Function ScrapeAndCompare

prometheus/testutil/testutil.go:166–189

ScrapeAndCompare calls a remote exporter's endpoint which is expected to return some metrics in plain text format. Then it compares it with the results that the `expected` would return. If the `metricNames` is not empty it would filter the comparison only to the given metric names. NOTE: Be mindful

(url string, expected io.Reader, metricNames ...string)

// NOTE: Be mindful of accidental discrepancies between expected and metricNames; metricNames filter
// both expected and scraped metrics. See https://github.com/prometheus/client_golang/issues/1351.
func ScrapeAndCompare(url string, expected io.Reader, metricNames ...string) error {
	resp, err := http.Get(url)
	if err != nil {
		return fmt.Errorf("scraping metrics failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("the scraping target returned a status code other than 200: %d",
			resp.StatusCode)
	}

	scraped, err := convertReaderToMetricFamily(resp.Body)
	if err != nil {
		return err
	}

	wanted, err := convertReaderToMetricFamily(expected)
	if err != nil {
		return err
	}

	return compareMetricFamilies(scraped, wanted, metricNames...)
}

// CollectAndCompare collects the metrics identified by `metricNames` and compares them in the Prometheus text
// exposition format to the data read from expected.