Add tests for IndexFormatter

dstansby · dstansby · commit dfa3b357c30a · 2019-12-17T17:15:43.000Z
diff --git a/lib/matplotlib/tests/test_ticker.py b/lib/matplotlib/tests/test_ticker.py
@@ -447,6 +447,20 @@ def test_set_params(self):
         assert sym.numticks == 8
 
 
+class TestIndexFormatter:
+    @pytest.mark.parametrize('x, label', [(-2, ''),
+                                          (-1, 'label0'),
+                                          (0, 'label0'),
+                                          (0.5, 'label1'),
+                                          (1, 'label1'),
+                                          (1.5, 'label2'),
+                                          (2, 'label2'),
+                                          (2.5, '')])
+    def test_formatting(self, x, label):
+        formatter = mticker.IndexFormatter(['label0', 'label1', 'label2'])
+        assert formatter(x) == label
+
+
 class TestScalarFormatter:
     offset_data = [
         (123, 189, 0),
