Add env() config binding with teleport() for CLI-to-worker config passing

fastapi-vue/tests/test_environ.py

@@ -0,0 +1,126 @@
+"""Tests for env() object binding and teleport()."""
+
+import dataclasses
+import json
+import os
+from collections.abc import Iterator
+
+import msgspec
+import pytest
+from fastapi_vue import env, teleport
+from fastapi_vue.environ import PREFIX_VARIABLE, _Env
+
+
+@pytest.fixture(autouse=True)
+def _clean_bindings(monkeypatch: pytest.MonkeyPatch) -> Iterator[None]:
+    env._bindings.clear()  # noqa: SLF001
+    monkeypatch.setenv(PREFIX_VARIABLE, "TEST")
+    yield
+    env._bindings.clear()  # noqa: SLF001
+
+
+class StructConfig(msgspec.Struct):
+    """msgspec struct config."""
+
+    host: str = "localhost"
+    port: int = 8000
+
+
+@dataclasses.dataclass
+class DataclassConfig:
+    """Dataclass config."""
+
+    host: str = "localhost"
+    port: int = 8000
+
+
+def test_default_construction_and_identity() -> None:
+    """Unset env: default-constructed; repeated binds return the same object."""
+    config = env(StructConfig)
+    assert config.host == "localhost"
+    assert env(StructConfig) is config
+
+
+def test_name_mangling() -> None:
+    """Class names uppercase as-is; repeated/edge underscores normalize."""
+    env(StructConfig)
+    teleport()
+    assert json.loads(os.environ["TEST_STRUCTCONFIG"])["port"] == 8000
+
+    @dataclasses.dataclass
+    class _my__config_:  # noqa: N801
+        x: int = 0
+
+    env(_my__config_)
+    teleport()
+    assert "TEST_MY_CONFIG" in os.environ
+
+
+def test_name_override() -> None:
+    """name= overrides the mangled class name verbatim."""
+    env(DataclassConfig, name="SETTINGS")
+    teleport()
+    assert "TEST_SETTINGS" in os.environ
+
+
+def test_name_conflict() -> None:
+    """A different type with a colliding env name raises KeyError."""
+    env(StructConfig)
+    with pytest.raises(KeyError, match="already bound"):
+        env(DataclassConfig, name="STRUCTCONFIG")
+
+
+def test_reserved_names() -> None:
+    """Names used by fastapi-vue itself cannot be bound, by mangle or name=."""
+    with pytest.raises(KeyError, match="reserved"):
+        env(DataclassConfig, name="DEV")
+
+    @dataclasses.dataclass
+    class Dev:
+        x: int = 0
+
+    with pytest.raises(KeyError, match="reserved"):
+        env(Dev)
+
+
+def test_unsupported_type() -> None:
+    """Only dataclasses and msgspec.Structs can be bound."""
+    with pytest.raises(TypeError, match=r"dataclass or msgspec\.Struct"):
+        env(dict)
+
+
+def test_struct_teleport_and_decode() -> None:
+    """A mutated struct teleports; a fresh registry decodes it (worker view)."""
+    config = env(StructConfig)
+    config.port = 9000
+    teleport()
+    decoded = _Env()(StructConfig)
+    assert decoded == config
+    assert decoded is not config
+
+
+def test_dataclass_teleport_and_decode() -> None:
+    """Dataclasses round-trip through the environment via stdlib json."""
+    config = env(DataclassConfig)
+    config.host = "example.com"
+    teleport()
+    assert _Env()(DataclassConfig) == config
+
+
+def test_decode_on_bind_when_set(monkeypatch: pytest.MonkeyPatch) -> None:
+    """An already-set variable is decoded at binding time."""
+    monkeypatch.setenv("TEST_STRUCTCONFIG", '{"host": "example.com", "port": 1}')
+    assert env(StructConfig).host == "example.com"
+
+
+def test_teleport_without_prefix(monkeypatch: pytest.MonkeyPatch) -> None:
+    """teleport() with bindings but no FASTAPI_VUE prefix fails loudly."""
+    monkeypatch.delenv(PREFIX_VARIABLE)
+    env(StructConfig)
+    with pytest.raises(RuntimeError, match=PREFIX_VARIABLE):
+        teleport()
+
+
+def test_teleport_noop_without_bindings() -> None:
+    """No bindings: teleport() needs no prefix and does nothing."""
+    teleport()