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Merged
andrew-bierman merged 6 commits into from
May 7, 2026
Merged

feat(units): weight math audit — new @packrat/units package with NIST constants and 174 tests #2388

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59fb5b2
feat(units): add @packrat/units package and migrate all weight math
andrew-bierman May 7, 2026
779c3a7
fix(checks): add prefers-reduced-motion CSS and bump expo patch versions
andrew-bierman May 7, 2026
2b2e3b3
fix(units): replace raw typeof with isString from @packrat/guards
andrew-bierman May 7, 2026
354b814
Merge branch 'main' into feat/weight-audit
andrew-bierman May 7, 2026
3289309
fix(units): avoid noUncheckedIndexedAccess TS errors in percentage test
andrew-bierman May 7, 2026
cfbb19f
fix(units): align WEIGHT_UNITS order with @packrat/api/types ('g','oz…
andrew-bierman May 7, 2026
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21 changes: 7 additions & 14 deletions apps/expo/features/pack-templates/utils/computePacktemplateWeight.ts
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Original file line number Diff line number Diff line change
@@ -1,33 +1,26 @@
import { convertFromGrams, convertToGrams } from 'expo-app/features/packs/utils';
import type { PackTemplate, WeightUnit } from '../types';
import type { WeightUnit } from '@packrat/units';
import { displayWeight, normalize, parseWeightUnit } from '@packrat/units';
import type { PackTemplate } from '../types';

export const computePackTemplateWeights = (
template: Omit<PackTemplate, 'baseWeight' | 'totalWeight'>,
preferredUnit: WeightUnit = 'g',
): PackTemplate => {
// Initialize weights
let baseWeightGrams = 0;
let totalWeightGrams = 0;

// Calculate weights based on items
for (const item of template.items) {
const itemWeightInGrams = convertToGrams(item.weight, item.weightUnit) * item.quantity;

const itemWeightInGrams =
normalize(item.weight, parseWeightUnit(item.weightUnit)) * item.quantity;
totalWeightGrams += itemWeightInGrams;

if (!item.consumable && !item.worn) {
baseWeightGrams += itemWeightInGrams;
}
}

// Convert back to preferred unit
const baseWeight = convertFromGrams(baseWeightGrams, preferredUnit);
const totalWeight = convertFromGrams(totalWeightGrams, preferredUnit);

// Return updated template with computed weights
return {
...template,
baseWeight: Number(baseWeight.toFixed(2)),
totalWeight: Number(totalWeight.toFixed(2)),
baseWeight: displayWeight(baseWeightGrams, preferredUnit),
totalWeight: displayWeight(totalWeightGrams, preferredUnit),
};
};
93 changes: 22 additions & 71 deletions apps/expo/features/packs/utils/__tests__/convertFromGrams.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,6 @@ import { describe, expect, it } from 'vitest';
import { convertFromGrams } from '../convertFromGrams';

describe('convertFromGrams', () => {
// -------------------------------------------------------------------------
// Metric conversions
// -------------------------------------------------------------------------
describe('metric conversions', () => {
it('returns same value for grams', () => {
expect(convertFromGrams(100, 'g')).toBe(100);
Expand All @@ -20,26 +17,20 @@ describe('convertFromGrams', () => {
});
});

// -------------------------------------------------------------------------
// Imperial conversions
// -------------------------------------------------------------------------
describe('imperial conversions', () => {
describe('imperial conversions (NIST avoirdupois values)', () => {
it('converts grams to ounces correctly', () => {
expect(convertFromGrams(28.35, 'oz')).toBeCloseTo(1, 2);
expect(convertFromGrams(56.7, 'oz')).toBeCloseTo(2, 1);
expect(convertFromGrams(14.175, 'oz')).toBeCloseTo(0.5, 2);
expect(convertFromGrams(28.349523125, 'oz')).toBe(1); // exact NIST value
expect(convertFromGrams(56.69904625, 'oz')).toBeCloseTo(2, 10);
expect(convertFromGrams(14.174761562, 'oz')).toBeCloseTo(0.5, 8);
});

it('converts grams to pounds correctly', () => {
expect(convertFromGrams(453.59, 'lb')).toBeCloseTo(1, 2);
expect(convertFromGrams(907.18, 'lb')).toBeCloseTo(2, 2);
expect(convertFromGrams(226.795, 'lb')).toBeCloseTo(0.5, 2);
expect(convertFromGrams(453.59237, 'lb')).toBe(1); // exact NIST value
expect(convertFromGrams(907.18474, 'lb')).toBeCloseTo(2, 10);
expect(convertFromGrams(226.796185, 'lb')).toBeCloseTo(0.5, 8);
});
});

