Split test_spectrum.py (#2151)

* Split test_spectrum.py files

Restructure tests in line with mismatch.py restructure (#2136)

* fix conftest import

* Update test_mismatch.py

add spectrl2_data function to mismatch.py

* Update v0.11.1.rst

* create pvlib\tests\spectrum\conftest.py

Author: RDaxini

docs/sphinx/source/whatsnew/v0.11.1.rst

@@ -19,7 +19,7 @@ Enhancements
 * Restructured the pvlib/spectrum folder by breaking up the contents of
   pvlib/spectrum/mismatch.py into pvlib/spectrum/mismatch.py,
   pvlib/spectrum/irradiance.py, and
-  pvlib/spectrum/response.py. (:issue:`2125`, :pull:`2136`)
+  pvlib/spectrum/response.py. (:issue:`2125`, :pull:`2136`, :pull:`2151`)
 * Added function for calculating wind speed at different heights,
   :py:func:`pvlib.atmosphere.windspeed_powerlaw`.
   (:issue:`2118`, :pull:`2124`)

pvlib/tests/spectrum/__init__.py

@@ -0,0 +1,40 @@
+import numpy as np
+import pytest
+import pandas as pd
+
+from ..conftest import DATA_DIR
+
+SPECTRL2_TEST_DATA = DATA_DIR / 'spectrl2_example_spectra.csv'
+
+
+@pytest.fixture
+def spectrl2_data():
+    # reference spectra generated with solar_utils==0.3
+    """
+    expected = solar_utils.spectrl2(
+        units=1,
+        location=[40, -80, -5],
+        datetime=[2020, 3, 15, 10, 45, 59],
+        weather=[1013, 15],
+        orientation=[0, 180],
+        atmospheric_conditions=[1.14, 0.65, 0.344, 0.1, 1.42],
+        albedo=[0.3, 0.7, 0.8, 1.3, 2.5, 4.0] + [0.2]*6,
+    )
+    """
+    kwargs = {
+        'surface_tilt': 0,
+        'relative_airmass': 1.4899535986910446,
+        'apparent_zenith': 47.912086486816406,
+        'aoi': 47.91208648681641,
+        'ground_albedo': 0.2,
+        'surface_pressure': 101300,
+        'ozone': 0.344,
+        'precipitable_water': 1.42,
+        'aerosol_turbidity_500nm': 0.1,
+        'dayofyear': 75
+    }
+    df = pd.read_csv(SPECTRL2_TEST_DATA, index_col=0)
+    # convert um to nm
+    df['wavelength'] = np.round(df['wavelength'] * 1000, 1)
+    df[['specdif', 'specdir', 'specetr', 'specglo']] /= 1000
+    return kwargs, df

pvlib/tests/spectrum/conftest.py

@@ -0,0 +1,74 @@
+import pytest
+from numpy.testing import assert_allclose, assert_approx_equal, assert_equal
+import pandas as pd
+import numpy as np
+from pvlib import spectrum
+from pvlib._deprecation import pvlibDeprecationWarning
+
+from ..conftest import assert_series_equal, fail_on_pvlib_version
+
+
+@fail_on_pvlib_version('0.12')
+def test_get_am15g():
+    # test that the reference spectrum is read and interpolated correctly
+    with pytest.warns(pvlibDeprecationWarning,
+                      match="get_reference_spectra instead"):
+        e = spectrum.get_am15g()
+    assert_equal(len(e), 2002)
+    assert_equal(np.sum(e.index), 2761442)
+    assert_approx_equal(np.sum(e), 1002.88, significant=6)
+
+    wavelength = [270, 850, 950, 1200, 1201.25, 4001]
+    expected = [0.0, 0.893720, 0.147260, 0.448250, 0.4371025, 0.0]
+
+    with pytest.warns(pvlibDeprecationWarning,
+                      match="get_reference_spectra instead"):
+        e = spectrum.get_am15g(wavelength)
+    assert_equal(len(e), len(wavelength))
+    assert_allclose(e, expected, rtol=1e-6)
+
+
+@pytest.mark.parametrize(
+    "reference_identifier,expected_sums",
+    [
+        (
+            "ASTM G173-03",  # reference_identifier
+            {  # expected_sums
+                "extraterrestrial": 1356.15,
+                "global": 1002.88,
+                "direct": 887.65,
+            },
+        ),
+    ],
+)
+def test_get_reference_spectra(reference_identifier, expected_sums):
+    # test reading of a standard spectrum
+    standard = spectrum.get_reference_spectra(standard=reference_identifier)
+    assert set(standard.columns) == expected_sums.keys()
+    assert standard.index.name == "wavelength"
+    assert standard.index.is_monotonic_increasing is True
+    expected_sums = pd.Series(expected_sums)  # convert prior to comparison
+    assert_series_equal(np.sum(standard, axis=0), expected_sums, atol=1e-2)
+
+
+def test_get_reference_spectra_custom_wavelengths():
+    # test that the spectrum is interpolated correctly when custom wavelengths
+    # are specified
+    # only checked for ASTM G173-03 reference spectrum
+    wavelength = [270, 850, 951.634, 1200, 4001]
+    expected_sums = pd.Series(
+        {"extraterrestrial": 2.23266, "global": 1.68952, "direct": 1.58480}
+    )  # for given ``wavelength``
+    standard = spectrum.get_reference_spectra(
+        wavelength, standard="ASTM G173-03"
+    )
+    assert_equal(len(standard), len(wavelength))
+    # check no NaN values were returned
+    assert not standard.isna().any().any()  # double any to return one value
+    assert_series_equal(np.sum(standard, axis=0), expected_sums, atol=1e-4)
+
+
+def test_get_reference_spectra_invalid_reference():
+    # test that an invalid reference identifier raises a ValueError
+    with pytest.raises(ValueError, match="Invalid standard identifier"):
+        spectrum.get_reference_spectra(standard="invalid")