TestLogitLocator: append a test on nonsingular to avoid issues as #14743

jb-leger · jb-leger · commit 787f6b8bb164 · 2019-07-31T11:29:25.000+02:00
diff --git a/lib/matplotlib/tests/test_ticker.py b/lib/matplotlib/tests/test_ticker.py
@@ -1,5 +1,6 @@
 import warnings
 import re
+import itertools
 
 import numpy as np
 from numpy.testing import assert_almost_equal, assert_array_equal
@@ -366,6 +367,44 @@ def test_minor_attr(self):
         loc.set_params(minor=False)
         assert not loc.minor
 
+    acceptable_vmin_vmax = [
+        *(2.5 ** np.arange(-3, 0)),
+        *(1 - 2.5 ** np.arange(-3, 0)),
+    ]
+
+    @pytest.mark.parametrize(
+        "lims",
+        [
+            (a, b)
+            for (a, b) in itertools.product(acceptable_vmin_vmax, repeat=2)
+            if a != b
+        ],
+    )
+    def test_nonsingular_ok(self, lims):
+        """
+        Create logit locator, and test the nonsingular method for acceptable
+        value
+        """
+        loc = mticker.LogitLocator()
+        lims2 = loc.nonsingular(*lims)
+        assert lims == lims2
+
+    @pytest.mark.parametrize("okval", acceptable_vmin_vmax)
+    def test_nonsingular_nok(self, okval):
+        """
+        Create logit locator, and test the nonsingular method for non
+        acceptable value
+        """
+        loc = mticker.LogitLocator()
+        vmin, vmax = (-1, okval)
+        vmin2, vmax2 = loc.nonsingular(vmin, vmax)
+        assert vmax2 == vmax
+        assert 0 < vmin2 < vmax2
+        vmin, vmax = (okval, 2)
+        vmin2, vmax2 = loc.nonsingular(vmin, vmax)
+        assert vmin2 == vmin
+        assert vmin2 < vmax2 < 1
+
 
 class TestFixedLocator:
     def test_set_params(self):
