BadNote/test/viewport_fit_test.dart

// Tests for viewport fit/centering math (F3).

import 'dart:ui' show Offset, Size;

import 'package:flutter_test/flutter_test.dart';

import 'package:badnote/editor/layout/viewport_fit.dart';

void main() {
  test('fitWidthScale fills the viewport width', () {
    expect(fitWidthScale(const Size(500, 800), 1000), 2.0);
    expect(fitWidthScale(const Size(0, 800), 1000), 0);
  });

  test('fitPageScale is the limiting (min) axis, letterboxed', () {
    // content 500x1000 into 1000x1000: w-fit=2, h-fit=1 → min 1.
    expect(fitPageScale(const Size(500, 1000), const Size(1000, 1000)), 1.0);
    // content 1000x500 into 1000x1000: w-fit=1, h-fit=2 → min 1.
    expect(fitPageScale(const Size(1000, 500), const Size(1000, 1000)), 1.0);
    expect(fitPageScale(const Size(0, 0), const Size(100, 100)), 0);
  });

  test('centerOffset centers smaller content', () {
    // content 200x100 at scale 1 in 1000x600 → offset (400, 250).
    expect(
      centerOffset(const Size(200, 100), const Size(1000, 600), 1.0),
      const Offset(400, 250),
    );
  });

  test('centerOffset is negative when scaled content overflows', () {
    // content 1000x1000 at scale 2 = 2000 in a 1000 viewport → (-500, -500).
    expect(
      centerOffset(const Size(1000, 1000), const Size(1000, 1000), 2.0),
      const Offset(-500, -500),
    );
  });

  test('fit-to-width then center yields a left-anchored x for a tall page', () {
    const content = Size(500, 2000);
    const viewport = Size(1000, 800);
    final scale = fitWidthScale(content, viewport.width); // 2.0
    final off = centerOffset(content, viewport, scale);
    // Scaled width = 1000 == viewport width → x offset 0.
    expect(off.dx, 0);
    // Scaled height 4000 > 800 → negative y (overflows, scrollable).
    expect(off.dy, lessThan(0));
  });
}