_rest_required_fields(request_type=storage_batch_operations.C
             # Ensure that the uuid4 field is set according to AIP 4235
             for i, (key, value) in enumerate(req.call_args.kwargs['params']):
                 if key == "requestId":
-                    assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", value)
+                    assert _UUID4_RE.match(value)
                     break
 
             # Include requestId within expected_params with value mock.ANY
@@ -4382,7 +4383,7 @@ def test_delete_job_rest_required_fields(request_type=storage_batch_operations.D
             # Ensure that the uuid4 field is set according to AIP 4235
             for i, (key, value) in enumerate(req.call_args.kwargs['params']):
                 if key == "requestId":
-                    assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", value)
+                    assert _UUID4_RE.match(value)
                     break
 
             # Include requestId within expected_params with value mock.ANY
@@ -4558,7 +4559,7 @@ def test_cancel_job_rest_required_fields(request_type=storage_batch_operations.C
             # Ensure that the uuid4 field is set according to AIP 4235
             for i, (key, value) in enumerate(req.call_args.kwargs['params']):
                 if key == "requestId":
-                    assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", value)
+                    assert _UUID4_RE.match(value)
                     break
 
             # Include requestId within expected_params with value mock.ANY
@@ -5193,7 +5194,7 @@ def test_create_job_empty_call_grpc():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.CreateJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -5218,7 +5219,7 @@ def test_delete_job_empty_call_grpc():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.DeleteJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -5243,7 +5244,7 @@ def test_cancel_job_empty_call_grpc():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.CancelJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -5388,7 +5389,7 @@ async def test_create_job_empty_call_grpc_asyncio():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.CreateJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -5415,7 +5416,7 @@ async def test_delete_job_empty_call_grpc_asyncio():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.DeleteJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -5443,7 +5444,7 @@ async def test_cancel_job_empty_call_grpc_asyncio():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.CancelJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -6695,7 +6696,7 @@ def test_create_job_empty_call_rest():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.CreateJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -6719,7 +6720,7 @@ def test_delete_job_empty_call_rest():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.DeleteJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg
 
@@ -6743,7 +6744,7 @@ def test_cancel_job_empty_call_rest():
         _, args, _ = call.mock_calls[0]
         request_msg = storage_batch_operations.CancelJobRequest()
         # Ensure that the uuid4 field is set according to AIP 4235
-        assert re.fullmatch(r"[a-f0-9]{8}-?[a-f0-9]{4}-?4[a-f0-9]{3}-?[89ab][a-f0-9]{3}-?[a-f0-9]{12}", args[0].request_id)
+        assert _UUID4_RE.fullmatch(args[0].request_id)
         request_msg.request_id = args[0].request_id
         assert args[0] == request_msg