tests: add test_contourf_with_conflict_points

lib/cartopy/tests/mpl/test_contour.py

@@ -146,3 +146,22 @@ def test_contourf_transform_first(func):
     test_func(xx, yy, z, transform=ccrs.PlateCarree(),
               transform_first=False)
     assert_array_almost_equal(ax.get_extent(), (-180, 180, -25, 25))
+
+def test_contourf_with_conflict_points():
+    """Testing the issue mentioned in #2370"""
+    lons = [96.75, 97.  , 97.25]
+    lats = np.arange(17.25, 15.9, -0.25)
+
+    lons, lats = np.meshgrid(lons, lats)
+
+    data = [[26.9, 43.7, 26.8],
+            [33.2, 65.8, 34.6],
+            [54.7, 66.9, 55.5],
+            [65.3, 65. , 65.7],
+            [65.9, 65. , 65.6],
+            [65.8, 65.2, 65.5]]
+
+    fig = plt.figure()
+    ax = fig.add_subplot(projection=ccrs.Mercator())
+    ax.contourf(lons, lats, data, levels=[60, 65], transform=ccrs.PlateCarree())
+    plt.draw()