make tests more lenient

Author: Conengmo

tests/test_utilities.py

@@ -187,4 +187,13 @@ def test_write_png_rgb():
 )
 def test_linear_gradient(hex_list: List[str], n_colors: int, expected_output: List[str]):
     result = ut.linear_gradient(hex_list, n_colors)
-    assert result == expected_output
+    assert len(result) == len(expected_output), "Output length mismatch"
+
+    # because we rewrote this function, we allow a difference of 1 between the old and the new version
+    tolerance = 1
+    for actual, expected in zip(result, expected_output):
+        r1, g1, b1 = (int(actual[i:i+2], 16) for i in (1, 3, 5))
+        r2, g2, b2 = (int(expected[i:i+2], 16) for i in (1, 3, 5))
+        if not all(abs(a - b) <= tolerance for a, b in zip((r1, g1, b1), (r2, g2, b2))):
+            # to get a nice output, assert the full array when we spot a failure
+            assert result == expected_output