Add tests for "globalURL" template function.

web/web_test.go

@@ -0,0 +1,56 @@
+package web
+
+import (
+	"net/url"
+	"testing"
+)
+
+func TestGlobalURL(t *testing.T) {
+	opts := &Options{
+		ListenAddress: ":9090",
+		ExternalURL: &url.URL{
+			Scheme: "https",
+			Host:   "externalhost:80",
+			Path:   "/path/prefix",
+		},
+	}
+
+	tests := []struct {
+		inURL  string
+		outURL string
+	}{
+		{
+			// Nothing should change if the input URL is not on localhost, even if the port is our listening port.
+			inURL:  "http://somehost:9090/metrics",
+			outURL: "http://somehost:9090/metrics",
+		},
+		{
+			// Port and host should change if target is on localhost and port is our listening port.
+			inURL:  "http://localhost:9090/metrics",
+			outURL: "https://externalhost:80/metrics",
+		},
+		{
+			// Only the host should change if the port is not our listening port, but the host is localhost.
+			inURL:  "http://localhost:8000/metrics",
+			outURL: "http://externalhost:8000/metrics",
+		},
+		{
+			// Alternative localhost representations should also work.
+			inURL:  "http://127.0.0.1:9090/metrics",
+			outURL: "https://externalhost:80/metrics",
+		},
+	}
+
+	for i, test := range tests {
+		inURL, err := url.Parse(test.inURL)
+		if err != nil {
+			t.Fatalf("%d. Error parsing input URL: %s", i, err)
+		}
+		globalURL := tmplFuncs("", opts)["globalURL"].(func(u *url.URL) *url.URL)
+		outURL := globalURL(inURL)
+
+		if outURL.String() != test.outURL {
+			t.Fatalf("%d. got %s, want %s", i, outURL.String(), test.outURL)
+		}
+	}
+}