fix: persist google oauth pkce for headless auth

Store the pending OAuth state and code verifier between --auth-url and --auth-code so the manual headless flow can reuse Flow.fetch_token() without disabling PKCE.

tests/skills/test_google_oauth_setup.py

@@ -0,0 +1,203 @@
+"""Regression tests for Google Workspace OAuth setup.
+
+These tests cover the headless/manual auth-code flow where the browser step and
+code exchange happen in separate process invocations.
+"""
+
+import importlib.util
+import json
+import sys
+import types
+from pathlib import Path
+
+import pytest
+
+
+SCRIPT_PATH = (
+    Path(__file__).resolve().parents[2]
+    / "skills/productivity/google-workspace/scripts/setup.py"
+)
+
+
+class FakeCredentials:
+    def __init__(self, payload=None):
+        self._payload = payload or {
+            "token": "access-token",
+            "refresh_token": "refresh-token",
+            "token_uri": "https://oauth2.googleapis.com/token",
+            "client_id": "client-id",
+            "client_secret": "client-secret",
+            "scopes": ["scope-a"],
+        }
+
+    def to_json(self):
+        return json.dumps(self._payload)
+
+
+class FakeFlow:
+    created = []
+    default_state = "generated-state"
+    default_verifier = "generated-code-verifier"
+    credentials_payload = None
+    fetch_error = None
+
+    def __init__(
+        self,
+        client_secrets_file,
+        scopes,
+        *,
+        redirect_uri=None,
+        state=None,
+        code_verifier=None,
+        autogenerate_code_verifier=False,
+    ):
+        self.client_secrets_file = client_secrets_file
+        self.scopes = scopes
+        self.redirect_uri = redirect_uri
+        self.state = state
+        self.code_verifier = code_verifier
+        self.autogenerate_code_verifier = autogenerate_code_verifier
+        self.authorization_kwargs = None
+        self.fetch_token_calls = []
+        self.credentials = FakeCredentials(self.credentials_payload)
+
+        if autogenerate_code_verifier and not self.code_verifier:
+            self.code_verifier = self.default_verifier
+        if not self.state:
+            self.state = self.default_state
+
+    @classmethod
+    def reset(cls):
+        cls.created = []
+        cls.default_state = "generated-state"
+        cls.default_verifier = "generated-code-verifier"
+        cls.credentials_payload = None
+        cls.fetch_error = None
+
+    @classmethod
+    def from_client_secrets_file(cls, client_secrets_file, scopes, **kwargs):
+        inst = cls(client_secrets_file, scopes, **kwargs)
+        cls.created.append(inst)
+        return inst
+
+    def authorization_url(self, **kwargs):
+        self.authorization_kwargs = kwargs
+        return f"https://auth.example/authorize?state={self.state}", self.state
+
+    def fetch_token(self, **kwargs):
+        self.fetch_token_calls.append(kwargs)
+        if self.fetch_error:
+            raise self.fetch_error
+
+
+@pytest.fixture
+def setup_module(monkeypatch, tmp_path):
+    FakeFlow.reset()
+
+    google_auth_module = types.ModuleType("google_auth_oauthlib")
+    flow_module = types.ModuleType("google_auth_oauthlib.flow")
+    flow_module.Flow = FakeFlow
+    google_auth_module.flow = flow_module
+    monkeypatch.setitem(sys.modules, "google_auth_oauthlib", google_auth_module)
+    monkeypatch.setitem(sys.modules, "google_auth_oauthlib.flow", flow_module)
+
+    spec = importlib.util.spec_from_file_location("google_workspace_setup_test", SCRIPT_PATH)
+    module = importlib.util.module_from_spec(spec)
+    assert spec.loader is not None
+    spec.loader.exec_module(module)
+
+    monkeypatch.setattr(module, "_ensure_deps", lambda: None)
+    monkeypatch.setattr(module, "CLIENT_SECRET_PATH", tmp_path / "google_client_secret.json")
+    monkeypatch.setattr(module, "TOKEN_PATH", tmp_path / "google_token.json")
