Update test framework: fix run_tests.py to support all test files, add auto-import-check for test files

node_modules/prom-client/lib/metrics/processOpenFileDescriptors.js

@@ -0,0 +1,36 @@
+'use strict';
+
+const Gauge = require('../gauge');
+const fs = require('fs');
+const process = require('process');
+
+const PROCESS_OPEN_FDS = 'process_open_fds';
+
+module.exports = (registry, config = {}) => {
+	if (process.platform !== 'linux') {
+		return;
+	}
+
+	const namePrefix = config.prefix ? config.prefix : '';
+	const labels = config.labels ? config.labels : {};
+	const labelNames = Object.keys(labels);
+
+	new Gauge({
+		name: namePrefix + PROCESS_OPEN_FDS,
+		help: 'Number of open file descriptors.',
+		registers: registry ? [registry] : undefined,
+		labelNames,
+		collect() {
+			try {
+				const fds = fs.readdirSync('/proc/self/fd');
+				// Minus 1 to not count the fd that was used by readdirSync(),
+				// it's now closed.
+				this.set(labels, fds.length - 1);
+			} catch {
+				// noop
+			}
+		},
+	});
+};
+
+module.exports.metricNames = [PROCESS_OPEN_FDS];