Generalize testing version comparison (#3271)

* Generalize version comparison

* Add xfail condition for old pint

* Limit xfail to appropriate scipy

pyproject.toml

@@ -102,6 +102,7 @@ markers = "xfail_dask: marks tests as expected to fail with Dask arrays"
 norecursedirs = "build docs .idea"
 doctest_optionflags = "NORMALIZE_WHITESPACE"
 mpl-results-path = "test_output"
+xfail_strict = true
 
 [tool.ruff]
 line-length = 95

src/metpy/testing.py

@@ -9,8 +9,10 @@
 """
 import contextlib
 import functools
+from importlib.metadata import requires, version
+import operator as op
+import re
 
-import matplotlib
 import numpy as np
 import numpy.testing
 from packaging.version import Version
@@ -23,37 +25,87 @@
 from .deprecation import MetpyDeprecationWarning
 from .units import units
 
-MPL_VERSION = Version(matplotlib.__version__)
 
+def version_check(version_spec):
+    """Return comparison between the active module and a requested version number.
 
-def mpl_version_before(ver):
-    """Return whether the active matplotlib is before a certain version.
+    Will also validate specification against package metadata to alert if spec is irrelevant.
 
     Parameters
     ----------
-    ver : str
-        The version string for a certain release
+    version_spec : str
+        Module version specification to validate against installed package. Must take the form
+        of `f'{module_name}{comparison_operator}{version_number}'` where `comparison_operator`
+        must be one of `['==', '=', '!=', '<', '<=', '>', '>=']`, eg `'metpy>1.0'`.
 
     Returns
     -------
-        bool : whether the current version was released before the passed in one
+        bool : Whether the installed package validates against the provided specification
     """
-    return MPL_VERSION < Version(ver)
+    comparison_operators = {
+        '==': op.eq, '=': op.eq, '!=': op.ne, '<': op.lt, '<=': op.le, '>': op.gt, '>=': op.ge,
+    }
 
+    # Match version_spec for groups of module name,
+    # comparison operator, and requested module version
+    module_name, comparison, version_number = _parse_version_spec(version_spec)
 
-def mpl_version_equal(ver):
-    """Return whether the active matplotlib is equal to a certain version.
+    # Check MetPy metadata for minimum required version of same package
+    metadata_spec = _get_metadata_spec(module_name)
+    _, _, minimum_version_number = _parse_version_spec(metadata_spec)
+
+    installed_version = Version(version(module_name))
+    specified_version = Version(version_number)
+    minimum_version = Version(minimum_version_number)
+
+    if specified_version < minimum_version:
+        raise ValueError(
+            f'Specified {version_spec} outdated according to MetPy minimum {metadata_spec}.')
+
+    try:
+        return comparison_operators[comparison](installed_version, specified_version)
+    except KeyError:
+        raise ValueError(
+            f'Comparison operator {comparison} not one of {list(comparison_operators)}.'
+        ) from None
+
+
+def _parse_version_spec(version_spec):
+    """Parse module name, comparison, and version from pip-style package spec string.
+
+    Parameters
+    ----------
+    version_spec : str
+        Package spec to parse
+
+    Returns
+    -------
+        tuple of str : Parsed specification groups of package name, comparison, and version
+
+    """
+    pattern = re.compile(r'(\w+)\s*([<>!=]+)\s*([\d.]+)')
+    match = pattern.match(version_spec)
+
+    if not match:
+        raise ValueError(f'Invalid version specification {version_spec}.'
+                         f'See version_check documentation for more information.')
+    else:
+        return match.groups()
+
+
+def _get_metadata_spec(module_name):
+    """Get package spec string for requested module from package metadata.
 
     Parameters
     ----------
-    ver : str
-        The version string for a certain release
+    module_name : str
+        Name of MetPy required package to look up
 
     Returns
     -------
-        bool : whether the current version is equal to the passed in one
+        str : Package spec string for request module
     """
-    return MPL_VERSION == Version(ver)
+    return [entry for entry in requires('metpy') if module_name.lower() in entry.lower()][0]
 
 
 def needs_module(module):

tests/calc/test_indices.py

@@ -12,7 +12,8 @@
 from metpy.calc import (bulk_shear, bunkers_storm_motion, critical_angle,
                         mean_pressure_weighted, precipitable_water, significant_tornado,
                         supercell_composite, weighted_continuous_average)
-from metpy.testing import assert_almost_equal, assert_array_almost_equal, get_upper_air_data
+from metpy.testing import (assert_almost_equal, assert_array_almost_equal, get_upper_air_data,
+                           version_check)
 from metpy.units import concatenate, units
 