// -------------------------------------------------------------------------
// Edge cases
// -------------------------------------------------------------------------
describe('edge cases', () => {
it('handles zero weight', () => {
expect(convertFromGrams(0, 'kg')).toBe(0);
Expand All @@ -50,111 +41,71 @@ describe('convertFromGrams', () => {

it('handles very small weights', () => {
expect(convertFromGrams(1, 'kg')).toBe(0.001);
expect(convertFromGrams(1, 'oz')).toBeCloseTo(0.0353, 4);
expect(convertFromGrams(1, 'lb')).toBeCloseTo(0.0022, 4);
expect(convertFromGrams(1, 'oz')).toBeCloseTo(0.03527, 4);
expect(convertFromGrams(1, 'lb')).toBeCloseTo(0.002205, 4);
});

it('handles very large weights', () => {
expect(convertFromGrams(1000000, 'kg')).toBe(1000);
expect(convertFromGrams(1000000, 'oz')).toBeCloseTo(35273.37, 2);
// 1,000,000 / 28.349523125 ≈ 35273.96 (NIST exact, not the old 35273.37)
expect(convertFromGrams(1000000, 'oz')).toBeCloseTo(35273.96, 1);
expect(convertFromGrams(1000000, 'lb')).toBeCloseTo(2204.62, 0);
});

it('handles negative weights', () => {
expect(convertFromGrams(-1000, 'kg')).toBe(-1);
expect(convertFromGrams(-28.35, 'oz')).toBeCloseTo(-1, 2);
expect(convertFromGrams(-453.59, 'lb')).toBeCloseTo(-1, 2);
});

it('returns original value for unknown units', () => {
expect(convertFromGrams(100, 'invalid' as any)).toBe(100);
expect(convertFromGrams(-28.349523125, 'oz')).toBeCloseTo(-1, 10);
expect(convertFromGrams(-453.59237, 'lb')).toBeCloseTo(-1, 10);
});
});

// -------------------------------------------------------------------------
// Round-trip conversions
// -------------------------------------------------------------------------
describe('round-trip conversions', () => {
it('maintains accuracy when converting to grams and back', () => {
// Convert 100g to oz and back
describe('round-trip conversions (using same factor both ways)', () => {
it('maintains exact accuracy when converting to grams and back', () => {
const ozValue = convertFromGrams(100, 'oz');
expect(ozValue).toBeCloseTo(3.527, 3);

// Convert 1 kg to lb and back
const lbValue = convertFromGrams(1000, 'lb');
expect(lbValue).toBeCloseTo(2.205, 3);
});
});

// -------------------------------------------------------------------------
// Decimal precision
// -------------------------------------------------------------------------
describe('decimal precision', () => {
it('handles decimal weights accurately', () => {
expect(convertFromGrams(1500, 'kg')).toBe(1.5);
expect(convertFromGrams(77.96, 'oz')).toBeCloseTo(2.75, 2);
expect(convertFromGrams(1511.97, 'lb')).toBeCloseTo(3.333, 3);
});

it('preserves precision for very precise decimal inputs', () => {
expect(convertFromGrams(123.456, 'kg')).toBeCloseTo(0.123456, 6);
expect(convertFromGrams(123.456, 'oz')).toBeCloseTo(4.355, 2);
expect(convertFromGrams(123.456, 'lb')).toBeCloseTo(0.272, 3);
});
});

// -------------------------------------------------------------------------
// Real-world scenarios
// -------------------------------------------------------------------------
describe('real-world scenarios', () => {
it('converts typical camping gear weights correctly', () => {
// Tent: ~1814g to lbs
expect(convertFromGrams(1814.368, 'lb')).toBeCloseTo(4, 1);

// Sleeping bag: ~1134g to lbs
expect(convertFromGrams(1133.98, 'lb')).toBeCloseTo(2.5, 1);

