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Validating Console Text Alignment Features in Textualize/rich

This test suite validates the alignment functionality in Rich’s console text rendering system, focusing on horizontal and vertical text positioning capabilities. It ensures proper text alignment behavior across different console widths and styling options.

Test Coverage Overview

The test suite provides comprehensive coverage of Rich’s alignment features:

Horizontal alignment (left, center, right)
Vertical alignment (top, middle, bottom)
Combined alignment scenarios
Edge cases with varying text lengths and console widths
Style preservation during alignment

Implementation Analysis

The testing approach utilizes pytest’s fixture system and assertion mechanisms to verify alignment behavior. Tests employ Console mock objects with StringIO to capture and verify output formatting, ensuring precise character positioning and style application.

Technical Details

Testing tools and configuration:

pytest framework for test organization
StringIO for output capture
Console class with configurable width/height
Measurement class for dimension validation
Rich’s Align and VerticalCenter components

Best Practices Demonstrated

The test suite exemplifies testing best practices through:

Isolated test cases for each alignment type
Explicit validation of error conditions
Comprehensive edge case coverage
Clear test naming conventions
Consistent assertion patterns

textualize/rich

tests/test_align.py

            
import io

import pytest

from rich.console import Console
from rich.align import Align, VerticalCenter
from rich.measure import Measurement


def test_bad_align_legal():
    # Legal
    Align("foo", "left")
    Align("foo", "center")
    Align("foo", "right")

    # illegal
    with pytest.raises(ValueError):
        Align("foo", None)
    with pytest.raises(ValueError):
        Align("foo", "middle")
    with pytest.raises(ValueError):
        Align("foo", "")
    with pytest.raises(ValueError):
        Align("foo", "LEFT")
    with pytest.raises(ValueError):
        Align("foo", vertical="somewhere")


def test_repr():
    repr(Align("foo", "left"))
    repr(Align("foo", "center"))
    repr(Align("foo", "right"))


def test_align_left():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo", "left"))
    assert console.file.getvalue() == "foo       
"


def test_align_center():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo", "center"))
    assert console.file.getvalue() == "   foo    
"


def test_align_right():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo", "right"))
    assert console.file.getvalue() == "       foo
"


def test_align_top():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo", vertical="top"), height=5)
    expected = "foo       
          
          
          
          
"
    result = console.file.getvalue()
    print(repr(result))
    assert result == expected


def test_align_middle():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo", vertical="middle"), height=5)
    expected = "          
          
foo       
          
          
"
    result = console.file.getvalue()
    print(repr(result))
    assert result == expected


def test_align_bottom():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo", vertical="bottom"), height=5)
    expected = "          
          
          
          
foo       
"
    result = console.file.getvalue()
    print(repr(result))
    assert result == expected


def test_align_center_middle():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo
bar", "center", vertical="middle"), height=5)
    expected = "          
   foo    
   bar    
          
          
"
    result = console.file.getvalue()
    print(repr(result))
    assert result == expected


def test_align_fit():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foobarbaze", "center"))
    assert console.file.getvalue() == "foobarbaze
"


def test_align_right_style():
    console = Console(
        file=io.StringIO(),
        width=10,
        color_system="truecolor",
        force_terminal=True,
        _environ={},
    )
    console.print(Align("foo", "right", style="on blue"))
    assert console.file.getvalue() == "\x1b[44m       \x1b[0m\x1b[44mfoo\x1b[0m
"


def test_measure():
    console = Console(file=io.StringIO(), width=20)
    _min, _max = Measurement.get(console, console.options, Align("foo bar", "left"))
    assert _min == 3
    assert _max == 7


def test_align_no_pad():
    console = Console(file=io.StringIO(), width=10)
    console.print(Align("foo", "center", pad=False))
    console.print(Align("foo", "left", pad=False))
    assert console.file.getvalue() == "   foo
foo
"


def test_align_width():
    console = Console(file=io.StringIO(), width=40)
    words = "Deep in the human unconscious is a pervasive need for a logical universe that makes sense. But the real universe is always one step beyond logic"
    console.print(Align(words, "center", width=30))
    result = console.file.getvalue()
    expected = "     Deep in the human unconscious      
     is a pervasive need for a          
     logical universe that makes        
     sense. But the real universe       
     is always one step beyond          
     logic                              
"
    assert result == expected


def test_shortcuts():
    assert Align.left("foo").align == "left"
    assert Align.left("foo").renderable == "foo"
    assert Align.right("foo").align == "right"
    assert Align.right("foo").renderable == "foo"
    assert Align.center("foo").align == "center"
    assert Align.center("foo").renderable == "foo"


def test_vertical_center():
    console = Console(color_system=None, height=6)
    console.begin_capture()
    vertical_center = VerticalCenter("foo")
    repr(vertical_center)
    console.print(vertical_center)
    result = console.end_capture()
    print(repr(result))
    expected = "   
   
foo
   
   
   
"
    assert result == expected
    assert Measurement.get(console, console.options, vertical_center) == Measurement(
        3, 3
    )