fixed bug in resolving ip version in dynamic upstreams (#6448)

modules/caddyhttp/reverseproxy/upstreams_test.go

@@ -0,0 +1,56 @@
+package reverseproxy
+
+import "testing"
+
+func TestResolveIpVersion(t *testing.T) {
+	falseBool := false
+	trueBool := true
+	tests := []struct {
+		Versions          *IPVersions
+		expectedIpVersion string
+	}{
+		{
+			Versions:          &IPVersions{IPv4: &trueBool},
+			expectedIpVersion: "ip4",
+		},
+		{
+			Versions:          &IPVersions{IPv4: &falseBool},
+			expectedIpVersion: "ip",
+		},
+		{
+			Versions:          &IPVersions{IPv4: &trueBool, IPv6: &falseBool},
+			expectedIpVersion: "ip4",
+		},
+		{
+			Versions:          &IPVersions{IPv6: &trueBool},
+			expectedIpVersion: "ip6",
+		},
+		{
+			Versions:          &IPVersions{IPv6: &falseBool},
+			expectedIpVersion: "ip",
+		},
+		{
+			Versions:          &IPVersions{IPv6: &trueBool, IPv4: &falseBool},
+			expectedIpVersion: "ip6",
+		},
+		{
+			Versions:          &IPVersions{},
+			expectedIpVersion: "ip",
+		},
+		{
+			Versions:          &IPVersions{IPv4: &trueBool, IPv6: &trueBool},
+			expectedIpVersion: "ip",
+		},
+		{
+			Versions:          &IPVersions{IPv4: &falseBool, IPv6: &falseBool},
+			expectedIpVersion: "ip",
+		},
+	}
+	for _, test := range tests {
+		ipVersion := resolveIpVersion(test.Versions)
+		if ipVersion != test.expectedIpVersion {
+			t.Errorf("resolveIpVersion(): Expected %s got %s", test.expectedIpVersion, ipVersion)
+		}
+	}
+
+}