Refactor test cases for improved readability and consistency

- Added blank lines for better separation of test cases in multiple test files.
- Reformatted event handling in tests for clarity and consistency.
- Ensured consistent use of multi-line formatting for dictionary arguments in event handling.
- Improved assertions and test descriptions for better understanding.
- Updated test cases across various modules including test_stream_state, test_stream_utils, test_summarization, test_thread_selector, test_tool_error_handler, test_tui_widgets, test_ui_runtime, and test_wechat_channel.

tests/test_diff_format.py

@@ -17,6 +17,7 @@ from EvoScientist.stream.diff_format import (
 # _escape_markup
 # ---------------------------------------------------------------------------
 
+
 class TestEscapeMarkup:
     def test_escapes_brackets(self):
         assert _escape_markup("[bold]text[/bold]") == r"\[bold\]text\[/bold\]"
@@ -35,6 +36,7 @@ class TestEscapeMarkup:
 # _detect_unicode_support
 # ---------------------------------------------------------------------------
 
+
 class TestDetectUnicodeSupport:
     def test_utf8_encoding(self):
         with mock.patch("sys.stdout") as mock_stdout:
@@ -60,6 +62,7 @@ class TestDetectUnicodeSupport:
 # format_diff_rich
 # ---------------------------------------------------------------------------
 
+
 class TestFormatDiffRich:
     def test_empty_diff_returns_dim_message(self):
         result = format_diff_rich("")
@@ -143,6 +146,7 @@ class TestFormatDiffRich:
 # build_edit_diff
 # ---------------------------------------------------------------------------
 
+
 class TestBuildEditDiff:
     def test_returns_none_when_equal(self):
         assert build_edit_diff("/foo.py", "same", "same") is None
@@ -195,6 +199,7 @@ class TestBuildEditDiff:
 # Integration with format_tool_result_compact
 # ---------------------------------------------------------------------------
 
+
 class TestFormatToolResultCompactEditFile:
     def test_edit_file_with_tool_args_shows_diff(self):
         from EvoScientist.stream.display import format_tool_result_compact