Adds tests

A simple test that checks the consistency of sampling a colorscale
on the actual definition points, as well as sampling a very simple
scale at simple points.

Author: CarlAndersson

packages/python/plotly/plotly/tests/test_core/test_colors/test_colors.py

@@ -137,3 +137,22 @@ def test_make_colorscale(self):
         self.assertRaisesRegexp(
             PlotlyError, pattern2, colors.make_colorscale, color_list2, scale
         )
+
+    def test_sample_colorscale(self):
+
+        # test that sampling a colorscale at the defined points returns the same
+        defined_colors = colors.sequential.Inferno
+        sampled_colors = colors.sample_colorscale(defined_colors, len(defined_colors), colortype="rgb")
+        defined_colors_rgb = colors.convert_colors_to_same_type(defined_colors, colortype='rgb')[0]
+        self.assertEqual(sampled_colors, defined_colors_rgb)
+
+        # test sampling an easy colorscale that goes [red, green, blue]
+        defined_colors = ['rgb(255,0,0)', 'rgb(0,255,0)', 'rgb(0,0,255)']
+        samplepoints = [0.0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1.0]
+        expected_output = [
+            (1.0, 0.0, 0.0), (0.75, 0.25, 0.0), (0.5, 0.5, 0.0),
+            (0.25, 0.75, 0.0), (0.0, 1.0, 0.0), (0.0, 0.75, 0.25),
+            (0.0, 0.5, 0.5), (0.0, 0.25, 0.75), (0.0, 0.0, 1.0)
+        ]
+        output = colors.sample_colorscale(defined_colors, samplepoints, colortype="tuple")
+        self.assertEqual(expected_output, output)