Only use colors from the palette file

Tests/test_file_gimppalette.py

@@ -29,17 +29,8 @@ def test_get_palette():
     palette, mode = palette_file.getpalette()
 
     # Assert
-    assert mode == "RGB"
-
-
-def test_palette__has_correct_color_indexes():
-    # Arrange
-    with open("Tests/images/custom_gimp_palette.gpl", "rb") as fp:
-        palette_file = GimpPaletteFile(fp)
-
-    palette, mode = palette_file.getpalette()
-
-    colors_in_test_palette = [
+    expected_palette = b""
+    for color in (
         (0, 0, 0),
         (65, 38, 30),
         (103, 62, 49),
@@ -48,15 +39,7 @@ def test_palette__has_correct_color_indexes():
         (208, 127, 100),
         (151, 144, 142),
         (221, 207, 199),
-    ]
-
-    for i, color in enumerate(colors_in_test_palette):
-        assert tuple(palette[i * 3 : i * 3 + 3]) == color
-
-
-def test_palette_counts_number_of_colors_in_file():
-    # Arrange
-    with open("Tests/images/custom_gimp_palette.gpl", "rb") as fp:
-        palette_file = GimpPaletteFile(fp)
-
-    assert palette_file.n_colors == 8
+    ):
+        expected_palette += bytes(color)
+    assert palette == expected_palette
+    assert mode == "RGB"

src/PIL/GimpPaletteFile.py

@@ -26,28 +26,27 @@ class GimpPaletteFile:
 
     def __init__(self, fp):
 
-        palette = bytearray(b"".join([o8(i) * 3 for i in range(256)]))
-
         if fp.readline()[:12] != b"GIMP Palette":
             raise SyntaxError("not a GIMP palette file")
 
-        index = 0
-        for s in fp:
+        self.palette = b""
+        while len(self.palette) < 768:
+
+            s = fp.readline()
+            if not s:
+                break
+
             # skip fields and comment lines
             if re.match(rb"\w+:|#", s):
                 continue
             if len(s) > 100:
                 raise SyntaxError("bad palette file")
 
-            v = tuple(map(int, s.split()[:3]))
+            v = s.split()
             if len(v) < 3:
                 raise ValueError("bad palette entry")
-
-            palette[index * 3 : index * 3 + 3] = v
-            index += 1
-
-        self.palette = bytes(palette)
-        self.n_colors = index
+            for i in range(3):
+                self.palette += o8(int(v[i]))
 
     def getpalette(self):