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Testing Windows Console Terminal Operations in Textualize/rich

This test suite validates the Windows console functionality in the Rich library, focusing on cursor manipulation, text styling, and console buffer operations. The tests ensure proper handling of Windows-specific terminal operations and style attributes.
Test Coverage Overview

The test suite provides comprehensive coverage of Windows console operations including:
Cursor positioning and movement
Text styling and attributes
Screen buffer manipulation
Console window properties
Edge cases include boundary conditions for cursor movement, style combinations, and buffer operations.
Implementation Analysis

The testing approach uses pytest fixtures and mock objects to simulate Windows console behavior. Key patterns include:
Mock patching of Win32 API calls
Fixture-based test setup
Coordinate system validation
Style attribute verification
Technical Details

Testing tools and configuration:
pytest framework with fixtures
unittest.mock for Win32 API simulation
Windows-specific coordinate system (COORD)
Style parsing and attribute mapping
Console buffer info structures
Best Practices Demonstrated

The test suite exemplifies quality testing practices through:
Isolated test cases with clear assertions
Comprehensive mock objects
Platform-specific test skipping
Structured fixture organization
Thorough edge case coverage
textualize/rich

tests/test_win32_console.py
            
import dataclasses
import sys
from unittest import mock
from unittest.mock import patch

import pytest

from rich.style import Style

if sys.platform == "win32":
    from rich import _win32_console
    from rich._win32_console import COORD, LegacyWindowsTerm, WindowsCoordinates

    CURSOR_X = 1
    CURSOR_Y = 2
    CURSOR_POSITION = WindowsCoordinates(row=CURSOR_Y, col=CURSOR_X)
    SCREEN_WIDTH = 20
    SCREEN_HEIGHT = 30
    DEFAULT_STYLE_ATTRIBUTE = 16
    CURSOR_SIZE = 25

    @dataclasses.dataclass
    class StubScreenBufferInfo:
        dwCursorPosition: COORD = COORD(CURSOR_X, CURSOR_Y)
        dwSize: COORD = COORD(SCREEN_WIDTH, SCREEN_HEIGHT)
        wAttributes: int = DEFAULT_STYLE_ATTRIBUTE

    pytestmark = pytest.mark.skipif(sys.platform != "win32", reason="windows only")

    def test_windows_coordinates_to_ctype():
        coord = WindowsCoordinates.from_param(WindowsCoordinates(row=1, col=2))
        assert coord.X == 2
        assert coord.Y == 1

    @pytest.fixture
    def win32_handle():
        handle = mock.sentinel
        with mock.patch.object(_win32_console, "GetStdHandle", return_value=handle):
            yield handle

    @pytest.fixture
    def win32_console_getters():
        def stub_console_cursor_info(std_handle, cursor_info):
            cursor_info.dwSize = CURSOR_SIZE
            cursor_info.bVisible = True

        with mock.patch.object(
            _win32_console,
            "GetConsoleScreenBufferInfo",
            return_value=StubScreenBufferInfo,
        ) as GetConsoleScreenBufferInfo, mock.patch.object(
            _win32_console, "GetConsoleCursorInfo", side_effect=stub_console_cursor_info
        ) as GetConsoleCursorInfo:
            yield {
                "GetConsoleScreenBufferInfo": GetConsoleScreenBufferInfo,
                "GetConsoleCursorInfo": GetConsoleCursorInfo,
            }

    def test_cursor_position(win32_console_getters):
        term = LegacyWindowsTerm(sys.stdout)
        assert term.cursor_position == WindowsCoordinates(row=CURSOR_Y, col=CURSOR_X)

    def test_screen_size(win32_console_getters):
        term = LegacyWindowsTerm(sys.stdout)
        assert term.screen_size == WindowsCoordinates(
            row=SCREEN_HEIGHT, col=SCREEN_WIDTH
        )

    def test_write_text(win32_console_getters, win32_handle, capsys):
        text = "Hello, world!"
        term = LegacyWindowsTerm(sys.stdout)

