Added Test and Fake ErrorMonitors, updated tests

Fake Error Monitor as EmptyErrorMonitor, containing no messages

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -109,7 +109,7 @@ fun NiaApp(
             LaunchedEffect(stateMessage) {
                 stateMessage?.let { message ->
 
-                    //Text and Duration values dictated by the UI
+                    // Text and Duration values dictated by the UI
                     val (text, duration) = getSnackbarValues(context, message)
 
                     // Determine whether user clicked action button
@@ -301,4 +301,4 @@ private fun getSnackbarValues(context: Context, message: MessageData): Pair<Stri
         is MESSAGE -> (message.type as MESSAGE).value to SnackbarDuration.Long
         UNKNOWN -> context.getString(R.string.unknown_error) to SnackbarDuration.Short
     }
-}
+}

app/src/testDemo/kotlin/com/google/samples/apps/nowinandroid/ui/NiaAppScreenSizesScreenshotTests.kt

@@ -32,6 +32,7 @@ import com.github.takahirom.roborazzi.captureRoboImage
 import com.google.samples.apps.nowinandroid.core.data.repository.TopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserNewsResourceRepository
+import com.google.samples.apps.nowinandroid.core.data.util.ErrorMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.NetworkMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.TimeZoneMonitor
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.NiaTheme
@@ -80,6 +81,9 @@ class NiaAppScreenSizesScreenshotTests {
     @Inject
     lateinit var networkMonitor: NetworkMonitor
 
+    @Inject
+    lateinit var errorMonitor: ErrorMonitor
+
     @Inject
     lateinit var timeZoneMonitor: TimeZoneMonitor
 
@@ -123,6 +127,7 @@ class NiaAppScreenSizesScreenshotTests {
                     NiaTheme {
                         val fakeAppState = rememberNiaAppState(
                             networkMonitor = networkMonitor,
+                            errorMonitor = errorMonitor,
                             userNewsResourceRepository = userNewsResourceRepository,
                             timeZoneMonitor = timeZoneMonitor,
                         )

app/src/testDemo/kotlin/com/google/samples/apps/nowinandroid/ui/NiaAppStateTest.kt

@@ -27,8 +27,10 @@ import androidx.navigation.compose.composable
 import androidx.navigation.createGraph
 import androidx.navigation.testing.TestNavHostController
 import com.google.samples.apps.nowinandroid.core.data.repository.CompositeUserNewsResourceRepository
+import com.google.samples.apps.nowinandroid.core.data.util.ErrorMonitor
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestNewsRepository
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestUserDataRepository
+import com.google.samples.apps.nowinandroid.core.testing.util.TestErrorMonitor
 import com.google.samples.apps.nowinandroid.core.testing.util.TestNetworkMonitor
 import com.google.samples.apps.nowinandroid.core.testing.util.TestTimeZoneMonitor
 import dagger.hilt.android.testing.HiltAndroidTest
@@ -43,6 +45,7 @@ import org.junit.Test
 import org.junit.runner.RunWith
 import org.robolectric.RobolectricTestRunner
 import org.robolectric.annotation.Config
+import javax.inject.Inject
 import kotlin.test.assertEquals
 import kotlin.test.assertTrue
 
@@ -60,6 +63,8 @@ class NiaAppStateTest {
     // Create the test dependencies.
     private val networkMonitor = TestNetworkMonitor()
 
