Add tests for mustParseAddress

internal/badgateway/roundtripper.go

@@ -53,16 +53,20 @@ func NewRoundTripper(backend *url.URL, socket string, proxyHeadersTimeout time.D
 }
 
 func mustParseAddress(address, scheme string) string {
-	if host, port, err := net.SplitHostPort(address); err == nil {
+	if scheme == "https" {
+		panic("TLS is not supported for backend connections")
+	}
+
+	if host, port, err := net.SplitHostPort(address); err == nil && host != "" && port != "" {
 		return host + ":" + port
 	}
 
 	address = address + ":" + scheme
-	if host, port, err := net.SplitHostPort(address); err == nil {
+	if host, port, err := net.SplitHostPort(address); err == nil && host != "" && port != "" {
 		return host + ":" + port
 	}
 
-	panic("could not parse host/port from  addres / scheme")
+	panic("could not parse host:port from address and scheme")
 }
 
 func (t *RoundTripper) RoundTrip(r *http.Request) (res *http.Response, err error) {

internal/badgateway/roundtripper_test.go

+package badgateway
+
+import (
+	"log"
+	"testing"
+)
+
+func TestMustParseAddress(t *testing.T) {
+	successExamples := []struct{ address, scheme, expected string }{
+		{"1.2.3.4:56", "http", "1.2.3.4:56"},
+		{"[::1]:23", "http", "::1:23"},
+		{"4.5.6.7", "http", "4.5.6.7:http"},
+	}
+	for _, example := range successExamples {
+		result := mustParseAddress(example.address, example.scheme)
+		if example.expected != result {
+			t.Errorf("expected %q, got %q", example.expected, result)
+		}
+	}
+
+	panicExamples := []struct{ address, scheme string }{
+		{"1.2.3.4", ""},
+		{"1.2.3.4", "https"},
+	}
+
+	for _, panicExample := range panicExamples {
+		func() {
+			defer func() {
+				if r := recover(); r == nil {
+					t.Errorf("expected panic for %v but none occurred", panicExample)
+				}
+			}()
+			log.Print(mustParseAddress(panicExample.address, panicExample.scheme))
+		}()
+	}
+}