Make Android UDP log forwarding opt-in with a persisted target

tools/chatgui-android/app/src/test/java/com/utun/chat/data/UdpLogSettingsTest.kt

@@ -0,0 +1,40 @@
+package com.utun.chat.data
+
+import org.junit.Assert.*
+import org.junit.Test
+
+class UdpLogSettingsTest {
+    private fun config(settings: UdpLogSettings): String = buildString { appendLine("[global]"); settings.appendConfig(this) }
+
+    @Test fun defaultAddressDoesNotEnableNetworkLogging() {
+        val settings = UdpLogSettings()
+        assertFalse(settings.enabled)
+        assertFalse(settings.active)
+        assertEquals("[global]\n", config(settings))
+    }
+
+    @Test fun explicitEnableWritesTargetIntoStartupConfig() {
+        val settings = UdpLogSettings(true, "192.168.40.250", 9999)
+        assertTrue(settings.active)
+        assertEquals("[global]\n\n[log_udp]\nip=192.168.40.250\nport=9999\n", config(settings))
+    }
+
+    @Test fun disabledTargetRetainsAddressWithoutConfiguringSender() {
+        val enabled = UdpLogSettings(true, "10.20.30.40", 12345)
+        val disabled = enabled.copy(enabled = false)
+        assertEquals(enabled.ip, disabled.ip)
+        assertEquals(enabled.port, disabled.port)
+        assertEquals("[global]\n", config(disabled))
+        assertEquals(config(enabled), config(disabled.copy(enabled = true)))
+    }
+
+    @Test fun malformedTargetsNeverEnableSender() {
+        for (ip in listOf("", "localhost", "127.1", "1.2.3.256", "01.2.3.4", "1.2.3.4 ")) {
+            val settings = UdpLogSettings(true, ip, 9999)
+            assertFalse(ip, settings.active)
+            assertEquals("[global]\n", config(settings))
+        }
+        for (port in listOf(-1, 0, 65536)) assertFalse(UdpLogSettings(true, "127.0.0.1", port).active)
+        assertTrue(UdpLogSettings(true, "127.0.0.1", 65535).active)
+    }
+}