feat(test): Add comprehensive unit and instrumentation tests (#4260)

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

app/src/test/java/com/geeksville/mesh/service/PacketHandlerTest.kt

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.geeksville.mesh.service
+
+import com.geeksville.mesh.repository.radio.RadioInterfaceService
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.verify
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.runTest
+import org.junit.Before
+import org.junit.Test
+import org.meshtastic.core.data.repository.MeshLogRepository
+import org.meshtastic.core.data.repository.PacketRepository
+import org.meshtastic.core.service.ConnectionState
+import org.meshtastic.proto.MeshProtos
+
+class PacketHandlerTest {
+
+    private val packetRepository: PacketRepository = mockk(relaxed = true)
+    private val serviceBroadcasts: MeshServiceBroadcasts = mockk(relaxed = true)
+    private val radioInterfaceService: RadioInterfaceService = mockk(relaxed = true)
+    private val meshLogRepository: MeshLogRepository = mockk(relaxed = true)
+    private val connectionStateHolder: ConnectionStateHandler = mockk(relaxed = true)
+
+    private val testDispatcher = StandardTestDispatcher()
+    private val testScope = TestScope(testDispatcher)
+
+    private lateinit var handler: PacketHandler
+
+    @Before
+    fun setUp() {
+        handler =
+            PacketHandler(
+                dagger.Lazy { packetRepository },
+                serviceBroadcasts,
+                radioInterfaceService,
+                dagger.Lazy { meshLogRepository },
+                connectionStateHolder,
+            )
+        handler.start(testScope)
+    }
+
+    @Test
+    fun `sendToRadio with ToRadio Builder sends immediately`() {
+        val builder =
+            MeshProtos.ToRadio.newBuilder().apply { packet = MeshProtos.MeshPacket.newBuilder().setId(123).build() }
+
+        handler.sendToRadio(builder)
+
+        verify { radioInterfaceService.sendToRadio(any()) }
+        // Verify broadcast status ENROUTE (via status mapping) is not directly testable easily without more mocks,
+        // but we verify the call to radio service occurred.
+    }
+
+    @Test
+    fun `sendToRadio with MeshPacket queues and sends when connected`() = runTest(testDispatcher) {
+        val packet = MeshProtos.MeshPacket.newBuilder().setId(456).build()
+        every { connectionStateHolder.connectionState } returns MutableStateFlow(ConnectionState.Connected)
+
+        handler.sendToRadio(packet)
+        testScheduler.runCurrent()
+
+        verify { radioInterfaceService.sendToRadio(any()) }
+    }
+
+    @Test
+    fun `handleQueueStatus completes deferred`() = runTest(testDispatcher) {
+        val packet = MeshProtos.MeshPacket.newBuilder().setId(789).build()
+        every { connectionStateHolder.connectionState } returns MutableStateFlow(ConnectionState.Connected)
+
+        handler.sendToRadio(packet)
+        testScheduler.runCurrent()
+
+        val status =
+            MeshProtos.QueueStatus.newBuilder()
+                .apply {
+                    meshPacketId = 789
+                    res = 0 // Success
+                    free = 1
+                }
+                .build()
+
+        handler.handleQueueStatus(status)
+        testScheduler.runCurrent()
+
+        // If it completed, the queue job should move to the next packet or finish.
+        // We can't easily check the deferred inside, but we can check if it cleared the internal wait.
+    }
+}