Allow passing the mocker in the constructor

This is to be able to call `start()` without any arguments, so we can
make the `MockMicrogrid` an async context manager, to make sure it is
properly finalized after it is used.

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

.github/labeler.yml

@@ -4,48 +4,68 @@
 # The basic syntax is [label]: [path patterns].
 #
 # For more details on the configuration please see:
+  - changed-files:
+    - any-glob-to-any-file:
 # https://github.com/marketplace/actions/labeler
 
 "part:actor":
-  - "src/frequenz/sdk/actor/**"
+  - changed-files:
+    - any-glob-to-any-file:
+      - "src/frequenz/sdk/actor/**"
 
 "part:config":
-  - "src/frequenz/sdk/config/**"
+  - changed-files:
+    - any-glob-to-any-file:
+      - "src/frequenz/sdk/config/**"
 
 "part:core":
-  - "src/frequenz/sdk/_internal/**"
+  - changed-files:
+    - any-glob-to-any-file:
+      - "src/frequenz/sdk/_internal/**"
 
 "part:data-pipeline":
-  - "src/frequenz/sdk/_data_handling/**"
-  - "src/frequenz/sdk/_data_ingestion/**"
-  - "src/frequenz/sdk/timeseries/**"
+  - changed-files:
+    - any-glob-to-any-file:
+      - "src/frequenz/sdk/_data_handling/**"
+      - "src/frequenz/sdk/_data_ingestion/**"
+      - "src/frequenz/sdk/timeseries/**"
 
 "part:docs":
-  - "**/*.md"
-  - "docs/**"
-  - "examples/**"
-  - LICENSE
+  - changed-files:
+    - any-glob-to-any-file:
+      - "**/*.md"
+      - "docs/**"
+      - "examples/**"
+      - LICENSE
 
 "part:microgrid":
-  - "src/frequenz/sdk/microgrid/**"
+  - changed-files:
+    - any-glob-to-any-file:
+      - "src/frequenz/sdk/microgrid/**"
 
 "part:power-distribution":
-  - "src/frequenz/sdk/power/**"
+  - changed-files:
+    - any-glob-to-any-file:
+      - "src/frequenz/sdk/power/**"
 
 "part:tests":
-  - "**/conftest.py"
-  - "tests/**"
+  - changed-files:
+    - any-glob-to-any-file:
+      - "**/conftest.py"
+      - "tests/**"
 
 "part:tooling":
-  - "**/*.ini"
-  - "**/*.toml"
-  - "**/*.yaml"
-  - "**/*.yml"
-  - "**/conftest.py"
-  - ".editorconfig"
-  - ".git*"
-  - ".git*/**"
-  - "docs/*.py"
-  - CODEOWNERS
-  - MANIFEST.in
-  - noxfile.py
+  - changed-files:
+    - any-glob-to-any-file:
+      - "**/*.ini"
+      - "**/*.toml"
+      - "**/*.yaml"
+      - "**/*.yml"
+      - "**/conftest.py"
+      - ".editorconfig"
+      - ".git*"
+      - ".git*/**"
+      - "docs/*.py"
+      - CODEOWNERS
+      - MANIFEST.in
+      - noxfile.py

tests/timeseries/mock_microgrid.py

@@ -62,6 +62,7 @@ def __init__(  # pylint: disable=too-many-arguments
         num_namespaces: int = 1,
         fuse: Fuse | None = Fuse(Current.from_amperes(10_000.0)),
         graph: _MicrogridComponentGraph | None = None,
+        mocker: MockerFixture | None = None,
     ):
         """Create a new instance.
 
@@ -78,10 +79,12 @@ def __init__(  # pylint: disable=too-many-arguments
             fuse: optional, the fuse to use for the grid connection.
             graph: optional, a graph of components to use instead of the default grid
                 layout. If specified, grid_meter must be None.
+            mocker: optional, a mocker to pass to the mock client and mock resampler.
 
         Raises:
             ValueError: if both grid_meter and graph are specified.
         """
+        self.mocker = mocker
         if grid_meter is not None and graph is not None:
             raise ValueError("grid_meter and graph are mutually exclusive")
 
@@ -163,9 +166,22 @@ def inverters(comp_type: InverterType) -> list[int]:
             self.meter_ids.append(self._grid_meter_id)
             self._start_meter_streaming(self._grid_meter_id)
 
-    async def start(self, mocker: MockerFixture) -> None:
+    async def start(self, mocker: MockerFixture | None = None) -> None:
         """Init the mock microgrid client and start the mock resampler."""
-        self.init_mock_client(lambda mock_client: mock_client.initialize(mocker))
+        # Return if it is already started
+        if hasattr(self, "mock_client") or hasattr(self, "mock_resampler"):
+            return
+
+        if mocker is None:
+            mocker = self.mocker
+        assert mocker is not None, "A mocker must be set at init or start time"
+
+        # This binding to a local is needed because Python uses late binding for
+        # closures and `mocker` could be bound to `None` again after the lambda is
+        # created. See:
+        # https://mypy.readthedocs.io/en/stable/common_issues.html#narrowing-and-inner-functions
+        local_mocker = mocker
+        self.init_mock_client(lambda mock_client: mock_client.initialize(local_mocker))
         self.mock_resampler = MockResampler(
             mocker,
             ResamplerConfig(timedelta(seconds=self._sample_rate_s)),