Function testReflectedProperty

src/test/reflectPropertiesHelper.ts:15–53

(propertyPair: PropertyPair, overrideValueToTest: string | boolean | number | null = null)

}

export function testReflectedProperty(propertyPair: PropertyPair, overrideValueToTest: string | boolean | number | null = null) {
  const propertyName = Object.keys(propertyPair)[0];
  const defaultValue = propertyPair[propertyName][0];
  const attributeName = propertyPair[propertyName][1] || propertyName.toLowerCase();
  const keywords = propertyPair[propertyName][2];
  const valueToTest = deriveValueToTest(overrideValueToTest !== null ? overrideValueToTest : defaultValue);

  test(`${propertyName} should be ${defaultValue} by default`, (t) => {
    const { element } = t.context;
    t.is(element[propertyName], defaultValue);
  });

  test(`${propertyName} should be settable to a single value`, (t) => {
    const { element } = t.context;
    element[propertyName] = valueToTest;
    t.is(element[propertyName], valueToTest);
  });

  test(`${propertyName} property change should be reflected in attribute`, (t) => {
    const { element } = t.context;
    element[propertyName] = valueToTest;
    if (keywords) {
      // Enumerated attrs have keywords instead of 'true' and 'false', e.g. translate="yes|no".
      const keyword = valueToTest ? keywords[0] : keywords[1];
      t.is(element.getAttribute(attributeName), keyword);
    } else if (typeof valueToTest === 'boolean') {
      // Boolean attributes only care about existence of the attribute, not their values.
      t.is(element.hasAttribute(attributeName), valueToTest);
    } else {
      t.is(element.getAttribute(attributeName), String(valueToTest));
    }
  });

  test(`${propertyName} attribute change should be reflected in property`, (t) => {
    const { element } = t.context;
    element.setAttribute(attributeName, String(valueToTest));
    t.is(element[propertyName], valueToTest);
  });
}

function deriveValueToTest(valueToTest: string | boolean | number): string | boolean | number {
  switch (typeof valueToTest) {