MNT: address Meteomatics review comments

Two points raised in the PR review:

- `fetch_atmospheric_data_from_meteomatics` stamped the instant with a
  trailing "Z" without normalizing the timezone, so an aware datetime in
  a non-UTC zone was sent as the wrong instant. Aware datetimes are now
  converted to UTC; naive ones are documented as assumed UTC.
- Degenerate sampling arguments (`query_limit=0`, resolutions below 2)
  reached `range()`/`linspace()` and failed with an opaque low-level
  error after the login had already been paid for. They are now
  validated up front by `_validate_meteomatics_sampling`.
- `process_meteomatics_atmosphere` silently coerced any non-string model
  to "mix", hiding a mistake such as passing a Dataset or a path as
  `file` and querying the wrong model. It now accepts None (default) or
  a string, and raises otherwise.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Gui-FernandesBR

rocketpy/environment/environment.py

@@ -1808,10 +1808,18 @@ def process_meteomatics_atmosphere(  # pylint: disable=too-many-statements
         Raises
         ------
         ValueError
-            If credentials are missing, if no launch date is set, or if the API
-            returns no usable data.
+            If ``model`` is not a string, if credentials are missing, if no
+            launch date is set, or if the API returns no usable data.
         """
-        model = model or "mix"
+        if model is None:
+            model = "mix"
+        elif not isinstance(model, str):
+            # Coercing silently would hide a mistake such as passing a Dataset
+            # or a file path as 'file', and would query the wrong model.
+            raise ValueError(
+                f"Invalid Meteomatics model {model!r}: expected the model name as "
+                "a string (e.g. 'mix'), or None to use the default."
+            )
         username = username or os.environ.get("METEOMATICS_USERNAME")
         password = password or os.environ.get("METEOMATICS_PASSWORD")
         if not username or not password:

rocketpy/environment/fetchers.py

@@ -617,6 +617,39 @@ def levels(resolution):
     }
 
 
+def _validate_meteomatics_sampling(
+    min_altitude,
+    max_altitude,
+    wind_resolution,
+    temperature_pressure_resolution,
+    query_limit,
+):
+    """Validates the sampling arguments before any request is issued.
+
+    Catching these here keeps a degenerate input from reaching ``linspace`` or
+    ``range``, where it would surface as an opaque low-level error (or as an
+    empty request) after the account has already been charged for the login.
+
+    Raises
+    ------
+    ValueError
+        If the altitude range, the resolutions or the query limit are invalid.
+    """
+    if min_altitude < 0:
+        raise ValueError(
+            "min_altitude must be non-negative (heights are above ground level)."
+        )
+    if max_altitude <= min_altitude:
+        raise ValueError("max_altitude must be greater than min_altitude.")
+    if wind_resolution < 2 or temperature_pressure_resolution < 2:
+        raise ValueError(
+            "wind_resolution and temperature_pressure_resolution must be at least "
+            "2: a single altitude level is not enough to define a profile."
+        )
+    if query_limit < 1:
+        raise ValueError("query_limit must be at least 1.")
+
+
 def _extract_meteomatics_json(data):
     """Extracts (parameter, value) pairs from a Meteomatics JSON response.
 
@@ -682,7 +715,9 @@ def fetch_atmospheric_data_from_meteomatics(
         Longitude of the launch site, in degrees.
     date : datetime.datetime
         The instant to query. It is formatted according to the Meteomatics
-        date-time specification (``%Y-%m-%dT%H:%M:%SZ``).
+        date-time specification (``%Y-%m-%dT%H:%M:%SZ``). Timezone-aware
+        datetimes are converted to UTC; naive ones are assumed to be UTC
+        already.
     model : str, optional
         The Meteomatics weather model to use. Default is ``"mix"``. Your
         account may not have access to every model. See
@@ -717,18 +752,24 @@ def fetch_atmospheric_data_from_meteomatics(
         If authentication fails, the API cannot be reached, returns an error
         status, or returns a malformed response.
     ValueError
-        If the altitude range is invalid or the response contains an
-        unrecognized parameter.
+        If the altitude range, the resolutions or the query limit are invalid,
+        or if the response contains an unrecognized parameter.
     """
-    if min_altitude < 0:
-        raise ValueError(
-            "min_altitude must be non-negative (heights are above ground level)."
-        )
-    if max_altitude <= min_altitude:
-        raise ValueError("max_altitude must be greater than min_altitude.")
+    _validate_meteomatics_sampling(
+        min_altitude,
+        max_altitude,
+        wind_resolution,
+        temperature_pressure_resolution,
+        query_limit,
+    )
 
     token = fetch_meteomatics_token(username, password)
 
