fix bypass test, minor change to docs, move bypass logic after serving the /metrics route, see MR #70

README.md

@@ -52,7 +52,7 @@ Which labels to include in `http_request_duration_seconds` metric:
 * **includeUp**: include an auxiliary "up"-metric which always returns 1, default: **true**
 * **metricsPath**: replace the `/metrics` route with a **regex** or exact **string**. Note: it is highly recommended to just stick to the default
 * **metricType**: histogram/summary selection. See more details below
-* **bypass**: Function which takes express request as an argument. Determines whether the given request should be included in the metrics or not, default: **() => false**
+* **bypass**: function taking express request as an argument and determines whether the given request should be excluded in the metrics, default: **() => false**
 
 ### metricType option ###
 

spec/index.spec.js

@@ -204,12 +204,15 @@ describe('index', () => {
     const app = express();
     const instance = bundle({
       bypass: (req)=> {
-        return ['/test', /bad.word/].includes(req.url)
+        // metrics added here to attempt skipping /metrics
+        // this should fail though, because serving /metrics preceeds bypassing
+        return !!req.url.match(/test|bad.word|metrics/)
       }
     });
     app.use(instance);
     app.use('/test', (req, res) => res.send('it worked'));
     app.use('/some/bad-word', (req, res) => res.send('it worked too'));
+    app.use('/good-word', (req, res) => res.send('this will be counted'));
     const agent = supertest(app);
     agent
       .get('/test')
@@ -217,14 +220,21 @@ describe('index', () => {
         agent
           .get('/some/bad-word')
           .end(() => {
-            const metricHashMap = instance.metrics.http_request_duration_seconds.hashMap;
-            expect(metricHashMap['status_code:200']).not.toBeDefined();
-
             agent
-              .get('/metrics')
-              .end((err, res) => {
-                expect(res.status).toBe(200);
-                done();
+              .get('/good-word')
+              .end(() => {
+                const metricHashMap = instance.metrics.http_request_duration_seconds.hashMap;
+                expect(metricHashMap['status_code:200']).toBeDefined();
+
+                // only /good-word should be counted
+                expect(metricHashMap['status_code:200'].count).toBe(1);
+
+                agent
+                  .get('/metrics')
+                  .end((err, res) => {
+                    expect(res.status).toBe(200);
+                    done();
+                  });
               });
           });
       });

src/index.js

@@ -131,16 +131,18 @@ function main(opts) {
     : new RegExp('^' + (opts.metricsPath || '/metrics') + '/?$');
 
   const middleware = function (req, res, next) {
-    if (opts.bypass && opts.bypass(req)) {
-      return next();
-    }
-
     const path = req.originalUrl || req.url; // originalUrl gets lost in koa-connect?
 
     if (opts.autoregister && path.match(metricsMatch)) {
         return metricsMiddleware(req, res);
     }
 
+    // bypass() is checked only after /metrics was processed
+    // if you wish to disable /metrics use autoregister:false instead
+    if (opts.bypass && opts.bypass(req)) {
+      return next();
+    }
+
     if (opts.excludeRoutes && matchVsRegExps(path, opts.excludeRoutes)) {
       return next();
     }