+    private var errorMonitor = TestErrorMonitor()
+
     private val timeZoneMonitor = TestTimeZoneMonitor()
 
     private val userNewsResourceRepository =
@@ -79,6 +84,7 @@ class NiaAppStateTest {
                     navController = navController,
                     coroutineScope = backgroundScope,
                     networkMonitor = networkMonitor,
+                    errorMonitor = errorMonitor,
                     userNewsResourceRepository = userNewsResourceRepository,
                     timeZoneMonitor = timeZoneMonitor,
                 )
@@ -101,6 +107,7 @@ class NiaAppStateTest {
         composeTestRule.setContent {
             state = rememberNiaAppState(
                 networkMonitor = networkMonitor,
+                errorMonitor = errorMonitor,
                 userNewsResourceRepository = userNewsResourceRepository,
                 timeZoneMonitor = timeZoneMonitor,
             )
@@ -119,6 +126,7 @@ class NiaAppStateTest {
                 navController = NavHostController(LocalContext.current),
                 coroutineScope = backgroundScope,
                 networkMonitor = networkMonitor,
+                errorMonitor = errorMonitor,
                 userNewsResourceRepository = userNewsResourceRepository,
                 timeZoneMonitor = timeZoneMonitor,
             )
@@ -139,6 +147,7 @@ class NiaAppStateTest {
                 navController = NavHostController(LocalContext.current),
                 coroutineScope = backgroundScope,
                 networkMonitor = networkMonitor,
+                errorMonitor = errorMonitor,
                 userNewsResourceRepository = userNewsResourceRepository,
                 timeZoneMonitor = timeZoneMonitor,
             )

app/src/testDemo/kotlin/com/google/samples/apps/nowinandroid/ui/SnackbarInsetsScreenshotTests.kt

@@ -63,6 +63,7 @@ import com.github.takahirom.roborazzi.captureRoboImage
 import com.google.samples.apps.nowinandroid.core.data.repository.TopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserNewsResourceRepository
 import com.google.samples.apps.nowinandroid.core.data.test.repository.FakeUserDataRepository
+import com.google.samples.apps.nowinandroid.core.data.util.ErrorMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.NetworkMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.TimeZoneMonitor
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.NiaTheme
@@ -113,6 +114,9 @@ class SnackbarInsetsScreenshotTests {
     @Inject
     lateinit var networkMonitor: NetworkMonitor
 
+    @Inject
+    lateinit var errorMonitor: ErrorMonitor
+
     @Inject
     lateinit var timeZoneMonitor: TimeZoneMonitor
 
@@ -254,6 +258,7 @@ class SnackbarInsetsScreenshotTests {
                             NiaTheme {
                                 val appState = rememberNiaAppState(
                                     networkMonitor = networkMonitor,
+                                    errorMonitor = errorMonitor,
                                     userNewsResourceRepository = userNewsResourceRepository,
                                     timeZoneMonitor = timeZoneMonitor,
                                 )

app/src/testDemo/kotlin/com/google/samples/apps/nowinandroid/ui/SnackbarScreenshotTests.kt

@@ -36,6 +36,7 @@ import com.github.takahirom.roborazzi.captureRoboImage
 import com.google.samples.apps.nowinandroid.core.data.repository.TopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserNewsResourceRepository
 import com.google.samples.apps.nowinandroid.core.data.test.repository.FakeUserDataRepository
+import com.google.samples.apps.nowinandroid.core.data.util.ErrorMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.NetworkMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.TimeZoneMonitor
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.NiaTheme
@@ -86,6 +87,9 @@ class SnackbarScreenshotTests {
     @Inject
     lateinit var networkMonitor: NetworkMonitor
 
+    @Inject
+    lateinit var errorMonitor: ErrorMonitor
+
     @Inject
     lateinit var timeZoneMonitor: TimeZoneMonitor
 
@@ -203,6 +207,7 @@ class SnackbarScreenshotTests {
                         NiaTheme {
                             val appState = rememberNiaAppState(
                                 networkMonitor = networkMonitor,
+                                errorMonitor = errorMonitor,
                                 userNewsResourceRepository = userNewsResourceRepository,
                                 timeZoneMonitor = timeZoneMonitor,
                             )

