ai-agent/internal/tui/scroll_test.go

package tui

import (
    "strings"
    "testing"

    "charm.land/lipgloss/v2"
)

// TestNoHorizontalScroll verifies that rendered content never exceeds viewport width
func TestNoHorizontalScroll(t *testing.T) {
    tests := []struct {
        name         string
        screenWidth  int
        panelVisible bool
        content      string
    }{
        {
            name:         "long word with panel",
            screenWidth:  120,
            panelVisible: true,
            content:      strings.Repeat("x", 150),
        },
        {
            name:         "multiple long words without panel",
            screenWidth:  100,
            panelVisible: false,
            content:      strings.Repeat("superlongword ", 10),
        },
        {
            name:         "code block with panel",
            screenWidth:  120,
            panelVisible: true,
            content:      "```\n" + strings.Repeat("x", 100) + "\n```",
        },
        {
            name:         "URL without panel",
            screenWidth:  80,
            panelVisible: false,
            content:      "https://example.com/" + strings.Repeat("verylongpathsegment/", 5),
        },
    }

    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            // Calculate panel width
            panelWidth := 0
            if tt.panelVisible {
                panelWidth = 30
                if tt.screenWidth < 100 {
                    panelWidth = 25
                } else if tt.screenWidth > 160 {
                    panelWidth = 40
                }
            }

            // Calculate viewport width (from model.go)
            viewportWidth := tt.screenWidth - 1
            if tt.panelVisible {
                viewportWidth = tt.screenWidth - panelWidth - 2
            }
            if viewportWidth < 20 {
                viewportWidth = 20
            }

            // Calculate content width (from view.go)
            contentW := tt.screenWidth - 4
            if tt.panelVisible {
                contentW = tt.screenWidth - panelWidth - 5
            }
            if contentW < 20 {
                contentW = 20
            }

            // Wrap the content
            wrapped := wrapText(tt.content, contentW)

            // Check each line
            lines := strings.Split(wrapped, "\n")
            for i, line := range lines {
                // Measure visible width (lipgloss.Width handles styling)
                lineWidth := lipgloss.Width(line)
                if lineWidth > viewportWidth {
                    t.Errorf("line %d width %d exceeds viewport width %d: %q",
                        i, lineWidth, viewportWidth, line[:min(50, len(line))])
                }
                if lineWidth > contentW {
                    t.Errorf("line %d width %d exceeds content width %d",
                        i, lineWidth, contentW)
                }
            }
        })
    }
}

// TestResponsivePanelToggle verifies no scroll when toggling panel
func TestResponsivePanelToggle(t *testing.T) {
    screenWidth := 120
    content := strings.Repeat("longword ", 20)

    // Calculate widths with panel
    panelWidth := 30
    viewportWithPanel := screenWidth - panelWidth - 2
    contentWithPanel := screenWidth - panelWidth - 5

    // Calculate widths without panel
    viewportWithoutPanel := screenWidth - 1
    contentWithoutPanel := screenWidth - 4

    // Wrap content for both scenarios
    wrappedWithPanel := wrapText(content, contentWithPanel)
    wrappedWithoutPanel := wrapText(content, contentWithoutPanel)

    // Verify both fit within their respective viewports
    for i, line := range strings.Split(wrappedWithPanel, "\n") {
        if lipgloss.Width(line) > viewportWithPanel {
            t.Errorf("with panel: line %d exceeds viewport", i)
        }
    }

    for i, line := range strings.Split(wrappedWithoutPanel, "\n") {
        if lipgloss.Width(line) > viewportWithoutPanel {
            t.Errorf("without panel: line %d exceeds viewport", i)
        }
    }

    // Verify that content without panel is wider (better use of space)
    if contentWithoutPanel <= contentWithPanel {
        t.Error("content width should increase when panel is hidden")
    }
}

// TestEdgeCases verifies width handling at boundary conditions
func TestEdgeCases(t *testing.T) {
    tests := []struct {
        name        string
        screenWidth int
        expectMin   bool // whether minimum width constraint should kick in
    }{
        {"minimum viable", 46, true},  // 25 (panel) + 1 + 20 (min viewport)
        {"just above min", 50, false},
        {"exactly 100", 100, false},
        {"exactly 160", 160, false},
        {"very large", 300, false},
    }

    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            panelWidth := 30
            if tt.screenWidth < 100 {
                panelWidth = 25
            } else if tt.screenWidth > 160 {
                panelWidth = 40
            }

            viewportWidth := tt.screenWidth - panelWidth - 2
            if viewportWidth < 20 {
                viewportWidth = 20
            }

            if tt.expectMin && viewportWidth == 20 {
                // Expected minimum enforcement
                if tt.screenWidth-panelWidth-2 >= 20 {
                    t.Error("expected minimum width enforcement but calculation would allow larger")
                }
            }

            // Verify viewport never exceeds available space (unless minimum enforced)
            maxAllowed := tt.screenWidth - panelWidth - 1
            if viewportWidth > maxAllowed && !tt.expectMin {
                t.Errorf("viewport %d exceeds max allowed %d", viewportWidth, maxAllowed)
            }
        })
    }
}

func min(a, b int) int {
    if a < b {
        return a
    }
    return b
}