patch removed util methods for vows (#389)

package.json

@@ -89,7 +89,7 @@
     "version": "genversion --es6 lib/version.ts && git add lib/version.ts",
     "test": "npm run test:ts && npm run test:legacy",
     "test:ts": "jest",
-    "test:legacy": "npm run build -- --declaration false && vows test/*_test.js",
+    "test:legacy": "npm run build -- --declaration false && ./test/scripts/vows.js test/*_test.js",
     "typecheck": "tsc --noEmit",
     "cover": "jest --coverage",
     "eslint": "eslint --env node --ext .ts .",

test/scripts/vows.js

@@ -0,0 +1,15 @@
+#!/usr/bin/env node
+/**
+ * @fileoverview Vows logs using methods from `util` that were removed in node v12. To avoid cryptic
+ * error messages when tests fail, we patch those methods using `console.log`.
+ * @see {@link https://nodejs.org/api/deprecations.html#DEP0026|`util.print` deprecation}
+ * @see {@link https://nodejs.org/api/deprecations.html#DEP0027|`util.puts` deprecation}
+ * @see {@link https://nodejs.org/docs/latest-v0.10.x/api/util.html|Docs for deprecated `util` methods}
+ */
+
+// Patch deprecated util methods
+const util = require("node:util");
+util.print = (...args) => console.log(args.join(''));
+util.puts = (...args) => console.log(args.join('\n'));
+// Call vows executable
+require("vows/bin/vows");