        term.write_text(text)

        captured = capsys.readouterr()
        assert captured.out == text

    @patch.object(_win32_console, "SetConsoleTextAttribute")
    def test_write_styled(
        SetConsoleTextAttribute,
        win32_console_getters,
        win32_handle,
        capsys,
    ):
        style = Style.parse("black on red")
        text = "Hello, world!"
        term = LegacyWindowsTerm(sys.stdout)

        term.write_styled(text, style)

        captured = capsys.readouterr()
        assert captured.out == text

        # Ensure we set the text attributes and then reset them after writing styled text
        call_args = SetConsoleTextAttribute.call_args_list
        assert len(call_args) == 2
        first_args, first_kwargs = call_args[0]
        second_args, second_kwargs = call_args[1]

        assert first_args == (win32_handle,)
        assert first_kwargs["attributes"].value == 64
        assert second_args == (win32_handle,)
        assert second_kwargs["attributes"] == DEFAULT_STYLE_ATTRIBUTE

    @patch.object(_win32_console, "SetConsoleTextAttribute")
    def test_write_styled_bold(
        SetConsoleTextAttribute, win32_console_getters, win32_handle
    ):
        style = Style.parse("bold black on red")
        text = "Hello, world!"
        term = LegacyWindowsTerm(sys.stdout)

        term.write_styled(text, style)

        call_args = SetConsoleTextAttribute.call_args_list
        first_args, first_kwargs = call_args[0]

        expected_attr = 64 + 8  # 64 for red bg, +8 for bright black
        assert first_args == (win32_handle,)
        assert first_kwargs["attributes"].value == expected_attr

    @patch.object(_win32_console, "SetConsoleTextAttribute")
    def test_write_styled_reverse(
        SetConsoleTextAttribute, win32_console_getters, win32_handle
    ):
        style = Style.parse("reverse red on blue")
        text = "Hello, world!"
        term = LegacyWindowsTerm(sys.stdout)

        term.write_styled(text, style)

        call_args = SetConsoleTextAttribute.call_args_list
        first_args, first_kwargs = call_args[0]

        expected_attr = 64 + 1  # 64 for red bg (after reverse), +1 for blue fg
        assert first_args == (win32_handle,)
        assert first_kwargs["attributes"].value == expected_attr

    @patch.object(_win32_console, "SetConsoleTextAttribute")
    def test_write_styled_reverse(
        SetConsoleTextAttribute, win32_console_getters, win32_handle
    ):
        style = Style.parse("dim bright_red on blue")
        text = "Hello, world!"
        term = LegacyWindowsTerm(sys.stdout)

        term.write_styled(text, style)

        call_args = SetConsoleTextAttribute.call_args_list
        first_args, first_kwargs = call_args[0]

        expected_attr = 4 + 16  # 4 for red text (after dim), +16 for blue bg
        assert first_args == (win32_handle,)
        assert first_kwargs["attributes"].value == expected_attr

    @patch.object(_win32_console, "SetConsoleTextAttribute")
    def test_write_styled_no_foreground_color(
        SetConsoleTextAttribute, win32_console_getters, win32_handle
    ):
        style = Style.parse("on blue")
        text = "Hello, world!"
        term = LegacyWindowsTerm(sys.stdout)

        term.write_styled(text, style)

        call_args = SetConsoleTextAttribute.call_args_list
        first_args, first_kwargs = call_args[0]

        expected_attr = 16 | term._default_fore  # 16 for blue bg, plus default fg color
        assert first_args == (win32_handle,)
        assert first_kwargs["attributes"].value == expected_attr

    @patch.object(_win32_console, "SetConsoleTextAttribute")
    def test_write_styled_no_background_color(
        SetConsoleTextAttribute, win32_console_getters, win32_handle
    ):
        style = Style.parse("blue")
        text = "Hello, world!"
        term = LegacyWindowsTerm(sys.stdout)

        term.write_styled(text, style)

        call_args = SetConsoleTextAttribute.call_args_list
        first_args, first_kwargs = call_args[0]

        expected_attr = (
            16 | term._default_back
        )  # 16 for blue foreground, plus default bg color
        assert first_args == (win32_handle,)
        assert first_kwargs["attributes"].value == expected_attr