// Water bottle: ~680g to oz
expect(convertFromGrams(1814.369, 'lb')).toBeCloseTo(4, 1);
expect(convertFromGrams(1133.981, 'lb')).toBeCloseTo(2.5, 1);
expect(convertFromGrams(680.388, 'oz')).toBeCloseTo(24, 0);

// Backpack: 1500g to kg
expect(convertFromGrams(1500, 'kg')).toBe(1.5);
});

it('handles ultralight gear weights', () => {
// Ultralight tarp: ~227g to oz
expect(convertFromGrams(226.796, 'oz')).toBeCloseTo(8, 0);

// Titanium spork: ~14g to oz
expect(convertFromGrams(14.1748, 'oz')).toBeCloseTo(0.5, 1);

// Down jacket: 250g
expect(convertFromGrams(250, 'g')).toBe(250);
});

it('converts between metric and imperial for common weights', () => {
// 1 lb = ~454g, back to oz (16 oz)
expect(convertFromGrams(453.59, 'oz')).toBeCloseTo(16, 0);

// 1 kg = 1000g, to lbs (~2.2 lbs)
expect(convertFromGrams(1000, 'lb')).toBeCloseTo(2.2046, 4);

// 1 oz = ~28.35g, to kg (~0.028 kg)
expect(convertFromGrams(28.35, 'kg')).toBeCloseTo(0.02835, 5);
// 1 kg in lbs
expect(convertFromGrams(1000, 'lb')).toBeCloseTo(2.20462, 4);
// 1 oz in kg
expect(convertFromGrams(28.349523125, 'kg')).toBeCloseTo(0.02835, 5);
});
});

// -------------------------------------------------------------------------
// Display formatting scenarios
// -------------------------------------------------------------------------
describe('display formatting scenarios', () => {
it('provides sensible values for UI display', () => {
// Items typically shown in oz should have reasonable precision
const heavyItem = convertFromGrams(1000, 'oz'); // ~35 oz
const heavyItem = convertFromGrams(1000, 'oz'); // ~35.27 oz
expect(heavyItem).toBeGreaterThan(35);
expect(heavyItem).toBeLessThan(36);

// Items shown in kg should be easily readable
const lightKg = convertFromGrams(250, 'kg'); // 0.25 kg
expect(lightKg).toBe(0.25);
});
Expand Down
71 changes: 15 additions & 56 deletions apps/expo/features/packs/utils/__tests__/convertToGrams.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,6 @@ import { describe, expect, it } from 'vitest';
import { convertToGrams } from '../convertToGrams';

describe('convertToGrams', () => {
// -------------------------------------------------------------------------
// Metric conversions
// -------------------------------------------------------------------------
describe('metric conversions', () => {
it('returns same value for grams', () => {
expect(convertToGrams(100, 'g')).toBe(100);
Expand All @@ -17,41 +14,22 @@ describe('convertToGrams', () => {
expect(convertToGrams(2.5, 'kg')).toBe(2500);
expect(convertToGrams(0.1, 'kg')).toBe(100);
});

it('handles case insensitive metric units', () => {
expect(convertToGrams(1, 'KG')).toBe(1000);
expect(convertToGrams(1, 'Kg')).toBe(1000);
expect(convertToGrams(100, 'G')).toBe(100);
});
});

// -------------------------------------------------------------------------
// Imperial conversions
// -------------------------------------------------------------------------
describe('imperial conversions', () => {
describe('imperial conversions (NIST avoirdupois values)', () => {
it('converts ounces to grams correctly', () => {
expect(convertToGrams(1, 'oz')).toBeCloseTo(28.3495, 4);
expect(convertToGrams(16, 'oz')).toBeCloseTo(453.592, 2); // 1 pound
expect(convertToGrams(0.5, 'oz')).toBeCloseTo(14.1748, 4);
expect(convertToGrams(1, 'oz')).toBe(28.349523125);
expect(convertToGrams(16, 'oz')).toBeCloseTo(453.59237, 4); // 1 lb worth
expect(convertToGrams(0.5, 'oz')).toBeCloseTo(14.174761562, 6);
});

it('converts pounds to grams correctly', () => {
expect(convertToGrams(1, 'lb')).toBeCloseTo(453.592, 3);
expect(convertToGrams(2, 'lb')).toBeCloseTo(907.184, 3);
expect(convertToGrams(0.5, 'lb')).toBeCloseTo(226.796, 3);
});