core/data-test/src/main/kotlin/com/google/samples/apps/nowinandroid/core/data/test/EmptyErrorMonitor.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.data.test
+
+import com.google.samples.apps.nowinandroid.core.data.util.ErrorMonitor
+import com.google.samples.apps.nowinandroid.core.model.data.MessageData
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flowOf
+import javax.inject.Inject
+
+class EmptyErrorMonitor @Inject constructor(): ErrorMonitor {
+
+    override fun addMessageByString(message: String): MessageData {
+        TODO("Not yet implemented")
+    }
+
+    override fun addMessageByData(message: MessageData) {
+        TODO("Not yet implemented")
+    }
+
+    override fun clearMessage(message: MessageData) {
+        TODO("Not yet implemented")
+    }
+
+    override fun clearAllMessages() {
+        TODO("Not yet implemented")
+    }
+
+    override val messages: Flow<List<MessageData?>>
+        get() = flowOf(emptyList())
+
+}

core/data-test/src/main/kotlin/com/google/samples/apps/nowinandroid/core/data/test/TestDataModule.kt

@@ -27,6 +27,7 @@ import com.google.samples.apps.nowinandroid.core.data.test.repository.FakeRecent
 import com.google.samples.apps.nowinandroid.core.data.test.repository.FakeSearchContentsRepository
 import com.google.samples.apps.nowinandroid.core.data.test.repository.FakeTopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.test.repository.FakeUserDataRepository
+import com.google.samples.apps.nowinandroid.core.data.util.ErrorMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.NetworkMonitor
 import com.google.samples.apps.nowinandroid.core.data.util.TimeZoneMonitor
 import dagger.Binds
@@ -70,6 +71,11 @@ internal interface TestDataModule {
         networkMonitor: AlwaysOnlineNetworkMonitor,
     ): NetworkMonitor
 
+    @Binds
+    fun bindsErrorMonitor(
+        errorMonitor: EmptyErrorMonitor,
+    ): ErrorMonitor
+
     @Binds
     fun binds(impl: DefaultZoneIdTimeZoneMonitor): TimeZoneMonitor
 }

core/testing/src/main/kotlin/com/google/samples/apps/nowinandroid/core/testing/util/TestErrorMonitor.kt

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.testing.util
+
+import com.google.samples.apps.nowinandroid.core.data.util.ErrorMonitor
+import com.google.samples.apps.nowinandroid.core.model.data.MessageData
+import com.google.samples.apps.nowinandroid.core.model.data.MessageType
+import com.google.samples.apps.nowinandroid.core.model.data.MessageType.MESSAGE
+import com.google.samples.apps.nowinandroid.core.model.data.MessageType.OFFLINE
+import com.google.samples.apps.nowinandroid.core.model.data.MessageType.UNKNOWN
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.flowOf
+
+class TestErrorMonitor : ErrorMonitor {
+
+    private val _messages = MutableStateFlow<List<MessageData>>(emptyList())
+
+    override fun addMessageByString(message: String): MessageData {
+        TODO("Not yet implemented")
+    }
+
+    override fun addMessageByData(message: MessageData) {
+        TODO("Not yet implemented")
+    }
+
+    override fun clearMessage(message: MessageData) {
+        TODO("Not yet implemented")
+    }
+
+    override fun clearAllMessages() {
+        _messages.value = emptyList()
+    }
+
+    override val messages: Flow<List<MessageData?>>
+        get() = _messages
+
+    /**
+     * Test-only API to add message types
+     */
+
+    fun setOfflineMessage(){
+        _messages.value = listOf(OFFLINE_MESSAGE)
+    }
+
+    fun addMessage(){
+        _messages.value.plus(MESSAGE_MESSAGE)
+    }
+
+    fun addUnknownMessage(){
+        _messages.value.plus(UNKNOWN_MESSAGE)
+    }
+
+    companion object{
+        val OFFLINE_MESSAGE = MessageData(OFFLINE)
+        val MESSAGE_MESSAGE = MessageData(MESSAGE("Message"), "Title", {}, {})
+        val UNKNOWN_MESSAGE = MessageData(UNKNOWN)
+    }
+}