Fix color-lightening and darkening calculations

* lisp/color.el (color-lighten-hsl): Fix calculations (bug#74055).

* test/lisp/color-tests.el (color-tests-lighten-hsl)
(color-tests-lighten-name, color-tests-darken-hsl)
(color-tests-darken-name): Adjust test results.

1 files changed, 7 insertions, 10 deletions

diff --git a/test/lisp/color-tests.el b/test/lisp/color-tests.el
index bc897edc702..63cb024bb8d 100644
--- a/test/lisp/color-tests.el
+++ b/test/lisp/color-tests.el
@@ -220,32 +220,29 @@
 
 (ert-deftest color-tests-lighten-hsl ()
   (should (equal (color-lighten-hsl 360 0.5 0.5 0) '(360 0.5 0.5)))
-  (should (equal (color-lighten-hsl 360 0.5 0.5 -10) '(360 0.5 0.4)))
+  (should (equal (color-lighten-hsl 360 0.5 0.5 -10) '(360 0.5 0.45)))
   (should (equal (color-lighten-hsl 360 0.5 0.5 -500) '(360 0.5 0.0)))
-  (should
-   (color-tests--approx-equal
-    (color-lighten-hsl 120 0.5 0.8 5) '(120 0.5 0.85)))
-  (should
-   (equal (color-lighten-hsl 120 0.5 0.8 500) '(120 0.5 1.0))))
+  (should (equal (color-lighten-hsl 120 0.5 0.8 5) '(120 0.5 0.81)))
+  (should (equal (color-lighten-hsl 120 0.5 0.8 500) '(120 0.5 1.0))))
 
 (ert-deftest color-tests-lighten-name ()
   (should (equal (color-lighten-name "black" 100) "#ffffffffffff"))
   (should (equal (color-lighten-name "white" 100) "#ffffffffffff"))
   (should (equal (color-lighten-name "red" 0) "#ffff00000000"))
-  (should (equal (color-lighten-name "red" 10) "#ffff33323332")))
+  (should (equal (color-lighten-name "red" 10) "#ffff19991999")))
 
 (ert-deftest color-tests-darken-hsl ()
   (should (equal (color-darken-hsl 360 0.5 0.5 0) '(360 0.5 0.5)))
-  (should (equal (color-darken-hsl 360 0.5 0.5 -10) '(360 0.5 0.6)))
+  (should (equal (color-darken-hsl 360 0.5 0.5 -10) '(360 0.5 0.55)))
   (should (equal (color-darken-hsl 360 0.5 0.5 -500) '(360 0.5 1.0)))
-  (should (equal (color-darken-hsl 120 0.5 0.8 5) '(120 0.5 0.75)))
+  (should (equal (color-darken-hsl 120 0.5 0.8 5) '(120 0.5 0.76)))
   (should (equal (color-darken-hsl 120 0.5 0.8 500) '(120 0.5 0.0))))
 
 (ert-deftest color-tests-darken-name ()
   (should (equal (color-darken-name "black" 100) "#000000000000"))
   (should (equal (color-darken-name "white" 100) "#000000000000"))
   (should (equal (color-darken-name "red" 0) "#ffff00000000"))
-  (should (equal (color-darken-name "red" 10) "#cccc00000000")))
+  (should (equal (color-darken-name "red" 10) "#e66500000000")))
 
 (ert-deftest color-tests-oklab-to-xyz ()
   (should (color-tests--approx-equal (color-oklab-to-xyz 0 0 0) '(0.0 0.0 0.0)))