es.number.to-precision.js

QUnit.test('Number#toPrecision', assert => {
  const { toPrecision } = Number.prototype;
  assert.isFunction(toPrecision);
  assert.name(toPrecision, 'toPrecision');
  assert.arity(toPrecision, 1);
  assert.looksNative(toPrecision);
  assert.nonEnumerable(Number.prototype, 'toPrecision');
  assert.same(0.00008.toPrecision(3), '0.0000800', '0.00008.toPrecision(3)');
  assert.same(1.255.toPrecision(2), '1.3', '1.255.toPrecision(2)');
  assert.same(1843654265.0774949.toPrecision(13), '1843654265.077', '1843654265.0774949.toPrecision(13)');
  assert.same(NaN.toPrecision(1), 'NaN', 'If x is NaN, return the String "NaN".');
  assert.same(123.456.toPrecision(), '123.456', 'If precision is undefined, return ! ToString(x).');
  assert.same(123.456.toPrecision(undefined), '123.456', 'If precision is undefined, return ! ToString(x).');
  assert.throws(() => 0.9.toPrecision(0), RangeError, 'If p < 1 or p > 21, throw a RangeError exception.');
  assert.throws(() => 0.9.toPrecision(101), RangeError, 'If p < 1 or p > 21, throw a RangeError exception.');
  assert.throws(() => toPrecision.call({}, 1), TypeError, '? thisNumberValue(this value)');
  assert.throws(() => toPrecision.call('123', 1), TypeError, '? thisNumberValue(this value)');
  assert.throws(() => toPrecision.call(false, 1), TypeError, '? thisNumberValue(this value)');
  assert.throws(() => toPrecision.call(null, 1), TypeError, '? thisNumberValue(this value)');
  assert.throws(() => toPrecision.call(undefined, 1), TypeError, '? thisNumberValue(this value)');
});