From 8859d8669d03c9d67eee3a5adc06feece91b4868 Mon Sep 17 00:00:00 2001
From: Cosimo Lupo <clupo@google.com>
Date: Tue, 21 Mar 2023 17:24:20 +0000
Subject: [PATCH] ttFont_test: add tests for unseekable input file with
 lazy=True

---
 Tests/ttLib/ttFont_test.py | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/Tests/ttLib/ttFont_test.py b/Tests/ttLib/ttFont_test.py
index f726ad45c..2203b4d9c 100644
--- a/Tests/ttLib/ttFont_test.py
+++ b/Tests/ttLib/ttFont_test.py
@@ -286,3 +286,35 @@ def test_spooled_tempfile_may_not_have_attribute_seekable():
     font.save(tmp)
     # this should not fail
     _ = TTFont(tmp)
+
+
+def test_unseekable_file_lazy_loading_fails():
+    class NonSeekableFile:
+        def __init__(self):
+            self.file = io.BytesIO()
+
+        def read(self, size):
+            return self.file.read(size)
+
+        def seekable(self):
+            return False
+
+    f = NonSeekableFile()
+    with pytest.raises(TTLibError, match="Input file must be seekable when lazy=True"):
+        TTFont(f, lazy=True)
+
+
+def test_unsupported_seek_operation_lazy_loading_fails():
+    class UnsupportedSeekFile:
+        def __init__(self):
+            self.file = io.BytesIO()
+
+        def read(self, size):
+            return self.file.read(size)
+
+        def seek(self, offset):
+            raise io.UnsupportedOperation("Unsupported seek operation")
+
+    f = UnsupportedSeekFile()
+    with pytest.raises(TTLibError, match="Input file must be seekable when lazy=True"):
+        TTFont(f, lazy=True)