Write Test Code In 'core.domain' package

core/domain/src/test/kotlin/com/google/samples/apps/nowinandroid/core/domain/GetFollowableTopicsUseCaseTest.kt

@@ -28,6 +28,9 @@ import org.junit.Rule
 import org.junit.Test
 import kotlin.test.assertEquals
 
+/**
+ * Unit test for [GetFollowableTopicsUseCase]
+ */
 class GetFollowableTopicsUseCaseTest {
 
     @get:Rule
@@ -42,7 +45,7 @@ class GetFollowableTopicsUseCaseTest {
     )
 
     @Test
-    fun whenNoParams_followableTopicsAreReturnedWithNoSorting() = runTest {
+    fun whenSortOrderIsByNone_followableTopicsAreReturnedWithNoSorting() = runTest {
         // Obtain a stream of followable topics.
         val followableTopics = useCase()
 

core/domain/src/test/kotlin/com/google/samples/apps/nowinandroid/core/domain/GetRecentSearchQueriesUseCaseTest.kt

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2024 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.domain
+
+import com.google.samples.apps.nowinandroid.core.testing.repository.TestRecentSearchRepository
+import com.google.samples.apps.nowinandroid.core.testing.util.MainDispatcherRule
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.runTest
+import org.junit.Rule
+import org.junit.Test
+import kotlin.test.assertEquals
+
+/**
+ * Unit test for [GetRecentSearchQueriesUseCase]
+ */
+class GetRecentSearchQueriesUseCaseTest {
+
+    @get:Rule
+    val mainDispatcherRule = MainDispatcherRule()
+
+    private val recentSearchRepository = TestRecentSearchRepository()
+
+    private val useCase = GetRecentSearchQueriesUseCase(
+        recentSearchRepository,
+    )
+
+    @Test
+    fun whenQueryLimitIsBy10_recentSearchQueriesAreReturnedUpTo10() = runTest {
+        // Obtain a stream of recent search queries with no param.
+        val recentSearchQueries = useCase()
+
+        // insert search queries over 10.
+        testRecentSearchQueries.forEach { query ->
+            recentSearchRepository.insertOrReplaceRecentSearch(query)
+        }
+
+        // Check that the number of recent search queries are up to 10.
+        assertEquals(
+            10,
+            recentSearchQueries.first().size,
+        )
+    }
+
+    @Test
+    fun whenReceivingRecentSearchQueries_recentSearchQueriesAreReturnedInRecentOrder() = runTest {
+        // Obtain a stream of recent search queries with no param.
+        val recentSearchQueries = useCase()
+
+        // insert search queries over 10.
+        testRecentSearchQueries.forEach { query ->
+            recentSearchRepository.insertOrReplaceRecentSearch(query)
+            advanceUntilIdle()
+        }
+
+        // Check that search queries is ordered in recently up to 10
+        assertEquals(
+            testRecentSearchQueries.reversed().take(10),
+            recentSearchQueries.first().map { it.query },
+        )
+    }
+}
+
+private val testRecentSearchQueries = listOf(
+    "Compose", "Wear OS",
+    "Jetpack", "Headlines",
+    "Architecture", "UI",
+    "Testing", "Android Studio",
+    "Performance", "New API",
+    "Games", "Android TV",
+    "Camera", "Media",
+)

core/testing/src/main/kotlin/com/google/samples/apps/nowinandroid/core/testing/repository/TestRecentSearchRepository.kt

@@ -19,14 +19,16 @@ package com.google.samples.apps.nowinandroid.core.testing.repository
 import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
 import com.google.samples.apps.nowinandroid.core.data.repository.RecentSearchRepository
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.flow
 
 class TestRecentSearchRepository : RecentSearchRepository {
 
     private val cachedRecentSearches: MutableList<RecentSearchQuery> = mutableListOf()
 
     override fun getRecentSearchQueries(limit: Int): Flow<List<RecentSearchQuery>> =
-        flowOf(cachedRecentSearches.sortedByDescending { it.queriedDate }.take(limit))
+        flow {
+            emit(cachedRecentSearches.sortedByDescending { it.queriedDate }.take(limit))
+        }
 
     override suspend fun insertOrReplaceRecentSearch(searchQuery: String) {
         cachedRecentSearches.add(RecentSearchQuery(searchQuery))