Merge pull request #8 from Goodluckhf/self-metrics

fix: add '_' if prefix options provided

src/UMetrics.js

@@ -58,20 +58,26 @@ class UMetrics {
    */
   start() {
     if (this.nodejsMetricsEnabled) {
-      this.enableExportingDefaultMetrics();
+      this.enableExportingDefaultMetrics(this.prefix && `${this.prefix}_`);
     }
     this.transport.start();
     return this;
   }
 
   /**
+   * @param {String} prefix
    * @private
    */
-  enableExportingDefaultMetrics() {
-    promClient.collectDefaultMetrics({
-      prefix: this.prefix,
+  enableExportingDefaultMetrics(prefix) {
+    const options = {
       timeout: this.nodejsMetricsInterval,
-    });
+    };
+
+    if (prefix) {
+      options.prefix = prefix;
+    }
+
+    promClient.collectDefaultMetrics(options);
   }
 }
 

src/UMetrics.server.test.js

@@ -86,4 +86,35 @@ describe('UMetrics facade', () => {
     uMetrics.start();
     expect(calledCount).to.be.equals(0);
   });
+
+  it('Should add _ if prefix option provided', () => {
+    let expectedPrefix = null;
+    const uMetrics = new UMetrics(new Transport(), {
+      port: 1111,
+      nodejsMetricsEnabled: true,
+      prefix: 'test',
+    });
+
+    uMetrics.enableExportingDefaultMetrics = prefix => {
+      expectedPrefix = prefix;
+    };
+
+    uMetrics.start();
+    expect(expectedPrefix).to.be.equals('test_');
+  });
+
+  it('Should call enableExportMetrics without parameters if prefix is not provided', () => {
+    let expectedPrefix = 0;
+    const uMetrics = new UMetrics(new Transport(), {
+      port: 1111,
+      nodejsMetricsEnabled: true,
+    });
+
+    uMetrics.enableExportingDefaultMetrics = prefix => {
+      expectedPrefix = prefix;
+    };
+
+    uMetrics.start();
+    expect(expectedPrefix).to.be.null;
+  });
 });