use generated async-rest constraints files

Author: daniel-sanche

gapic/templates/testing/constraints-3.9-async-rest.txt.j2

@@ -0,0 +1,25 @@
+{% set rest_async_io_enabled = api.all_library_settings[api.naming.proto_package].python_settings.experimental_features.rest_async_io_enabled %}
+{% if rest_async_io_enabled %}
+# -*- coding: utf-8 -*-
+{% from '_pypi_packages.j2' import pypi_packages %}
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List all library dependencies and extras in this file,
+# pinning their versions to their lower bounds.
+# For example, if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0",
+# then this file should have google-cloud-foo==1.14.0
+google-api-core==2.21.0
+google-auth==2.35.0
+# TODO(https://github.com/googleapis/gapic-generator-python/issues/2453)
+# Add the minimum supported version of grpcio to constraints files
+proto-plus==1.22.3
+protobuf==4.25.8
+{% for package_tuple, package_info in pypi_packages.items() %}
+{# Quick check to make sure `package_info.package_name` is not the package being generated so we don't circularly include this package in its own constraints file. #}
+{% if api.naming.warehouse_package_name != package_info.package_name %}
+{% if api.requires_package(package_tuple) %}
+{{ package_info.package_name }}=={{ package_info.lower_bound }}
+{% endif %}
+{% endif %}
+{% endfor %}
+{% endif %}

noxfile.py

@@ -357,35 +357,21 @@ def showcase_library(
             constraints_path = str(
                 f"{tmp_dir}/testing/constraints-{session.python}.txt"
             )
-            if not rest_async_io_enabled:
-                # Install the library with a constraints file.
-                session.install("-e", tmp_dir, "-r", constraints_path)
-            else:
-                # Modify constraints file to support async_rest min constraints.
-                # TODO: Move into own contraints-async-rest.txt file once 
-                # async-rest is fully supported
-                async_rest_constraints = {
-                    "google-auth": "2.35.0",
-                    "google-api-core": "2.21.0",
-                }
-                with open(constraints_path) as f:
-                    constraints_lines = [
-                        line.strip()
-                        for line in f
-                        if line.strip() and not line.startswith("#")
-                    ]
-                # Only modify dependencies in the original constraints file.
-                replace_keys = {
-                    key for key in async_rest_constraints
-                    if any(line.startswith(key) for line in constraints_lines)
-                }
-                # Replace async_rest constraints in final output.
-                constraints = [
-                    line for line in constraints_lines
-                    if not any(line.startswith(key) for key in replace_keys)
-                ] + [f"{k}=={async_rest_constraints[k]}" for k in replace_keys]
-
-                session.install("-e", f"{tmp_dir}[async_rest]", *constraints)
+            extras = ""
+            if rest_async_io_enabled:
+                async_rest_constraints_path = str(
+                    f"{tmp_dir}/testing/constraints-3.9-async-rest.txt"
+                )
+                if os.path.exists(async_rest_constraints_path):
+                    # use async-rest constraints if available
+                    constraints_path = async_rest_constraints_path
+                else:
+                    session.log(
+                        f"{async_rest_constraints_path} not found. Using base constraints file"
+                    )
+                extras = "[async_rest]"
+
+            session.install("-e", f"{tmp_dir}{extras}", "-r", constraints_path)
         else:
             # The ads templates do not have constraints files.
             # See https://github.com/googleapis/gapic-generator-python/issues/1788

tests/integration/goldens/redis/testing/constraints-3.9-async-rest.txt

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List all library dependencies and extras in this file,
+# pinning their versions to their lower bounds.
+# For example, if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0",
+# then this file should have google-cloud-foo==1.14.0
+google-api-core==2.21.0
+google-auth==2.35.0
+# TODO(https://github.com/googleapis/gapic-generator-python/issues/2453)
+# Add the minimum supported version of grpcio to constraints files
+proto-plus==1.22.3
+protobuf==4.25.8

tests/integration/goldens/redis_selective/testing/constraints-3.9-async-rest.txt

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List all library dependencies and extras in this file,
+# pinning their versions to their lower bounds.
+# For example, if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0",
+# then this file should have google-cloud-foo==1.14.0
+google-api-core==2.21.0
+google-auth==2.35.0
+# TODO(https://github.com/googleapis/gapic-generator-python/issues/2453)
+# Add the minimum supported version of grpcio to constraints files
+proto-plus==1.22.3
+protobuf==4.25.8