From 65b957a82f873199d36a80b0925b9baab1e0c4a7 Mon Sep 17 00:00:00 2001
From: Paul Natsuo Kishimoto <mail@paul.kishimoto.name>
Date: Mon, 30 Oct 2023 12:15:10 +0100
Subject: [PATCH] Test from_url()

---
 message_ix_models/report/computations.py      | 29 ++++++++-----------
 .../tests/report/test_computations.py         | 27 ++++++++++++++---
 2 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/message_ix_models/report/computations.py b/message_ix_models/report/computations.py
index 394c4109a7..20b5acfb2f 100644
--- a/message_ix_models/report/computations.py
+++ b/message_ix_models/report/computations.py
@@ -210,23 +210,18 @@ def remove_ts(
 # Non-weak references to objects to keep them alive
 _FROM_URL_REF: Set[Any] = set()
 
-# def from_url(url: str) -> message_ix.Scenario:
-#     """Return a :class:`message_ix.Scenario` given its `url`.
-#
-#     .. todo:: Move upstream to :mod:`message_ix.reporting`.
-#     .. todo:: Create a similar method in :mod:`ixmp.reporting` to load and return
-#        :class:`ixmp.TimeSeries` (or :class:`ixmp.Scenario`) given its `url`.
-#     """
-#     s, mp = message_ix.Scenario.from_url(url)
-#     assert s is not None
-#     _FROM_URL_REF.add(s)
-#     _FROM_URL_REF.add(mp)
-#     return s
-
-
-def from_url(url: str) -> ixmp.TimeSeries:
-    """Return a :class:`ixmp.TimeSeries` given its `url`."""
-    ts, mp = ixmp.TimeSeries.from_url(url)
+
+def from_url(url: str, cls=ixmp.TimeSeries) -> ixmp.TimeSeries:
+    """Return a :class:`ixmp.TimeSeries` or subclass instance, given its `url`.
+
+    .. todo:: Move upstream, to :mod:`ixmp.reporting`.
+
+    Parameters
+    ----------
+    cls : type, *optional*
+        Subclass to instantiate and return; for instance, |Scenario|.
+    """
+    ts, mp = cls.from_url(url)
     assert ts is not None
     _FROM_URL_REF.add(ts)
     _FROM_URL_REF.add(mp)
diff --git a/message_ix_models/tests/report/test_computations.py b/message_ix_models/tests/report/test_computations.py
index ed71e2a3b3..2c7b4544e7 100644
--- a/message_ix_models/tests/report/test_computations.py
+++ b/message_ix_models/tests/report/test_computations.py
@@ -1,9 +1,12 @@
 import re
 
+import ixmp
+import message_ix
 import pandas as pd
 import pytest
 import xarray as xr
 from genno import Computer, Quantity
+from message_ix.testing import make_dantzig
 
 from message_ix_models import ScenarioInfo
 from message_ix_models.model.structure import get_codes
@@ -25,6 +28,12 @@ def c() -> Computer:
     return Computer()
 
 
+@pytest.fixture
+def scenario(test_context):
+    mp = test_context.get_platform()
+    yield make_dantzig(mp)
+
+
 def test_compound_growth():
     """:func:`.compound_growth` on a 2-D quantity."""
     qty = Quantity(
@@ -65,12 +74,22 @@ def test_filter_ts():
     assert {"ar"} == set(result.variable.unique())
 
 
-@pytest.mark.xfail(reason="Incomplete")
-def test_from_url():
-    from_url()
+def test_from_url(scenario):
+    full_url = f"ixmp://{scenario.platform.name}/{scenario.url}"
+
+    # Operator runs
+    result = from_url(full_url)
+    # Result is of the default class
+    assert result.__class__ is ixmp.TimeSeries
+    # Same object was retrieved
+    assert scenario.url == result.url
+
+    # Same, but specifying message_ix.Scenario
+    result = from_url(full_url, message_ix.Scenario)
+    assert result.__class__ is message_ix.Scenario
+    assert scenario.url == result.url
 
 
-@pytest.mark.xfail(reason="Incomplete")
 def test_get_ts():
     get_ts()