Write Test Code In 'core.domain' package

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

@@ -0,0 +1,112 @@
+/*
+ * 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.delay
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.test.runTest
+import org.junit.Rule
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class GetRecentSearchQueriesUseCaseTest {
+
+    @get:Rule
+    val mainDispatcherRule = MainDispatcherRule()
+
+    private val recentSearchRepository = TestRecentSearchRepository()
+
+    private val useCase = GetRecentSearchQueriesUseCase(
+        recentSearchRepository,
+    )
+
+    @Test
+    fun whenNoParams_recentSearchQueriesAreReturnedUpTo10() = runTest {
+        // Obtain a stream of recent search queries with no param.
+        val recentSearchQueries = useCase()
+
+        // insert 5 search queries.
+        for (index in 0 until 5) {
+            recentSearchRepository.insertOrReplaceRecentSearch(testRecentSearchQueries[index])
+            // delay for saving value
+            delay(10L)
+        }
+
+        // Check that 5 recent search queries are ordered by latest.
+        assertEquals(
+            testRecentSearchQueries.take(5).reversed(),
+            recentSearchQueries.first().map { it.query },
+        )
+
+        // insert 9 more search queries.
+        for (index in 5 until testRecentSearchQueries.size) {
+            recentSearchRepository.insertOrReplaceRecentSearch(testRecentSearchQueries[index])
+            // delay for saving value
+            delay(10L)
+        }
+
+        // Check that recent search queries are ordered by latest up to 10.
+        assertEquals(
+            testRecentSearchQueries.reversed().take(10),
+            recentSearchQueries.first().map { it.query },
+        )
+    }
+
+    @Test
+    fun whenParamIsSetTo5_recentSearchQueriesAreReturnedUpTo5() = runTest {
+        // Obtain a stream of recent search queries with param set 5.
+        val recentSearchQueries = useCase(5)
+
+        // insert 2 search queries.
+        for (index in 0 until 2) {
+            recentSearchRepository.insertOrReplaceRecentSearch(testRecentSearchQueries[index])
+            // delay for saving value
+            delay(10L)
+        }
+
+        // Check that 5 recent search queries are ordered by latest.
+        assertEquals(
+            testRecentSearchQueries.take(2).reversed(),
+            recentSearchQueries.first().map { it.query },
+        )
+
+        // insert 12 more search queries.
+        for (index in 2 until testRecentSearchQueries.size) {
+            recentSearchRepository.insertOrReplaceRecentSearch(testRecentSearchQueries[index])
+            // delay for saving value
+            delay(10L)
+        }
+
+        // Check that recent search queries are ordered by latest up to 5.
+        assertEquals(
+            testRecentSearchQueries.reversed().take(5),
+            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))