feat: throw on typegen with no registered namespaces

polugins/pyproject.toml

@@ -14,7 +14,7 @@ tomli = ">=0.2.0"
 
 [tool.poetry.group.dev.dependencies]
 example-package = {path = "tests/pkgs/example_package"}
-ruff = "0.1.6"
+ruff = "0.1.11"
 nox = "^2023.4.22"
 pytest = "^7.3.1"
 pytest-env = "^0.8.2"

polugins_type_gen/pyproject.toml

@@ -17,12 +17,13 @@ optional = true
 polugins = ">=0.2" # We use it for the scripts/generate_polars_stubs.py
 pytest = "^7.3.1"
 mypy = "1.7.1" # Not sure it's considered Public API what we import, so we fix the version.
-ruff = "0.1.6"
+ruff = "0.1.11"
 nox = "^2023.4.22"
 coverage = "^7.2.7"
 pytest-env = "^0.8.2"
 pytest-cov = "^4.1.0"
 example-package = {path = "tests/pkgs/example_package"}
+pytest-mock = "^3.12.0"
 
 [tool.poetry.group.nox]
 optional = true

polugins_type_gen/src/polugins_type_gen/cli.py

@@ -6,6 +6,14 @@
 from polugins.main import _get_namespaces
 
 
+class MissingVersionException(Exception):
+    pass
+
+
+class NoNamespaceRegisteredException(Exception):
+    pass
+
+
 def has_version(version: str) -> bool:
     files = importlib_resources.files("polugins_type_gen")
     return (files / "_stubs" / version).is_dir()
@@ -19,10 +27,18 @@ def create_stubs(version: str):
             " This is usually because the version has been yanked or because it's new."
             " Feel free to create an issue if you want types for this version."
         )
-        raise ValueError(msg)
+        raise MissingVersionException(msg)
 
     all_namespaces = _get_namespaces()
 
+    if all(namespace == {} for namespace in all_namespaces.values()):
+        msg = (
+            "No namespaces found. No types will be generated as this is usually an error."
+            " Note that only namespaces registered through config, env vars or endpoints"
+            " can have types genered for them."
+        )
+        raise NoNamespaceRegisteredException(msg)
+
     for extension_class, namespaces in all_namespaces.items():
         if namespaces:
             files = importlib_resources.files("polugins_type_gen")

polugins_type_gen/tests/test_cli.py

@@ -4,7 +4,11 @@
 import pytest
 from polugins._types import ExtensionClass
 
-from polugins_type_gen.cli import create_stubs
+from polugins_type_gen.cli import (
+    MissingVersionException,
+    NoNamespaceRegisteredException,
+    create_stubs,
+)
 
 typings_dir = Path("typings")
 
@@ -19,10 +23,29 @@ def typings_directory():
 
 
 def test_cli(typings_directory):
-    create_stubs("0.19.13")
+    create_stubs("0.20.3")
     lazyframe_stubs_path = (typings_dir / ExtensionClass.LAZYFRAME.import_path).with_suffix(".pyi")
     lazyframe_stubs = lazyframe_stubs_path.read_text()
     assert "external: example_package.PackageNamespace" in lazyframe_stubs
     assert "pyproject: polugins._testing.namespaces.PyProjectNameSpace" in lazyframe_stubs
     assert "config: polugins._testing.namespaces.ConfigNameSpace" in lazyframe_stubs
     assert "env: polugins._testing.namespaces.EnvNameSpace" in lazyframe_stubs
+
+
+def test_exception_on_no_namespaces(mocker):
+    mocker.patch(
+        "polugins_type_gen.cli._get_namespaces",
+        return_value={
+            ExtensionClass.EXPR: {},
+            ExtensionClass.SERIES: {},
+            ExtensionClass.LAZYFRAME: {},
+            ExtensionClass.DATAFRAME: {},
+        },
+    )
+    with pytest.raises(NoNamespaceRegisteredException):
+        create_stubs("0.20.3")
+
+
+def test_exception_on_non_existing_version():
+    with pytest.raises(MissingVersionException):
+        create_stubs("9999.99.9")