updated unit tests

pkg/metrics/metrics_test.go

@@ -173,3 +173,83 @@ var _ = Describe("Metrics Server", func() {
 		Expect(string(body)).To(ContainSubstring(`custom_metric_total 42`))
 	})
 })
+
+var _ = Describe("Metrics Server Functions", func() {
+	var listener net.Listener
+	var addr string
+
+	AfterEach(func() {
+		// Ensure the listener is closed after each test
+		if listener != nil {
+			_ = listener.Close()
+		}
+	})
+
+	Describe("StartMetricsServer", func() {
+		It("should start the server successfully with a valid address", func() {
+			// Start the server
+			addr = "127.0.0.1:0" // Dynamic port
+			server, err := metrics.StartMetricsServer(addr)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(server).NotTo(BeNil())
+
+			// Use the actual address from the server
+			resp, err := http.Get(fmt.Sprintf("http://%s%s", server.Addr, constants.MetricsPath))
+			Expect(err).NotTo(HaveOccurred())
+			Expect(resp.StatusCode).To(Equal(http.StatusOK))
+			Expect(resp.Body.Close()).To(Succeed())
+
+			// Clean up
+			_ = server.Close()
+		})
+
+		It("should return an error when failing to listen on the address", func() {
+			addr = "invalid_address"
+			server, err := metrics.StartMetricsServer(addr)
+			Expect(err).To(HaveOccurred())
+			Expect(server).To(BeNil())
+		})
+	})
+
+	Describe("StartMetricsServerWithListener", func() {
+		It("should start the server successfully with a valid listener", func() {
+			// Create a valid listener
+			var err error
+			listener, err = net.Listen("tcp", "127.0.0.1:0")
+			Expect(err).NotTo(HaveOccurred())
+
+			server, err := metrics.StartMetricsServerWithListener(listener)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(server).NotTo(BeNil())
+
+			resp, err := http.Get(fmt.Sprintf("http://%s%s", listener.Addr().String(), constants.MetricsPath))
+			Expect(err).NotTo(HaveOccurred())
+			Expect(resp.StatusCode).To(Equal(http.StatusOK))
+			Expect(resp.Body.Close()).To(Succeed())
+
+			// Clean up
+			_ = server.Close()
+		})
+
+		It("should handle errors during server operation gracefully", func() {
+			// Create a valid listener
+			var err error
+			listener, err = net.Listen("tcp", "127.0.0.1:0")
+			Expect(err).NotTo(HaveOccurred())
+
+			// Start the server
+			server, err := metrics.StartMetricsServerWithListener(listener)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(server).NotTo(BeNil())
+
+			// Close the listener to simulate an error during `srv.Serve`
+			_ = listener.Close()
+
+			// Wait briefly to ensure the goroutine handling `srv.Serve` runs
+			time.Sleep(100 * time.Millisecond)
+
+			// Clean up
+			_ = server.Close()
+		})
+	})
+})