Add type annotations to unit tests.

Added types to all tests, except (for now):
- test_completion.py
- test_print_formatted_text.py

Also, the types are not yet --strict.

tests/test_async_generator.py

@@ -1,12 +1,14 @@
+from typing import Iterator
+
 from prompt_toolkit.eventloop import generator_to_async_generator, get_event_loop
 
 
-def _sync_generator():
+def _sync_generator() -> Iterator[int]:
  yield 1
  yield 10
 
 
-def test_generator_to_async_generator():
+def test_generator_to_async_generator() -> None:
  """
  Test conversion of sync to asycn generator.
  This should run the synchronous parts in a background thread.
@@ -15,7 +17,7 @@ def test_generator_to_async_generator():
 
  items = []
 
- async def consume_async_generator():
+ async def consume_async_generator() -> None:
  async for item in async_gen:
  items.append(item)
 

tests/test_buffer.py

@@ -4,23 +4,23 @@
 
 
 @pytest.fixture
-def _buffer():
+def _buffer() -> Buffer:
  buff = Buffer()
  return buff
 
 
-def test_initial(_buffer):
+def test_initial(_buffer: Buffer) -> None:
  assert _buffer.text == ""
  assert _buffer.cursor_position == 0
 
 
-def test_insert_text(_buffer):
+def test_insert_text(_buffer: Buffer) -> None:
  _buffer.insert_text("some_text")
  assert _buffer.text == "some_text"
  assert _buffer.cursor_position == len("some_text")
 
 
-def test_cursor_movement(_buffer):
+def test_cursor_movement(_buffer: Buffer) -> None:
  _buffer.insert_text("some_text")
  _buffer.cursor_left()
  _buffer.cursor_left()
@@ -32,7 +32,7 @@ def test_cursor_movement(_buffer):
  assert _buffer.cursor_position == len("some_teA")
 
 
-def test_backspace(_buffer):
+def test_backspace(_buffer: Buffer) -> None:
  _buffer.insert_text("some_text")
  _buffer.cursor_left()
  _buffer.cursor_left()
@@ -42,7 +42,7 @@ def test_backspace(_buffer):
  assert _buffer.cursor_position == len("some_t")
 
 
-def test_cursor_up(_buffer):
+def test_cursor_up(_buffer: Buffer) -> None:
  # Cursor up to a line thats longer.
  _buffer.insert_text("long line1\nline2")
  _buffer.cursor_up()
@@ -61,7 +61,7 @@ def test_cursor_up(_buffer):
  assert _buffer.document.cursor_position == 5
 
 
-def test_cursor_down(_buffer):
+def test_cursor_down(_buffer: Buffer) -> None:
  _buffer.insert_text("line1\nline2")
  _buffer.cursor_position = 3
 
@@ -78,7 +78,7 @@ def test_cursor_down(_buffer):
  assert _buffer.document.cursor_position == len("long line1\na")
 
 
-def test_join_next_line(_buffer):
+def test_join_next_line(_buffer: Buffer) -> None:
  _buffer.insert_text("line1\nline2\nline3")
  _buffer.cursor_up()
  _buffer.join_next_line()
@@ -94,14 +94,14 @@ def test_join_next_line(_buffer):
  assert _buffer.text == "line1"
 
 
-def test_newline(_buffer):
+def test_newline(_buffer: Buffer) -> None:
  _buffer.insert_text("hello world")
  _buffer.newline()
 
  assert _buffer.text == "hello world\n"
 
 
-def test_swap_characters_before_cursor(_buffer):
+def test_swap_characters_before_cursor(_buffer: Buffer) -> None:
  _buffer.insert_text("hello world")
  _buffer.cursor_left()
  _buffer.cursor_left()