Fix `TextCanvas` `CanvasError("Attribute extends beyond text...")` (#555)HEADmaster

* Fix TextCanvas `CanvasError("Attribute extends beyond text...")

* `[[]] * ...` causes
  list of 1 list with pointers
  amount equal to multiplier
  instead of "list of lists"
* Add 2 basic font tests which check for Canvas create issue
* Add few type annotations during debug process

Fix: #554

* Force tests to restore default encoding in tearDown

Tests order change should not cause tests failures

---------

Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/urwid/tests/test_font.py b/urwid/tests/test_font.py
new file mode 100644
index 0000000..3c9be7a
--- /dev/null
+++ b/urwid/tests/test_font.py
@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+import unittest
+
+import urwid
+
+
+class TestFontRender(unittest.TestCase):
+    def setUp(self) -> None:
+        self.old_encoding = urwid.util._target_encoding
+        urwid.set_encoding("utf-8")
+
+    def tearDown(self) -> None:
+        urwid.set_encoding(self.old_encoding)
+
+    def test_001_basic(self):
+        font = urwid.Thin3x3Font()
+        rendered = b'\n'.join(font.render("1").text).decode()
+        expected = ' ┐ \n │ \n ┴ '
+        self.assertEqual(expected, rendered)
+
+    def test_002_non_rect(self):
+        """Test non rect symbol, which causes spaces based padding.
+
+        Lines as bytes should be not equal length.
+        """
+        font = urwid.Thin3x3Font()
+        rendered = b'\n'.join(font.render("2").text).decode()
+        expected = '┌─┐\n┌─┘\n└─ '
+        self.assertEqual(expected, rendered)