    @patch.object(_win32_console, "FillConsoleOutputCharacter", return_value=None)
    @patch.object(_win32_console, "FillConsoleOutputAttribute", return_value=None)
    def test_erase_line(
        FillConsoleOutputAttribute,
        FillConsoleOutputCharacter,
        win32_console_getters,
        win32_handle,
    ):
        term = LegacyWindowsTerm(sys.stdout)
        term.erase_line()
        start = WindowsCoordinates(row=CURSOR_Y, col=0)
        FillConsoleOutputCharacter.assert_called_once_with(
            win32_handle, " ", length=SCREEN_WIDTH, start=start
        )
        FillConsoleOutputAttribute.assert_called_once_with(
            win32_handle, DEFAULT_STYLE_ATTRIBUTE, length=SCREEN_WIDTH, start=start
        )

    @patch.object(_win32_console, "FillConsoleOutputCharacter", return_value=None)
    @patch.object(_win32_console, "FillConsoleOutputAttribute", return_value=None)
    def test_erase_end_of_line(
        FillConsoleOutputAttribute,
        FillConsoleOutputCharacter,
        win32_console_getters,
        win32_handle,
    ):
        term = LegacyWindowsTerm(sys.stdout)
        term.erase_end_of_line()

        FillConsoleOutputCharacter.assert_called_once_with(
            win32_handle, " ", length=SCREEN_WIDTH - CURSOR_X, start=CURSOR_POSITION
        )
        FillConsoleOutputAttribute.assert_called_once_with(
            win32_handle,
            DEFAULT_STYLE_ATTRIBUTE,
            length=SCREEN_WIDTH - CURSOR_X,
            start=CURSOR_POSITION,
        )

    @patch.object(_win32_console, "FillConsoleOutputCharacter", return_value=None)
    @patch.object(_win32_console, "FillConsoleOutputAttribute", return_value=None)
    def test_erase_start_of_line(
        FillConsoleOutputAttribute,
        FillConsoleOutputCharacter,
        win32_console_getters,
        win32_handle,
    ):
        term = LegacyWindowsTerm(sys.stdout)
        term.erase_start_of_line()

        start = WindowsCoordinates(CURSOR_Y, 0)

        FillConsoleOutputCharacter.assert_called_once_with(
            win32_handle, " ", length=CURSOR_X, start=start
        )
        FillConsoleOutputAttribute.assert_called_once_with(
            win32_handle, DEFAULT_STYLE_ATTRIBUTE, length=CURSOR_X, start=start
        )

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_to(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        coords = WindowsCoordinates(row=4, col=5)
        term = LegacyWindowsTerm(sys.stdout)

        term.move_cursor_to(coords)

        SetConsoleCursorPosition.assert_called_once_with(win32_handle, coords=coords)

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_to_out_of_bounds_row(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        coords = WindowsCoordinates(row=-1, col=4)
        term = LegacyWindowsTerm(sys.stdout)

        term.move_cursor_to(coords)

        assert not SetConsoleCursorPosition.called

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_to_out_of_bounds_col(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        coords = WindowsCoordinates(row=10, col=-4)
        term = LegacyWindowsTerm(sys.stdout)

        term.move_cursor_to(coords)

        assert not SetConsoleCursorPosition.called

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_up(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        term = LegacyWindowsTerm(sys.stdout)

        term.move_cursor_up()

        SetConsoleCursorPosition.assert_called_once_with(
            win32_handle, coords=WindowsCoordinates(row=CURSOR_Y - 1, col=CURSOR_X)
        )

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_down(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        term = LegacyWindowsTerm(sys.stdout)

        term.move_cursor_down()