 
@@ -130,15 +131,15 @@ def test_weighted_continuous_average():
     assert_almost_equal(v, 6.900543760612305 * units('m/s'), 7)
 
 
-@pytest.mark.xfail(reason='hgrecco/pint#1593')
+@pytest.mark.xfail(condition=version_check('pint<0.21'), reason='hgrecco/pint#1593')
 def test_weighted_continuous_average_temperature():
     """Test pressure-weighted mean temperature function with vertical interpolation."""
     data = get_upper_air_data(datetime(2016, 5, 22, 0), 'DDC')
     t, = weighted_continuous_average(data['pressure'],
                                      data['temperature'],
                                      height=data['height'],
                                      depth=6000 * units('meter'))
-    assert_almost_equal(t, 279.3275828240889 * units('kelvin'), 7)
+    assert_almost_equal(t, 279.07450928270185 * units('kelvin'), 7)
 
 
 def test_weighted_continuous_average_elevated():

tests/calc/test_thermo.py

@@ -8,9 +8,7 @@
 import warnings
 
 import numpy as np
-import packaging.version
 import pytest
-import scipy
 import xarray as xr
 
 from metpy.calc import (brunt_vaisala_frequency, brunt_vaisala_frequency_squared,
@@ -39,7 +37,8 @@
                         virtual_temperature, virtual_temperature_from_dewpoint,
                         wet_bulb_temperature)
 from metpy.calc.thermo import _find_append_zero_crossings
-from metpy.testing import assert_almost_equal, assert_array_almost_equal, assert_nan
+from metpy.testing import (assert_almost_equal, assert_array_almost_equal, assert_nan,
+                           version_check)
 from metpy.units import is_quantity, masked_array, units
 
 
@@ -201,8 +200,9 @@ def test_moist_lapse_starting_points(start, direction):
 @pytest.mark.xfail(platform.machine() == 'aarch64',
                    reason='ValueError is not raised on aarch64')
 @pytest.mark.xfail(platform.machine() == 'arm64', reason='ValueError is not raised on Mac M2')
-@pytest.mark.xfail(sys.platform == 'win32', reason='solve_ivp() does not error on Windows')
-@pytest.mark.xfail(packaging.version.parse(scipy.__version__) < packaging.version.parse('1.7'),
+@pytest.mark.xfail((sys.platform == 'win32') and version_check('scipy<1.11.3'),
+                   reason='solve_ivp() does not error on Windows + SciPy < 1.11.3')
+@pytest.mark.xfail(version_check('scipy<1.7'),
                    reason='solve_ivp() does not error on Scipy < 1.7')
 def test_moist_lapse_failure():
     """Test moist_lapse under conditions that cause the ODE solver to fail."""

tests/plots/test_declarative.py

@@ -20,7 +20,7 @@
 from metpy.io.metar import parse_metar_file
 from metpy.plots import (ArrowPlot, BarbPlot, ContourPlot, FilledContourPlot, ImagePlot,
                          MapPanel, PanelContainer, PlotGeometry, PlotObs, RasterPlot)
-from metpy.testing import mpl_version_before, needs_cartopy
+from metpy.testing import needs_cartopy, version_check
 from metpy.units import units
 
 
@@ -334,8 +334,9 @@ def test_declarative_contour_cam():
     return pc.figure
 
 
-@pytest.mark.mpl_image_compare(remove_text=True,
-                               tolerance=3.71 if mpl_version_before('3.8') else 0.74)
+@pytest.mark.mpl_image_compare(
+    remove_text=True,
+    tolerance=3.71 if version_check('matplotlib<3.8') else 0.74)
 @needs_cartopy
 def test_declarative_contour_options():
     """Test making a contour plot."""
@@ -428,8 +429,9 @@ def test_declarative_additional_layers_plot_options():
     return pc.figure
 
 
-@pytest.mark.mpl_image_compare(remove_text=True,
-                               tolerance=2.74 if mpl_version_before('3.8') else 1.91)
+@pytest.mark.mpl_image_compare(
+    remove_text=True,
+    tolerance=2.74 if version_check('matplotlib<3.8') else 1.91)
 @needs_cartopy
 def test_declarative_contour_convert_units():
     """Test making a contour plot."""

