color tests to 100% (#2078)

* color tests to 100%

* tweak

* remove overly complex code

src/textual/color.py

@@ -297,7 +297,7 @@ class Color(NamedTuple):
             A CSS hex-style color, e.g. "#46b3de"
 
         """
-        r, g, b, a = self.clamped
+        r, g, b, _a = self.clamped
         return f"#{r:02X}{g:02X}{b:02X}"
 
     @property
@@ -504,7 +504,9 @@ class Color(NamedTuple):
             a = clamp(float(a), 0.0, 1.0)
             color = Color.from_hsl(h, s, l).with_alpha(a)
         else:
-            raise AssertionError("Can't get here if RE_COLOR matches")
+            raise AssertionError(  # pragma: no-cover
+                "Can't get here if RE_COLOR matches"
+            )
         return color
 
     @lru_cache(maxsize=1024)
@@ -545,10 +547,7 @@ class Color(NamedTuple):
         Returns:
             A new color, either an off-white or off-black
         """
-        brightness = self.brightness
-        white_contrast = abs(brightness - WHITE.brightness)
-        black_contrast = abs(brightness - BLACK.brightness)
-        return (WHITE if white_contrast > black_contrast else BLACK).with_alpha(alpha)
+        return (WHITE if self.brightness < 0.5 else BLACK).with_alpha(alpha)
 
 
 class Gradient:
@@ -566,12 +565,12 @@ class Gradient:
         Raises:
             ValueError: If any stops are missing (must be at least a stop for 0 and 1).
         """
-        self.stops = sorted(stops)
+        self._stops = sorted(stops)
         if len(stops) < 2:
             raise ValueError("At least 2 stops required.")
-        if self.stops[0][0] != 0.0:
+        if self._stops[0][0] != 0.0:
             raise ValueError("First stop must be 0.")
-        if self.stops[-1][0] != 1.0:
+        if self._stops[-1][0] != 1.0:
             raise ValueError("Last stop must be 1.")
 
     def get_color(self, position: float) -> Color:
@@ -588,13 +587,13 @@ class Gradient:
         """
         # TODO: consider caching
         position = clamp(position, 0.0, 1.0)
-        for (stop1, color1), (stop2, color2) in zip(self.stops, self.stops[1:]):
+        for (stop1, color1), (stop2, color2) in zip(self._stops, self._stops[1:]):
             if stop2 >= position >= stop1:
                 return color1.blend(
                     color2,
                     (position - stop1) / (stop2 - stop1),
                 )
-        return self.stops[-1][1]
+        raise AssertionError("Can't get here if `_stops` is valid")
 
 
 # Color constants

tests/test_color.py

@@ -42,7 +42,7 @@ def test_rgb():
     assert Color(10, 20, 30, 0.55).rgb == (10, 20, 30)
 
 
-def test_hls():
+def test_hsl():
     red = Color(200, 20, 32)
     print(red.hsl)
     assert red.hsl == pytest.approx(
@@ -51,6 +51,7 @@ def test_hls():
     assert Color.from_hsl(
         0.9888888888888889, 0.818181818181818, 0.43137254901960786
     ).normalized == pytest.approx(red.normalized, rel=1e-5)
+    assert red.hsl.css == "hsl(356,81.8%,43.1%)"
 
 
 def test_color_brightness():
@@ -65,6 +66,12 @@ def test_color_hex():
     assert Color(255, 0, 127, 0.5).hex == "#FF007F7F"
 
 
+def test_color_hex6():
+    assert Color(0, 0, 0).hex6 == "#000000"
+    assert Color(255, 255, 255, 0.25).hex6 == "#FFFFFF"
+    assert Color(255, 0, 127, 0.5).hex6 == "#FF007F"
+
+
 def test_color_css():
     assert Color(255, 0, 127).css == "rgb(255,0,127)"
     assert Color(255, 0, 127, 0.5).css == "rgba(255,0,127,0.5)"
@@ -74,6 +81,11 @@ def test_color_with_alpha():
     assert Color(255, 50, 100).with_alpha(0.25) == Color(255, 50, 100, 0.25)
 
 
+def test_multiply_alpha():
+    assert Color(100, 100, 100).multiply_alpha(0.5) == Color(100, 100, 100, 0.5)
+    assert Color(100, 100, 100, 0.5).multiply_alpha(0.5) == Color(100, 100, 100, 0.25)
+
+
 def test_color_blend():
     assert Color(0, 0, 0).blend(Color(255, 255, 255), 0) == Color(0, 0, 0)
     assert Color(0, 0, 0).blend(Color(255, 255, 255), 1.0) == Color(255, 255, 255)
@@ -149,6 +161,7 @@ def test_color_parse_color():
 
 def test_color_add():
     assert Color(50, 100, 200) + Color(10, 20, 30, 0.9) == Color(14, 28, 47)
+    assert Color(50, 100, 200).__add__("foo") == NotImplemented
 
 
 # Computed with http://www.easyrgb.com/en/convert.php,
@@ -220,6 +233,10 @@ def test_inverse():
 def test_gradient_errors():
     with pytest.raises(ValueError):
         Gradient()
+    with pytest.raises(ValueError):
+        Gradient((0.1, Color.parse("red")))
+    with pytest.raises(ValueError):
+        Gradient((0.1, Color.parse("red")), (1, Color.parse("blue")))
     with pytest.raises(ValueError):
         Gradient((0, Color.parse("red")))
 
@@ -243,3 +260,7 @@ def test_gradient():
     assert gradient.get_color(1.2) == Color(0, 255, 0)
     assert gradient.get_color(0.5) == Color(0, 0, 255)
     assert gradient.get_color(0.7) == Color(0, 101, 153)
+
+    gradient._stops.pop()
+    with pytest.raises(AssertionError):
+        gradient.get_color(1.0)