+    monkeypatch.setattr(module, "PENDING_AUTH_PATH", tmp_path / "google_oauth_pending.json", raising=False)
+
+    client_secret = {
+        "installed": {
+            "client_id": "client-id",
+            "client_secret": "client-secret",
+            "auth_uri": "https://accounts.google.com/o/oauth2/auth",
+            "token_uri": "https://oauth2.googleapis.com/token",
+        }
+    }
+    module.CLIENT_SECRET_PATH.write_text(json.dumps(client_secret))
+    return module
+
+
+class TestGetAuthUrl:
+    def test_persists_state_and_code_verifier_for_later_exchange(self, setup_module, capsys):
+        setup_module.get_auth_url()
+
+        out = capsys.readouterr().out.strip()
+        assert out == "https://auth.example/authorize?state=generated-state"
+
+        saved = json.loads(setup_module.PENDING_AUTH_PATH.read_text())
+        assert saved["state"] == "generated-state"
+        assert saved["code_verifier"] == "generated-code-verifier"
+
+        flow = FakeFlow.created[-1]
+        assert flow.autogenerate_code_verifier is True
+        assert flow.authorization_kwargs == {"access_type": "offline", "prompt": "consent"}
+
+
+class TestExchangeAuthCode:
+    def test_reuses_saved_pkce_material_for_plain_code(self, setup_module):
+        setup_module.PENDING_AUTH_PATH.write_text(
+            json.dumps({"state": "saved-state", "code_verifier": "saved-verifier"})
+        )
+
+        setup_module.exchange_auth_code("4/test-auth-code")
+
+        flow = FakeFlow.created[-1]
+        assert flow.state == "saved-state"
+        assert flow.code_verifier == "saved-verifier"
+        assert flow.fetch_token_calls == [{"code": "4/test-auth-code"}]
+        assert json.loads(setup_module.TOKEN_PATH.read_text())["token"] == "access-token"
+        assert not setup_module.PENDING_AUTH_PATH.exists()
+
+    def test_extracts_code_from_redirect_url_and_checks_state(self, setup_module):
+        setup_module.PENDING_AUTH_PATH.write_text(
+            json.dumps({"state": "saved-state", "code_verifier": "saved-verifier"})
+        )
+
+        setup_module.exchange_auth_code(
+            "http://localhost:1/?code=4/extracted-code&state=saved-state&scope=gmail"
+        )
+
+        flow = FakeFlow.created[-1]
+        assert flow.fetch_token_calls == [{"code": "4/extracted-code"}]
+
+    def test_rejects_state_mismatch(self, setup_module, capsys):
+        setup_module.PENDING_AUTH_PATH.write_text(
+            json.dumps({"state": "saved-state", "code_verifier": "saved-verifier"})
+        )
+
+        with pytest.raises(SystemExit):
+            setup_module.exchange_auth_code(
+                "http://localhost:1/?code=4/extracted-code&state=wrong-state"
+            )
+
+        out = capsys.readouterr().out
+        assert "state mismatch" in out.lower()
+        assert not setup_module.TOKEN_PATH.exists()
+
+    def test_requires_pending_auth_session(self, setup_module, capsys):
+        with pytest.raises(SystemExit):
+            setup_module.exchange_auth_code("4/test-auth-code")
+
+        out = capsys.readouterr().out
+        assert "run --auth-url first" in out.lower()
+        assert not setup_module.TOKEN_PATH.exists()
+
+    def test_keeps_pending_auth_session_when_exchange_fails(self, setup_module, capsys):
+        setup_module.PENDING_AUTH_PATH.write_text(
+            json.dumps({"state": "saved-state", "code_verifier": "saved-verifier"})
+        )
+        FakeFlow.fetch_error = Exception("invalid_grant: Missing code verifier")
+
+        with pytest.raises(SystemExit):
+            setup_module.exchange_auth_code("4/test-auth-code")
+
+        out = capsys.readouterr().out
+        assert "token exchange failed" in out.lower()
+        assert setup_module.PENDING_AUTH_PATH.exists()
+        assert not setup_module.TOKEN_PATH.exists()