config: ensure ignored status codes are numbers

lib/config.js

@@ -198,7 +198,10 @@ function Config(config) {
   // 4. override config with environment variables
   this._fromEnvironment();
 
-  // 5. put the version in the config
+  // 5. clean up anything that requires postprocessing
+  this._canonicalize();
+
+  // 6. put the version in the config
   this.version = require(path.join(__dirname, '..', 'package.json')).version;
 }
 util.inherits(Config, EventEmitter);
@@ -564,6 +567,21 @@ Config.prototype._fromEnvironment = function (metadata, data) {
   }, this);
 };
 
+/**
+ * Depending on how the status codes are set, they could be strings, which
+ * makes strict equality testing / indexOf fail. To keep things cheap, parse
+ * them once, after configuration has finished loading. Other one-off shims
+ * based on special properties of configuration values should go here as well.
+ */
+Config.prototype._canonicalize = function () {
+  var codes = this.error_collector && this.error_collector.ignore_status_codes;
+  if (codes) {
+    this.error_collector.ignore_status_codes = codes.map(function (code) {
+      return parseInt(code, 10);
+    });
+  }
+};
+
 /**
  * The agent will use the supportability metrics object if it's
  * available.

test/config.test.js

@@ -155,7 +155,7 @@ describe("the agent configuration", function () {
       idempotentEnv('NEW_RELIC_ERROR_COLLECTOR_IGNORE_ERROR_CODES',
                     '401,404,502', function (tc) {
         should.exist(tc.error_collector.ignore_status_codes);
-        expect(tc.error_collector.ignore_status_codes).eql(['401', '404', '502']);
+        expect(tc.error_collector.ignore_status_codes).eql([401, 404, 502]);
       });
     });