tests/plots/test_skewt.py

@@ -11,7 +11,7 @@
 import pytest
 
 from metpy.plots import Hodograph, SkewT
-from metpy.testing import mpl_version_before, mpl_version_equal
+from metpy.testing import version_check
 from metpy.units import units
 
 
@@ -155,8 +155,10 @@ def test_skewt_units():
     skew.ax.axvline(-10, color='orange')
 
     # On Matplotlib <= 3.6, ax[hv]line() doesn't trigger unit labels
-    assert skew.ax.get_xlabel() == ('degree_Celsius' if mpl_version_equal('3.7.0') else '')
-    assert skew.ax.get_ylabel() == ('hectopascal' if mpl_version_equal('3.7.0') else '')
+    assert skew.ax.get_xlabel() == (
+        'degree_Celsius' if version_check('matplotlib==3.7.0') else '')
+    assert skew.ax.get_ylabel() == (
+        'hectopascal' if version_check('matplotlib==3.7.0') else '')
 
     # Clear them for the image test
     skew.ax.set_xlabel('')
@@ -318,8 +320,8 @@ def test_hodograph_api():
     return fig
 
 
-@pytest.mark.mpl_image_compare(remove_text=True,
-                               tolerance=0.6 if mpl_version_before('3.5') else 0.)
+@pytest.mark.mpl_image_compare(
+    remove_text=True, tolerance=0.6 if version_check('matplotlib==3.5') else 0.)
 def test_hodograph_units():
     """Test passing quantities to Hodograph."""
     fig = plt.figure(figsize=(9, 9))

tests/plots/test_util.py

@@ -11,7 +11,7 @@
 import xarray as xr
 
 from metpy.plots import add_metpy_logo, add_timestamp, add_unidata_logo, convert_gempak_color
-from metpy.testing import get_test_data, mpl_version_before
+from metpy.testing import get_test_data, version_check
 
 
 @pytest.mark.mpl_image_compare(tolerance=2.638, remove_text=True)
@@ -91,8 +91,9 @@ def test_add_logo_invalid_size():
         add_metpy_logo(fig, size='jumbo')
 
 
-@pytest.mark.mpl_image_compare(tolerance=1.072 if mpl_version_before('3.5') else 0,
-                               remove_text=True)
+@pytest.mark.mpl_image_compare(
+    tolerance=1.072 if version_check('matplotlib<3.5') else 0,
+    remove_text=True)
 def test_gempak_color_image_compare():
     """Test creating a plot with all the GEMPAK colors."""
     c = range(32)
@@ -111,8 +112,9 @@ def test_gempak_color_image_compare():
     return fig
 
 
-@pytest.mark.mpl_image_compare(tolerance=1.215 if mpl_version_before('3.5') else 0,
-                               remove_text=True)
+@pytest.mark.mpl_image_compare(
+    tolerance=1.215 if version_check('matplotlib<3.5') else 0,
+    remove_text=True)
 def test_gempak_color_xw_image_compare():
     """Test creating a plot with all the GEMPAK colors using xw style."""
     c = range(32)

tests/test_testing.py

@@ -10,7 +10,7 @@
 
 from metpy.deprecation import MetpyDeprecationWarning
 from metpy.testing import (assert_array_almost_equal, check_and_drop_units,
-                           check_and_silence_deprecation)
+                           check_and_silence_deprecation, version_check)
 
 
 # Test #1183: numpy.testing.assert_array* ignores any masked value, so work-around
@@ -42,3 +42,27 @@ def test_check_and_drop_units_with_dataarray():
     assert isinstance(actual, np.ndarray)
     assert isinstance(desired, np.ndarray)
     np.testing.assert_array_almost_equal(actual, desired)
+
+
+def test_module_version_check():
+    """Test parsing and version comparison of installed package."""
+    numpy_version = np.__version__
+    assert version_check(f'numpy >={numpy_version}')
+
+
+def test_module_version_check_outdated_spec():
+    """Test checking test version specs against package metadata."""
+    with pytest.raises(ValueError, match='Specified numpy'):
+        version_check('numpy>0.0.0')
+
+
+def test_module_version_check_nonsense():
+    """Test failed pattern match of package specification."""
+    with pytest.raises(ValueError, match='Invalid version '):
+        version_check('thousands of birds picking packages')
+
+
+def test_module_version_check_invalid_comparison():
+    """Test invalid operator in version comparison."""
+    with pytest.raises(ValueError, match='Comparison operator << '):
+        version_check('numpy << 36')