refactor: create test/utils

test/utils/wtfnode.ts

@@ -0,0 +1,35 @@
+import * as util from "util"
+import * as wtfnode from "wtfnode"
+
+// Jest seems to hijack console.log in a way that makes the output difficult to
+// read. So we'll write directly to process.stderr instead.
+const write = (...args: [any, ...any]) => {
+  if (args.length > 0) {
+    process.stderr.write(util.format(...args) + "\n")
+  }
+}
+wtfnode.setLogger("info", write)
+wtfnode.setLogger("warn", write)
+wtfnode.setLogger("error", write)
+
+let active = false
+
+/**
+ * Start logging open handles periodically. This can be used to see what is
+ * hanging open if anything.
+ */
+export function setup(): void {
+  if (active) {
+    return
+  }
+  active = true
+
+  const interval = 5000
+  const wtfnodeDump = () => {
+    wtfnode.dump()
+    const t = setTimeout(wtfnodeDump, interval)
+    t.unref()
+  }
+  const t = setTimeout(wtfnodeDump, interval)
+  t.unref()
+}