add test for {1bpp, 2bpp, 4bpp, 8bpp} bitmap fonts

Author: nulano

Tests/fonts/DejaVuSans-24-1.ttf

@@ -12,6 +12,9 @@ BungeeColor-Regular_colr_Windows.ttf, from https://github.com/djrrb/bungee
 All of the above fonts are published under the SIL Open Font License (OFL) v1.1 (http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=OFL), which allows you to copy, modify, and redistribute them if you need to.
 
 
+DejaVuSans-24-{1,2,4,8}.ttf are based on DejaVuSans.ttf converted using FontForge.
+
+
 10x20-ISO8859-1.pcf, from https://packages.ubuntu.com/xenial/xfonts-base
 
 "Public domain font.  Share and enjoy."

Tests/fonts/DejaVuSans-24-2.ttf

@@ -2,7 +2,7 @@
 
 from PIL import Image, ImageDraw, ImageFont
 
-from .helper import assert_image_similar
+from .helper import assert_image_equal_tofile, assert_image_similar, skip_unless_feature
 
 image_font_installed = True
 try:
@@ -41,3 +41,21 @@ def test_similar():
         font=font_outline,
     )
     assert_image_similar(im_bitmap, im_outline, 4)
+
+
+@skip_unless_feature("freetype2")
+@pytest.mark.parametrize("bpp", (1, 2, 4, 8))
+def test_bitmap_font(bpp):
+    text = "Bitmap Font"
+    target = f"Tests/images/bitmap_font_{bpp}.png"
+    font = ImageFont.truetype(
+        f"Tests/fonts/DejaVuSans-24-{bpp}.ttf",
+        24,
+        layout_engine=ImageFont.LAYOUT_BASIC,
+    )
+
+    im = Image.new("RGB", (160, 35), "white")
+    draw = ImageDraw.Draw(im)
+    draw.text((2, 2), text, "black", font)
+
+    assert_image_equal_tofile(im, target)