Nest config flow (#14921)

* Move nest to dir based component

* Add config flow for Nest

* Load Nest platforms via config entry

* Add tests for Nest config flow

* Import existing access tokens as config entries

* Lint

* Update coverage

* Update translation

* Fix tests

* Address strings

* Use python-nest token resolution

* Lint

* Do not do I/O inside constructor

* Lint

* Update test requirements

tests/components/nest/test_local_auth.py

@@ -0,0 +1,51 @@
+"""Test Nest local auth."""
+from homeassistant.components.nest import const, config_flow, local_auth
+from urllib.parse import parse_qsl
+
+import pytest
+
+import requests_mock as rmock
+
+
+@pytest.fixture
+def registered_flow(hass):
+    """Mock a registered flow."""
+    local_auth.initialize(hass, 'TEST-CLIENT-ID', 'TEST-CLIENT-SECRET')
+    return hass.data[config_flow.DATA_FLOW_IMPL][const.DOMAIN]
+
+
+async def test_generate_auth_url(registered_flow):
+    """Test generating an auth url.
+
+    Mainly testing that it doesn't blow up.
+    """
+    url = await registered_flow['gen_authorize_url']('TEST-FLOW-ID')
+    assert url is not None
+
+
+async def test_convert_code(requests_mock, registered_flow):
+    """Test converting a code."""
+    from nest.nest import ACCESS_TOKEN_URL
+
+    def token_matcher(request):
+        """Match a fetch token request."""
+        if request.url != ACCESS_TOKEN_URL:
+            return None
+
+        assert dict(parse_qsl(request.text)) == {
+            'client_id': 'TEST-CLIENT-ID',
+            'client_secret': 'TEST-CLIENT-SECRET',
+            'code': 'TEST-CODE',
+            'grant_type': 'authorization_code'
+        }
+
+        return rmock.create_response(request, json={
+            'access_token': 'TEST-ACCESS-TOKEN'
+        })
+
+    requests_mock.add_matcher(token_matcher)
+
+    tokens = await registered_flow['convert_code']('TEST-CODE')
+    assert tokens == {
+        'access_token': 'TEST-ACCESS-TOKEN'
+    }