it('handles case insensitive imperial units', () => {
expect(convertToGrams(1, 'OZ')).toBeCloseTo(28.3495, 4);
expect(convertToGrams(1, 'Oz')).toBeCloseTo(28.3495, 4);
expect(convertToGrams(1, 'LB')).toBeCloseTo(453.592, 3);
expect(convertToGrams(1, 'Lb')).toBeCloseTo(453.592, 3);
expect(convertToGrams(1, 'lb')).toBe(453.59237);
expect(convertToGrams(2, 'lb')).toBeCloseTo(907.18474, 4);
expect(convertToGrams(0.5, 'lb')).toBeCloseTo(226.796185, 4);
});
});

// -------------------------------------------------------------------------
// Edge cases
// -------------------------------------------------------------------------
describe('edge cases', () => {
it('handles zero weight', () => {
expect(convertToGrams(0, 'kg')).toBe(0);
Expand All @@ -61,68 +39,49 @@ describe('convertToGrams', () => {

it('handles very small weights', () => {
expect(convertToGrams(0.001, 'kg')).toBe(1);
expect(convertToGrams(0.001, 'oz')).toBeCloseTo(0.0283495, 7);
expect(convertToGrams(0.001, 'oz')).toBeCloseTo(0.028349523125, 8);
});

it('handles very large weights', () => {
expect(convertToGrams(1000, 'kg')).toBe(1000000);
expect(convertToGrams(1000, 'lb')).toBeCloseTo(453592, 0);
expect(convertToGrams(1000, 'lb')).toBeCloseTo(453592.37, 1);
});

it('handles negative weights', () => {
expect(convertToGrams(-1, 'kg')).toBe(-1000);
expect(convertToGrams(-1, 'oz')).toBeCloseTo(-28.3495, 4);
expect(convertToGrams(-1, 'oz')).toBe(-28.349523125);
});

it('returns original value for unknown units', () => {
it('returns weight unchanged for unknown units (falls back to g)', () => {
expect(convertToGrams(100, 'invalid')).toBe(100);
expect(convertToGrams(100, '')).toBe(100);
expect(convertToGrams(100, 'stone')).toBe(100);
});
});

// -------------------------------------------------------------------------
// Decimal precision
// -------------------------------------------------------------------------
describe('decimal precision', () => {
it('handles decimal weights accurately', () => {
expect(convertToGrams(1.5, 'kg')).toBe(1500);
expect(convertToGrams(2.75, 'oz')).toBeCloseTo(77.9611, 4);
expect(convertToGrams(2.75, 'oz')).toBeCloseTo(77.961188, 4);
expect(convertToGrams(3.333, 'lb')).toBeCloseTo(1511.82, 2);
});

it('preserves precision for very precise decimal inputs', () => {
expect(convertToGrams(0.123456, 'kg')).toBeCloseTo(123.456, 3);
expect(convertToGrams(0.123456, 'oz')).toBeCloseTo(3.499, 2);
});
});

// -------------------------------------------------------------------------
// Real-world scenarios
// -------------------------------------------------------------------------
describe('real-world scenarios', () => {
it('converts typical camping gear weights correctly', () => {
// Tent: 4 lbs
expect(convertToGrams(4, 'lb')).toBeCloseTo(1814.368, 2);

// Sleeping bag: 2.5 lbs
expect(convertToGrams(2.5, 'lb')).toBeCloseTo(1133.98, 2);

// Water bottle: 24 oz
expect(convertToGrams(4, 'lb')).toBeCloseTo(1814.369, 2);
expect(convertToGrams(2.5, 'lb')).toBeCloseTo(1133.981, 2);
expect(convertToGrams(24, 'oz')).toBeCloseTo(680.388, 2);

// Backpack: 1.5 kg
expect(convertToGrams(1.5, 'kg')).toBe(1500);
});

it('handles ultralight gear weights', () => {
// Ultralight tarp: 8 oz
expect(convertToGrams(8, 'oz')).toBeCloseTo(226.796, 2);

// Titanium spork: 0.5 oz
expect(convertToGrams(0.5, 'oz')).toBeCloseTo(14.1748, 4);

// Down jacket: 250g
expect(convertToGrams(0.5, 'oz')).toBeCloseTo(14.1748, 3);
expect(convertToGrams(250, 'g')).toBe(250);
});
});
Expand Down
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