add more eps file tests

Tests/test_file_eps.py

@@ -28,34 +28,47 @@
 # EPS test files with binary preview
 FILE3 = "Tests/images/binary_preview_map.eps"
 
+# Three unsigned 32bit little-endian values:
+#   0xC6D3D0C5 magic number
+#   byte position of start of postscript section (12)
+#   byte length of postscript section (0)
+# this byte length isn't valid, but we don't read it
+simple_binary_header = b"\xc5\xd0\xd3\xc6\x0c\x00\x00\x00\x00\x00\x00\x00"
+
+# taken from page 8 of the specification
+# https://web.archive.org/web/20220120164601/https://www.adobe.com/content/dam/acom/en/devnet/actionscript/articles/5002.EPSF_Spec.pdf
+simple_eps_file = (
+    b"%!PS-Adobe-3.0 EPSF-3.0",
+    b"%%BoundingBox: 5 5 105 105",
+    b"10 setlinewidth",
+    b"10 10 moveto",
+    b"0 90 rlineto 90 0 rlineto 0 -90 rlineto closepath",
+    b"stroke",
+)
+simple_eps_file_with_comments = (
+    simple_eps_file[:1]
+    + (
+        b"%%Comment1: Some Value",
+        b"%%SecondComment: Another Value",
+    )
+    + simple_eps_file[1:]
+)
+simple_eps_file_without_version = simple_eps_file[1:]
+simple_eps_file_without_boundingbox = simple_eps_file[:1] + simple_eps_file[2:]
 
-@pytest.mark.skipif(not HAS_GHOSTSCRIPT, reason="Ghostscript not available")
-def test_sanity():
-    # Regular scale
-    with Image.open(FILE1) as image1:
-        image1.load()
-        assert image1.mode == "RGB"
-        assert image1.size == (460, 352)
-        assert image1.format == "EPS"
-
-    with Image.open(FILE2) as image2:
-        image2.load()
-        assert image2.mode == "RGB"
-        assert image2.size == (360, 252)
-        assert image2.format == "EPS"
-
-    # Double scale
-    with Image.open(FILE1) as image1_scale2:
-        image1_scale2.load(scale=2)
-        assert image1_scale2.mode == "RGB"
-        assert image1_scale2.size == (920, 704)
-        assert image1_scale2.format == "EPS"
 
-    with Image.open(FILE2) as image2_scale2:
-        image2_scale2.load(scale=2)
-        assert image2_scale2.mode == "RGB"
-        assert image2_scale2.size == (720, 504)
-        assert image2_scale2.format == "EPS"
+@pytest.mark.skipif(not HAS_GHOSTSCRIPT, reason="Ghostscript not available")
+@pytest.mark.parametrize(
+    ("filename", "size"), ((FILE1, (460, 352)), (FILE2, (360, 252)))
+)
+@pytest.mark.parametrize("scale", (None, 1, 2))
+def test_sanity(filename, size, scale):
+    expected_size = tuple((s if scale is None else s * scale) for s in size)
+    with Image.open(filename) as image:
+        image.load(scale=scale)
+        assert image.mode == "RGB"
+        assert image.size == expected_size
+        assert image.format == "EPS"
 
 
 @pytest.mark.skipif(not HAS_GHOSTSCRIPT, reason="Ghostscript not available")
@@ -69,18 +82,36 @@ def test_load():
 
 def test_invalid_file():
     invalid_file = "Tests/images/flower.jpg"
-
     with pytest.raises(SyntaxError):
         EpsImagePlugin.EpsImageFile(invalid_file)
 
 
+def test_binary_header_only():
+    data = io.BytesIO(simple_binary_header)
+    with pytest.raises(SyntaxError, match='EPS header missing "%!PS-Adobe" comment'):
+        EpsImagePlugin.EpsImageFile(data)
+
+
+@pytest.mark.parametrize("prefix", (b"", simple_binary_header))
+def test_missing_version_comment(prefix):
+    data = io.BytesIO(prefix + b"\n".join(simple_eps_file_without_version))
+    with pytest.raises(SyntaxError):
+        EpsImagePlugin.EpsImageFile(data)
+
+
+@pytest.mark.parametrize("prefix", (b"", simple_binary_header))
+def test_missing_boundingbox_comment(prefix):
+    data = io.BytesIO(prefix + b"\n".join(simple_eps_file_without_boundingbox))
+    with pytest.raises(SyntaxError, match='EPS header missing "%%BoundingBox" comment'):
+        EpsImagePlugin.EpsImageFile(data)
+
+
 @mark_if_feature_version(
     pytest.mark.valgrind_known_error, "libjpeg_turbo", "2.0", reason="Known Failing"
 )
 @pytest.mark.skipif(not HAS_GHOSTSCRIPT, reason="Ghostscript not available")
 def test_cmyk():
     with Image.open("Tests/images/pil_sample_cmyk.eps") as cmyk_image:
-
         assert cmyk_image.mode == "CMYK"
         assert cmyk_image.size == (100, 100)
         assert cmyk_image.format == "EPS"
@@ -101,7 +132,7 @@ def test_showpage():
         with Image.open("Tests/images/reqd_showpage.png") as target:
             # should not crash/hang
             plot_image.load()
-            #  fonts could be slightly different
+            # fonts could be slightly different
             assert_image_similar(plot_image, target, 6)
 
 
@@ -112,7 +143,7 @@ def test_transparency():
         assert plot_image.mode == "RGBA"
 
         with Image.open("Tests/images/reqd_showpage_transparency.png") as target:
-            #  fonts could be slightly different
+            # fonts could be slightly different
             assert_image_similar(plot_image, target, 6)
 
 
@@ -207,7 +238,6 @@ def test_resize(filename):
 @pytest.mark.parametrize("filename", (FILE1, FILE2))
 def test_thumbnail(filename):
     # Issue #619
-    # Arrange
     with Image.open(filename) as im:
         new_size = (100, 100)
         im.thumbnail(new_size)
@@ -256,24 +286,13 @@ def _test_readline_file_psfile(test_string, ending):
         _test_readline_file_psfile(s, ending)
 
 
+@pytest.mark.parametrize("prefix", (b"", simple_binary_header))
 @pytest.mark.parametrize(
     "line_ending",
     (b"\r\n", b"\n", b"\n\r", b"\r"),
 )
-def test_readline(line_ending):
-    simple_file = line_ending.join(
-        (
-            b"%!PS-Adobe-3.0 EPSF-3.0",
-            b"%%Comment1: Some Value",
-            b"%%SecondComment: Another Value",
-            b"%%BoundingBox: 5 5 105 105",
-            b"10 setlinewidth",
-            b"10 10 moveto",
-            b"0 90 rlineto 90 0 rlineto 0 -90 rlineto closepath",
-            b"stroke",
-        )
-    )
-
+def test_readline(prefix, line_ending):
+    simple_file = prefix + line_ending.join(simple_eps_file_with_comments)
     data = io.BytesIO(simple_file)
     test_file = EpsImagePlugin.EpsImageFile(data)
     assert test_file.info["Comment1"] == "Some Value"