feat(tox): Add -latest alias for each integration test suite

For every auto-generated integration, add a tox environment that aliases
the highest tested version. E.g. `tox -e py3.14-httpx-latest` is
equivalent to `tox -e py3.14-httpx-v0.28.1`.

This makes it easy to run the latest version's tests without having to
look up the exact version string.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sentrivana

scripts/populate_tox/populate_tox.py

@@ -724,6 +724,31 @@ def _render_dependencies(integration: str, releases: list[Version]) -> list[str]
     return rendered
 
 
+def _render_latest_dependencies(
+    integration: str, latest_release: Version
+) -> list[str]:
+    """Render version-specific dependencies for the 'latest' alias.
+
+    Dependencies with "*" or "py3.*" constraints already match the latest
+    env via tox factor matching, so only version-specific constraints need
+    to be duplicated here.
+    """
+    rendered = []
+
+    if TEST_SUITE_CONFIG[integration].get("deps") is None:
+        return rendered
+
+    for constraint, deps in TEST_SUITE_CONFIG[integration]["deps"].items():
+        if constraint == "*" or constraint.startswith("py3"):
+            continue
+        restriction = SpecifierSet(constraint, prereleases=True)
+        if latest_release in restriction:
+            for dep in deps:
+                rendered.append(f"{integration}-latest: {dep}")
+
+    return rendered
+
+
 def write_tox_file(packages: dict) -> None:
     template = ENV.get_template("tox.jinja")
 
@@ -744,6 +769,9 @@ def write_tox_file(packages: dict) -> None:
                     "dependencies": _render_dependencies(
                         integration["name"], integration["releases"]
                     ),
+                    "latest_dependencies": _render_latest_dependencies(
+                        integration["name"], integration["releases"][-1]
+                    ),
                 }
             )
             context["testpaths"].append(

scripts/populate_tox/tox.jinja

@@ -61,6 +61,7 @@ envlist =
     {% for release in integration.releases %}
     {{ release.rendered_python_versions }}-{{ integration.name }}-v{{ release }}
     {% endfor %}
+    {{ integration.releases[-1].rendered_python_versions }}-{{ integration.name }}-latest
 
     {% endfor %}
 
@@ -143,9 +144,17 @@ deps =
     {{ integration.name }}-v{{ release }}: {{ integration.package }}=={{ release }}
     {% endif %}
     {% endfor %}
+    {% if integration.extra %}
+    {{ integration.name }}-latest: {{ integration.package }}[{{ integration.extra }}]=={{ integration.releases[-1] }}
+    {% else %}
+    {{ integration.name }}-latest: {{ integration.package }}=={{ integration.releases[-1] }}
+    {% endif %}
     {% for dep in integration.dependencies %}
     {{ dep }}
     {% endfor %}
+    {% for dep in integration.latest_dependencies %}
+    {{ dep }}
+    {% endfor %}
 
     {% endfor %}
 

scripts/split_tox_gh_actions/split_tox_gh_actions.py

@@ -240,6 +240,11 @@ def parse_tox():
             raw_python_versions = groups["py_versions"]
             framework = groups["framework"]
 
+            # The -latest env is an alias for the highest version of the
+            # same framework, so merge it with the base framework.
+            if framework.endswith("-latest"):
+                framework = framework[: -len("-latest")]
+
             # collect python versions to test the framework in
             raw_python_versions = set(raw_python_versions.split(","))
             py_versions[framework] |= raw_python_versions