added unit testing, and started implementing unit tests...phew

node_modules/node-environment-flags/implementation.js

@@ -0,0 +1,62 @@
+'use strict';
+
+const semver = require('semver');
+const flags = require('./flags.json');
+const getDescriptors = require('object.getownpropertydescriptors');
+
+const replaceUnderscoresRegex = /_/g;
+const leadingDashesRegex = /^--?/;
+const trailingValuesRegex = /=.*$/;
+
+const replace = Function.call.bind(String.prototype.replace);
+const has = Function.call.bind(Set.prototype.has);
+const test = Function.call.bind(RegExp.prototype.test);
+
+const [allowedNodeEnvironmentFlags, detectedSemverRange] = Object.keys(
+  flags
+).reduce(
+  (acc, range) =>
+    acc ||
+    (semver.satisfies(process.version, range) ? [flags[range], range] : acc),
+  null
+);
+
+const trimLeadingDashes = flag => replace(flag, leadingDashesRegex, '');
+
+class NodeEnvironmentFlagsSet extends Set {
+  constructor(...args) {
+    super(...args);
+
+    this.add = () => this;
+  }
+
+  delete() {
+    return false;
+  }
+
+  clear() {}
+
+  has(key) {
+    if (typeof key === 'string') {
+      key = replace(key, replaceUnderscoresRegex, '-');
+      if (test(leadingDashesRegex, key)) {
+        key = replace(key, trailingValuesRegex, '');
+        return has(this, key);
+      }
+      return has(nodeFlags, key);
+    }
+    return false;
+  }
+}
+const nodeFlags = Object.defineProperties(
+  new Set(allowedNodeEnvironmentFlags.map(trimLeadingDashes)),
+  getDescriptors(Set.prototype)
+);
+
+Object.freeze(NodeEnvironmentFlagsSet.prototype.constructor);
+Object.freeze(NodeEnvironmentFlagsSet.prototype);
+
+exports.allowedNodeEnvironmentFlags = Object.freeze(
+  new NodeEnvironmentFlagsSet(allowedNodeEnvironmentFlags)
+);
+exports.detectedSemverRange = detectedSemverRange;