        SetConsoleCursorPosition.assert_called_once_with(
            win32_handle, coords=WindowsCoordinates(row=CURSOR_Y + 1, col=CURSOR_X)
        )

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_forward(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        term = LegacyWindowsTerm(sys.stdout)

        term.move_cursor_forward()

        SetConsoleCursorPosition.assert_called_once_with(
            win32_handle, coords=WindowsCoordinates(row=CURSOR_Y, col=CURSOR_X + 1)
        )

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_forward_newline_wrap(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        cursor_at_end_of_line = StubScreenBufferInfo(
            dwCursorPosition=COORD(SCREEN_WIDTH - 1, CURSOR_Y)
        )
        win32_console_getters[
            "GetConsoleScreenBufferInfo"
        ].return_value = cursor_at_end_of_line
        term = LegacyWindowsTerm(sys.stdout)
        term.move_cursor_forward()

        SetConsoleCursorPosition.assert_called_once_with(
            win32_handle, coords=WindowsCoordinates(row=CURSOR_Y + 1, col=0)
        )

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_to_column(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        term = LegacyWindowsTerm(sys.stdout)
        term.move_cursor_to_column(5)
        SetConsoleCursorPosition.assert_called_once_with(
            win32_handle, coords=WindowsCoordinates(CURSOR_Y, 5)
        )

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_backward(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        term = LegacyWindowsTerm(sys.stdout)
        term.move_cursor_backward()
        SetConsoleCursorPosition.assert_called_once_with(
            win32_handle, coords=WindowsCoordinates(row=CURSOR_Y, col=CURSOR_X - 1)
        )

    @patch.object(_win32_console, "SetConsoleCursorPosition", return_value=None)
    def test_move_cursor_backward_prev_line_wrap(
        SetConsoleCursorPosition, win32_console_getters, win32_handle
    ):
        cursor_at_start_of_line = StubScreenBufferInfo(
            dwCursorPosition=COORD(0, CURSOR_Y)
        )
        win32_console_getters[
            "GetConsoleScreenBufferInfo"
        ].return_value = cursor_at_start_of_line
        term = LegacyWindowsTerm(sys.stdout)
        term.move_cursor_backward()
        SetConsoleCursorPosition.assert_called_once_with(
            win32_handle,
            coords=WindowsCoordinates(row=CURSOR_Y - 1, col=SCREEN_WIDTH - 1),
        )

    @patch.object(_win32_console, "SetConsoleCursorInfo", return_value=None)
    def test_hide_cursor(SetConsoleCursorInfo, win32_console_getters, win32_handle):
        term = LegacyWindowsTerm(sys.stdout)
        term.hide_cursor()

        call_args = SetConsoleCursorInfo.call_args_list

        assert len(call_args) == 1

        args, kwargs = call_args[0]
        assert kwargs["cursor_info"].bVisible == 0
        assert kwargs["cursor_info"].dwSize == CURSOR_SIZE

    @patch.object(_win32_console, "SetConsoleCursorInfo", return_value=None)
    def test_show_cursor(SetConsoleCursorInfo, win32_console_getters, win32_handle):
        term = LegacyWindowsTerm(sys.stdout)
        term.show_cursor()

        call_args = SetConsoleCursorInfo.call_args_list

        assert len(call_args) == 1

        args, kwargs = call_args[0]
        assert kwargs["cursor_info"].bVisible == 1
        assert kwargs["cursor_info"].dwSize == CURSOR_SIZE

    @patch.object(_win32_console, "SetConsoleTitle", return_value=None)
    def test_set_title(SetConsoleTitle, win32_console_getters):
        term = LegacyWindowsTerm(sys.stdout)
        term.set_title("title")

        SetConsoleTitle.assert_called_once_with("title")

    @patch.object(_win32_console, "SetConsoleTitle", return_value=None)
    def test_set_title_too_long(_, win32_console_getters):
        term = LegacyWindowsTerm(sys.stdout)

        with pytest.raises(AssertionError):
            term.set_title("a" * 255)