Add test for flow use case 4

Author: LukasLechnerDev

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/flow/usecase4/FlowUseCase4ViewModel.kt

@@ -9,7 +9,7 @@ class FlowUseCase4ViewModel(
     stockPriceDataSource: StockPriceDataSource
 ) : BaseViewModel<UiState>() {
 
-    val currentStockPriceAsFlow: Flow<UiState> = stockPriceDataSource
+    val currentStockPriceAsFlow: StateFlow<UiState> = stockPriceDataSource
         .latestStockList
         .map { stockList ->
             UiState.Success(stockList) as UiState

app/src/test/java/com/lukaslechner/coroutineusecasesonandroid/usecases/flow/usecase4/FakeStockPriceDataSource.kt

@@ -0,0 +1,18 @@
+package com.lukaslechner.coroutineusecasesonandroid.usecases.flow.usecase4
+
+import com.lukaslechner.coroutineusecasesonandroid.usecases.flow.mock.Stock
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.asSharedFlow
+
+class FakeStockPriceDataSource : StockPriceDataSource {
+
+    private val sharedFlow = MutableSharedFlow<List<Stock>>()
+
+    suspend fun emit(stockList: List<Stock>) {
+        sharedFlow.emit(stockList)
+    }
+
+    override val latestStockList: Flow<List<Stock>> = sharedFlow.asSharedFlow()
+
+}

app/src/test/java/com/lukaslechner/coroutineusecasesonandroid/usecases/flow/usecase4/FlowUseCase4ViewModelTest.kt

@@ -0,0 +1,67 @@
+package com.lukaslechner.coroutineusecasesonandroid.usecases.flow.usecase4
+
+import com.lukaslechner.coroutineusecasesonandroid.usecases.flow.usecase1.appleStock
+import com.lukaslechner.coroutineusecasesonandroid.usecases.flow.usecase1.googleStock
+import com.lukaslechner.coroutineusecasesonandroid.utils.ReplaceMainDispatcherRule
+import junit.framework.Assert.assertEquals
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.runTest
+import org.junit.Rule
+import org.junit.Test
+
+class FlowUseCase4ViewModelTest {
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    @get: Rule
+    val replaceMainDispatcherRule = ReplaceMainDispatcherRule()
+
+    @Test
+    fun `should collect loading and success ui states on successful emissions`() = runTest {
+
+        val fakeStockPriceDataSource = FakeStockPriceDataSource()
+        val viewModel = FlowUseCase4ViewModel(fakeStockPriceDataSource)
+
+        val collectJob =
+            launch(UnconfinedTestDispatcher()) {
+                viewModel.currentStockPriceAsFlow.collect()
+            }
+
+        assertEquals(
+            UiState.Loading,
+            viewModel.currentStockPriceAsFlow.value
+        )
+
+        fakeStockPriceDataSource.emit(
+            listOf(
+                googleStock,
+                appleStock
+            )
+        )
+
+        assertEquals(
+            UiState.Success(
+                listOf(
+                    googleStock,
+                    appleStock
+                )
+            ),
+            viewModel.currentStockPriceAsFlow.value
+        )
+
+        fakeStockPriceDataSource.emit(listOf(googleStock))
+
+        assertEquals(
+            UiState.Success(
+                listOf(
+                    googleStock
+                )
+            ),
+            viewModel.currentStockPriceAsFlow.value
+        )
+
+        collectJob.cancel()
+    }
+}