+    # The instant is sent with a trailing "Z", so an aware datetime must be
+    # converted to UTC instead of being formatted as-is. A naive datetime is
+    # assumed to already be in UTC.
+    if date.tzinfo is not None:
+        date = date.astimezone(timezone.utc)
     date_string = date.strftime("%Y-%m-%dT%H:%M:%SZ")
     parameter_map = _build_meteomatics_parameters(
         min_altitude, max_altitude, wind_resolution, temperature_pressure_resolution

tests/unit/environment/test_environment.py

@@ -481,6 +481,20 @@ def test_meteomatics_atmosphere_sets_profiles(example_euroc_env, monkeypatch):
     assert recorder["model"] == "mix"
 
 
+def test_meteomatics_non_string_model_raises(example_euroc_env, monkeypatch):
+    """Reject a non-string model instead of silently querying the default.
+
+    Passing a Dataset or a path as ``file`` by accident must not be coerced to
+    ``"mix"``, which would quietly query (and charge for) the wrong model.
+    """
+    _patch_meteomatics_fetcher(monkeypatch)
+
+    with pytest.raises(ValueError, match="Invalid Meteomatics model"):
+        example_euroc_env.set_atmospheric_model(
+            type="Meteomatics", file=123, username="user", password="pass"
+        )
+
+
 def test_meteomatics_reads_credentials_from_environment(example_euroc_env, monkeypatch):
     """Fall back to the METEOMATICS_* environment variables for credentials."""
     recorder = {}

tests/unit/environment/test_fetchers.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timezone
+from datetime import datetime, timedelta, timezone
 
 import pytest
 
@@ -301,3 +301,52 @@ def test_fetch_meteomatics_data_invalid_altitude_range_raises(altitudes):
             date=datetime(2024, 1, 1, 12, tzinfo=timezone.utc),
             **altitudes,
         )
+
+
+@pytest.mark.parametrize(
+    ("kwargs", "message"),
+    [
+        ({"wind_resolution": 1}, "at least"),
+        ({"temperature_pressure_resolution": 0}, "at least"),
+        ({"query_limit": 0}, "query_limit must be at least 1"),
+    ],
+)
+def test_fetch_meteomatics_data_invalid_sampling_raises(kwargs, message):
+    """Reject degenerate resolutions and query limits with a clear message.
+
+    Without the up-front check these reach ``linspace``/``range`` and fail with
+    an opaque low-level error (or an empty request) instead.
+    """
+    with pytest.raises(ValueError, match=message):
+        fetchers.fetch_atmospheric_data_from_meteomatics(
+            username="user",
+            password="pass",
+            latitude=39.0,
+            longitude=-8.0,
+            date=datetime(2024, 1, 1, 12, tzinfo=timezone.utc),
+            **kwargs,
+        )
+
+
+def test_fetch_meteomatics_data_converts_date_to_utc(monkeypatch):
+    """A non-UTC aware datetime must be converted, not stamped with a bare Z.
+
+    The request path carries the instant with a trailing "Z", so 12:00 at
+    UTC+03:00 has to be sent as 09:00Z.
+    """
+    calls = []
+    monkeypatch.setattr(fetchers.requests, "get", _make_fake_meteomatics_get(calls))
+
+    fetchers.fetch_atmospheric_data_from_meteomatics(
+        username="user",
+        password="pass",
+        latitude=39.0,
+        longitude=-8.0,
+        date=datetime(2024, 1, 1, 12, tzinfo=timezone(timedelta(hours=3))),
+        wind_resolution=2,
+        temperature_pressure_resolution=2,
+    )
+
+    data_calls = [c for c in calls if c[0] != fetchers.METEOMATICS_LOGIN_URL]
+    assert data_calls, "expected at least one data request"
+    assert all("2024-01-01T09:00:00Z" in url for url, _ in data_calls)