narsil 0.3.1

A terminal-based system resource monitor — GPU-aware, Braille charts, per-char label inversion
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185

// Copyright (C) 2026 Raimo Geisel
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

//! Tests for [`crate::ui::widgets::SplitGauge`].
//!
//! [`SplitGauge`] is rendered directly into a [`Buffer`] (no terminal
//! required). Tests verify:
//!
//! * `ratio` clamping above 1.0 and below 0.0,
//! * that filled cells use `bar_color` as background and [`Color::Black`] as
//!   foreground,
//! * that unfilled cells use `bar_color` as foreground and the default
//!   background,
//! * the correct fill/unfill boundary at ratio = 0.5,
//! * that the label is rendered centred across the bar,
//! * that using a block confines the gauge to the block's inner area,
//! * and that a zero-size area does not cause a panic.

use ratatui::{
    buffer::Buffer,
    layout::{Position, Rect},
    style::Color,
    widgets::{Block, Borders, Widget},
};

use crate::ui::widgets::SplitGauge;

// ── ratio clamping ────────────────────────────────────────────────────────────

/// A ratio greater than 1.0 is clamped to 1.0: every cell must be filled.
#[test]
fn test_ratio_clamped_above_one() {
    let area = Rect::new(0, 0, 6, 1);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(2.0, Color::Green, "").render(area, &mut buf);
    for x in 0..6u16 {
        let cell = buf.cell(Position { x, y: 0 }).unwrap();
        assert_eq!(cell.bg, Color::Green, "x={x} should be filled (bg=Green)");
    }
}

/// A ratio less than 0.0 is clamped to 0.0: no cell must be filled.
#[test]
fn test_ratio_clamped_below_zero() {
    let area = Rect::new(0, 0, 6, 1);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(-1.0, Color::Red, "").render(area, &mut buf);
    for x in 0..6u16 {
        let cell = buf.cell(Position { x, y: 0 }).unwrap();
        assert_ne!(cell.bg, Color::Red, "x={x} should not be filled (bg≠Red)");
    }
}

// ── fill coverage ─────────────────────────────────────────────────────────────

/// With ratio 1.0, every cell in the bar area has `bg = bar_color` and
/// `fg = Color::Black`.
#[test]
fn test_full_fill_all_cells_inverted() {
    let area = Rect::new(0, 0, 10, 1);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(1.0, Color::Cyan, "").render(area, &mut buf);
    for x in 0..10u16 {
        let cell = buf.cell(Position { x, y: 0 }).unwrap();
        assert_eq!(cell.bg, Color::Cyan, "x={x}: expected filled bg");
        assert_eq!(cell.fg, Color::Black, "x={x}: expected filled fg");
    }
}

/// With ratio 0.0, no cell has `bg = bar_color`; all cells have `fg = bar_color`.
#[test]
fn test_empty_fill_no_cells_inverted() {
    let area = Rect::new(0, 0, 10, 1);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(0.0, Color::Yellow, "").render(area, &mut buf);
    for x in 0..10u16 {
        let cell = buf.cell(Position { x, y: 0 }).unwrap();
        assert_ne!(cell.bg, Color::Yellow, "x={x} should not be filled");
        assert_eq!(cell.fg, Color::Yellow, "x={x} should use bar_color as fg");
    }
}

/// With ratio 0.5 and width 10, the first 5 cells (0–4) are filled and the
/// last 5 cells (5–9) are unfilled.
#[test]
fn test_half_fill_correct_boundary() {
    let area = Rect::new(0, 0, 10, 1);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(0.5, Color::Magenta, "").render(area, &mut buf);

    for x in 0..5u16 {
        let cell = buf.cell(Position { x, y: 0 }).unwrap();
        assert_eq!(cell.bg, Color::Magenta, "x={x} should be filled");
    }
    for x in 5..10u16 {
        let cell = buf.cell(Position { x, y: 0 }).unwrap();
        assert_ne!(cell.bg, Color::Magenta, "x={x} should be unfilled");
    }
}

// ── label rendering ───────────────────────────────────────────────────────────

/// The label is centred across the bar width. For a 10-wide gauge and a
/// 3-character label `"42%"`, the label starts at column 3 ( = (10−3)/2 ).
#[test]
fn test_label_is_centred() {
    let label = "42%";
    let area = Rect::new(0, 0, 10, 1);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(0.0, Color::Green, label).render(area, &mut buf);

    // label_start = (10 - 3) / 2 = 3
    let expected_chars = ['4', '2', '%'];
    for (i, &ch) in expected_chars.iter().enumerate() {
        let x = 3 + i as u16;
        let cell = buf.cell(Position { x, y: 0 }).unwrap();
        assert_eq!(
            cell.symbol(),
            ch.to_string(),
            "column {x} should contain '{ch}'"
        );
    }
}

// ── block integration ─────────────────────────────────────────────────────────

/// When a block with `Borders::ALL` is attached, the gauge fills its inner
/// area. Border cells must not be coloured with `bar_color`.
#[test]
fn test_with_block_gauge_stays_inside_border() {
    // outer 12×3, inner 10×1 at (1, 1)
    let area = Rect::new(0, 0, 12, 3);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(1.0, Color::Blue, "")
        .block(Block::default().borders(Borders::ALL))
        .render(area, &mut buf);

    // Inner cells at y=1, x=1..=10 must all be filled.
    for x in 1..=10u16 {
        let cell = buf.cell(Position { x, y: 1 }).unwrap();
        assert_eq!(cell.bg, Color::Blue, "inner cell ({x},1) should be filled");
    }

    // Top and bottom border rows must NOT be filled.
    for x in 0..12u16 {
        for y in [0u16, 2u16] {
            let cell = buf.cell(Position { x, y }).unwrap();
            assert_ne!(
                cell.bg,
                Color::Blue,
                "border cell ({x},{y}) must not be filled"
            );
        }
    }
}

// ── edge cases ────────────────────────────────────────────────────────────────

/// Rendering into a zero-width area must not panic (early return guard).
#[test]
fn test_zero_width_does_not_panic() {
    let area = Rect::new(0, 0, 0, 1);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(0.5, Color::Green, "50%").render(area, &mut buf);
}

/// Rendering into a zero-height area must not panic (early return guard).
#[test]
fn test_zero_height_does_not_panic() {
    let area = Rect::new(0, 0, 10, 0);
    let mut buf = Buffer::empty(area);
    SplitGauge::new(0.5, Color::Green, "50%").render(area, &mut buf);
}