feat(units): Add Ah unit

docs/datatypes/units.md

@@ -318,7 +318,7 @@ Force               | newton (N), dyne (dyn), poundforce (lbf), kip
 Energy              | joule (J), erg, Wh, BTU, electronvolt (eV)
 Power               | watt (W), hp
 Pressure            | Pa, psi, atm, torr, bar, mmHg, mmH2O, cmH2O
-Electricity and magnetism | ampere (A), coulomb (C), watt (W), volt (V), ohm, farad (F), weber (Wb), tesla (T), henry (H), siemens (S), electronvolt (eV)
+Electricity and magnetism | ampere (A), ampere-hour (Ah), coulomb (C), watt (W), volt (V), ohm, farad (F), weber (Wb), tesla (T), henry (H), siemens (S), electronvolt (eV)
 Binary              | bits (b), bytes (B)
 
 Note: all time units are based on the Julian year, with one month being 1/12th of a Julian year, a year being one Julian year, a decade being 10 Julian years, a century being 100, and a millennium being 1000.

src/type/unit/Unit.js

@@ -2660,6 +2660,13 @@ export const createUnitClass = /* #__PURE__ */ factory(name, dependencies, ({
       value: 1,
       offset: 0
     },
+    Ah: {
+      name: 'Ah',
+      base: BASE_UNITS.ELECTRIC_CHARGE,
+      prefixes: PREFIXES.SHORT,
+      value: 3600,
+      offset: 0
+    },
     // Electric capacitance
     farad: {
       name: 'farad',

test/unit-tests/type/unit/Unit.test.js

@@ -67,6 +67,13 @@ describe('Unit', function () {
       assert.strictEqual(unit1.units[0].unit.name, 'm3')
     })
 
+    it('should create ampere-hour correctly', function () {
+      const n = 1.4
+      const unit1 = new Unit(n, 'Ah')
+      assert.strictEqual(unit1.value, n * 3600)
+      assert.strictEqual(unit1.units[0].unit.name, 'Ah')
+    })
+
     it('should create a unit from an existing unit', function () {
       const unit1 = new Unit(null, 'm/s^2')
       const unit2 = new Unit(5, unit1)
@@ -1070,6 +1077,28 @@ describe('Unit', function () {
       assert.strictEqual(unit1.pow(2).skipAutomaticSimplification, false)
     })
 
+    it('should be able to combine A and h into Ah', function () {
+      // by default, this stays Ah, due to the default unit system
+      const n1 = 2
+      const n2 = 3
+      const unit1 = new Unit(n1, 'A')
+      const unit2 = new Unit(n2, 'h')
+      const unitM = unit1.multiply(unit2).simplify()
+      assert.strictEqual(unitM.units[0].unit.name, 'Ah')
+      assert.strictEqual(unitM.value, n1 * n2 * 3600)
+    })
+
+    it('should be able to combine W and h into J', function () {
+      // by default, this converts to J, due to the default unit system using J for ENERGY
+      const n1 = 2
+      const n2 = 3
+      const unit1 = new Unit(n1, 'W')
+      const unit2 = new Unit(n2, 'h')
+      const unitM = unit1.multiply(unit2).simplify()
+      assert.strictEqual(unitM.units[0].unit.name, 'J')
+      assert.strictEqual(unitM.value, n1 * n2 * 3600)
+    })
+
     it('should retain the units of their operands without simplifying', function () {
       const unit1 = new Unit(10, 'N/s')
       const unit2 = new Unit(10, 'h')