Оверинжиниринг головного мозга

interface Measurement {
	date: Date;
	value: number;
}

interface Response {
	airTemperatures: Measurement[];
	waterTemperatures: Measurement[];
}

export class SimpleDate {
	constructor(private date: Date) {}

	/** Returns date in `DD.MM.YYYY` format  */
	toString(): string {
		return `${this.date.getDate()}.${this.date.getMonth() + 1}.${this.date.getFullYear()}`;
	}
}

async function getMeasurements(from: SimpleDate, to: SimpleDate): Promise<Response> {
	return {
		airTemperatures: await getAirTemperatureMeasurements(from, to),
		waterTemperatures: await getWaterTemperatureMeasurements(from, to),
	};
}

async function getAirTemperatureMeasurements(
	from: SimpleDate,
	to: SimpleDate,
): Promise<Measurement[]> {
	return parseMeasurements(await getHtmlContent(`/air-temperature?from=${from}&to=${to}`));
}

// Покрываем тестами вида "html" -> Measurements[]
// Для специфичных форматов будем создавать подобные парсеры
function parseMeasurements(html: string): Measurement[] {
	return []; // not implemented
}

async function getHtmlContent(url: string): Promise<string> {
	return 'html...'; // not implemented
}

async function getWaterTemperatureMeasurements(
	from: SimpleDate,
	to: SimpleDate,
): Promise<Measurement[]> {
	return parseMeasurements(await getHtmlContent(`/water-temperature?from=${from}&to=${to}`));
}

А как вы нагрешили в код?