fix: warn when frozen Python violates project requirement

rsconnect/environment.py

@@ -160,6 +160,11 @@ def create_python_environment(
         )
         environment.python_version_requirement = python_version_requirement
 
+        if environment.source == "pip_freeze":
+            mismatch = pyproject.local_python_mismatch(python_version_requirement, environment.python)
+            if mismatch:
+                warn_user(mismatch)
+
         if override_python_version and override_python_version.count(".") == 2:
             # Retaing backward compatibility with old Connect versions
             # that didn't support environment.python.requires

rsconnect/preflight.py

@@ -24,6 +24,7 @@
     TOMLDecodeError,
     detect_python_version_requirement,
     get_python_version_requirement_parser,
+    local_python_mismatch,
     lookup_metadata_file,
 )
 
@@ -484,20 +485,6 @@ def _unknown_advice(
         actions.append("Check the project's Python metadata and server availability before publishing.")
 
 
-def _warn_local_python_mismatch(constraint: Optional[str], local_python: str, warnings: list[str]) -> None:
-    if constraint is None:
-        return
-    try:
-        matches_local = SpecifierSet(constraint).contains(local_python)
-    except (InvalidSpecifier, TypeError):
-        return
-    if not matches_local:
-        warnings.append(
-            f"Local Python {local_python} does not satisfy the project requirement {constraint}; "
-            "dependency compatibility has not been tested."
-        )
-
-
 def _local_python_version(project_dir: str, python: Optional[str]) -> str:
     interpreter = which_python(python, project_dir)
     if interpreter == sys.executable:
@@ -541,7 +528,9 @@ def _python_project_metadata(
     project_dir = str(target_path.parent) if target_path.is_file() else target
     local_python = _local_python_version(project_dir, python)
     constraint, invalid_metadata = _project_constraint(project_dir, warnings)
-    _warn_local_python_mismatch(constraint, local_python, warnings)
+    mismatch = local_python_mismatch(constraint, local_python)
+    if mismatch:
+        warnings.append(mismatch)
     return project_dir, local_python, constraint, invalid_metadata
 
 

rsconnect/pyproject.py

@@ -12,6 +12,9 @@
 import typing
 from collections.abc import Mapping
 
+from packaging.specifiers import InvalidSpecifier, SpecifierSet
+from packaging.version import InvalidVersion
+
 from .log import logger
 from .models import AppMode, AppModes
 
@@ -31,6 +34,20 @@
 VALID_VERSION_REQ_REGEX = rf"^({PEP440_OPERATORS_REGEX}?\d+(\.[\d\*]+)*)+$"
 
 
+def local_python_mismatch(constraint: typing.Optional[str], version: str) -> typing.Optional[str]:
+    if constraint is None:
+        return None
+    try:
+        if SpecifierSet(constraint).contains(version):
+            return None
+    except (InvalidSpecifier, InvalidVersion, TypeError):
+        return None
+    return (
+        f"Local Python {version} does not satisfy the project requirement {constraint}; "
+        "dependency compatibility has not been tested."
+    )
+
+
 def detect_python_version_requirement(directory: typing.Union[str, pathlib.Path]) -> typing.Optional[str]:
     """Detect the python version requirement for a project.
 

tests/test_main.py

@@ -58,6 +58,83 @@ def test_python_option_help_does_not_require_rsconnect_in_target_environment(com
     assert "must have the rsconnect" not in result.output
 
 
+@pytest.mark.parametrize(
+    "filename,contents,requirement",
+    [
+        (".python-version", "2.7\n", "~=2.7.0"),
+        ("pyproject.toml", '[project]\nrequires-python = "<3"\n', "<3"),
+        ("setup.cfg", "[options]\npython_requires = <3\n", "<3"),
+    ],
+)
+def test_write_manifest_warns_when_frozen_python_does_not_match_project(tmp_path, filename, contents, requirement):
+    (tmp_path / "app.py").write_text("app = object()\n")
+    (tmp_path / filename).write_text(contents)
+    result = CliRunner().invoke(cli, ["write-manifest", "api", str(tmp_path), "--force-generate"])
+
+    version = ".".join(map(str, sys.version_info[:3]))
+    warning = (
+        f"Local Python {version} does not satisfy the project requirement {requirement}; "
+        "dependency compatibility has not been tested."
+    )
+    assert result.exit_code == 0, result.output
+    assert warning in result.output
+    manifest = json.loads((tmp_path / "manifest.json").read_text())
+    assert manifest["python"]["version"] == version
+    assert manifest["environment"]["python"]["requires"] == requirement
+
+
+@pytest.mark.parametrize("source", ["compatible", "file", "invalid"])
+def test_write_manifest_does_not_warn_without_a_valid_frozen_mismatch(tmp_path, source):
+    (tmp_path / "app.py").write_text("app = object()\n")
+    requirement = ">=3" if source == "compatible" else ("invalid" if source == "invalid" else "<3")
+    (tmp_path / "pyproject.toml").write_text(f'[project]\nrequires-python = "{requirement}"\n')
+    args = ["write-manifest", "api", str(tmp_path)]
+    if source == "file":
+        (tmp_path / "requirements.txt").write_text("flask\n")
+    else:
+        args.append("--force-generate")
+
+    result = CliRunner().invoke(cli, args)
+
+    assert result.exit_code == 0, result.output
+    assert "does not satisfy the project requirement" not in result.output
+
+
+def test_deploy_warns_before_server_connection_when_freezing_incompatible_python(tmp_path, monkeypatch):
+    from rsconnect.exception import RSConnectException
+
+    (tmp_path / "app.py").write_text("app = object()\n")
+    (tmp_path / ".python-version").write_text("2.7\n")
+
+    def stop_before_server_connection(*args, **kwargs):
+        raise RSConnectException("Stopped before server connection")
+
+    monkeypatch.setattr("rsconnect.main.RSConnectExecutor", stop_before_server_connection)
+    try:
+        result = CliRunner().invoke(cli, ["deploy", "api", str(tmp_path), "--force-generate", "--quiet"])
+    finally:
+        rs_logger.set_quiet(False)
+        rs_logger.setLevel(logging.INFO)
+        console_logger.setLevel(logging.DEBUG)
+
+    version = ".".join(map(str, sys.version_info[:3]))
+    assert result.exit_code != 0
+    assert "Stopped before server connection" in result.output
+    assert f"Local Python {version} does not satisfy the project requirement ~=2.7.0" in result.output
+
+
+def test_override_warns_using_frozen_python_before_manifest_version_override(tmp_path):
+    (tmp_path / "app.py").write_text("app = object()\n")
+    result = CliRunner().invoke(
+        cli, ["write-manifest", "api", str(tmp_path), "--force-generate", "--override-python-version", "2.7.1"]
+    )
+
+    version = ".".join(map(str, sys.version_info[:3]))
+    assert result.exit_code == 0, result.output
+    assert f"Local Python {version} does not satisfy the project requirement ==2.7.1" in result.output
+    assert json.loads((tmp_path / "manifest.json").read_text())["python"]["version"] == "2.7.1"
+
+
 class TestMain:
     # Every env var ``metadata.config_dirname()`` consults. ``HOME`` alone only
     # isolates macOS: Linux prefers ``XDG_CONFIG_HOME`` and Windows prefers