From 2ca9e01bc86d302def859626303f09d321e90596 Mon Sep 17 00:00:00 2001
From: facelessuser <faceless.shop@gmail.com>
Date: Tue, 10 May 2022 14:27:23 -0600
Subject: [PATCH] Fix cat16 not applying the matrix

---
 coloraide/cat.py                     |  2 +-
 docs/src/markdown/about/changelog.md |  1 +
 tests/test_cat.py                    | 33 ++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_cat.py

diff --git a/coloraide/cat.py b/coloraide/cat.py
index 882b88788..15cb06c7f 100644
--- a/coloraide/cat.py
+++ b/coloraide/cat.py
@@ -232,7 +232,7 @@ class CAT16(VonKries):
 
     NAME = "cat16"
 
-    M = [
+    MATRIX = [
         [-0.401288, -0.250268, -0.002079],
         [0.650173, 1.204414, 0.048952],
         [-0.051461, -0.045854, -0.953127]
diff --git a/docs/src/markdown/about/changelog.md b/docs/src/markdown/about/changelog.md
index 07663e9f9..8623c5f3c 100644
--- a/docs/src/markdown/about/changelog.md
+++ b/docs/src/markdown/about/changelog.md
@@ -5,6 +5,7 @@
 - **NEW**: Allow dictionary input to use aliases in the dictionary.
 - **FIX**: If too many channels are given to a color space via raw data, ensure the operation fails.
 - **FIX**: Sync up achromatic logic of the Okhsl and Okhsv `normalize` function with the actual conversion algorithm.
+- **FIX**: Regression that caused `cat16` not to work due to a misnamed variable.
 
 ## 0.17.0
 
diff --git a/tests/test_cat.py b/tests/test_cat.py
new file mode 100644
index 000000000..929dc7337
--- /dev/null
+++ b/tests/test_cat.py
@@ -0,0 +1,33 @@
+"""Test chromatic adaptation."""
+from coloraide import Color
+from coloraide import cat
+from coloraide import util as cutil
+from . import util
+import pytest
+
+
+class TestCAT(util.ColorAssertsPyTest):
+    """Test CAT."""
+
+    @pytest.mark.parametrize(
+        'method,cat1,cat2',
+        [
+            ('bradford', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50']),
+            ('von-kries', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50']),
+            ('xyz-scaling', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50']),
+            ('cat02', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50']),
+            ('cmccat97', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50']),
+            ('sharp', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50']),
+            ('cmccat2000', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50']),
+            ('cat16', cat.WHITES['2deg']['D65'], cat.WHITES['2deg']['D50'])
+
+        ]
+    )
+    def test_cat(self, method, cat1, cat2):
+        """Test CAT methods."""
+
+        c1 = Color('white').convert('xyz-d65')
+        c2 = Color('xyz-d50', c1.chromatic_adaptation(cat1, cat2, c1[:-1], method=method))
+        c3 = Color('xyz-d65', c2.chromatic_adaptation(cat2, cat1, c2[:-1], method=method))
+        self.assertColorEqual(c1, c3)
+        self.assertColorEqual(c2, Color('xyz-d50', cutil.xy_to_xyz(cat2)))