Implemented GithubReposVMTest #2

ui-githubrepos/src/test/java/com/mutualmobile/feat/githubrepos/ui/github/repolist/GithubReposVMTest.kt

@@ -4,16 +4,17 @@ import androidx.arch.core.executor.testing.InstantTaskExecutorRule
 import androidx.paging.PagingData
 import app.cash.turbine.test
 import com.mutualmobile.feat.githubrepos.ui.model.UIRepoMapper
+import com.mutualmobile.feat.githubrepos.utils.getOrAwaitValue
 import com.mutualmobile.praxis.data.repository.GithubRepoImpl
 import com.mutualmobile.praxis.domain.model.DOMOwner
 import com.mutualmobile.praxis.domain.model.DOMRepo
 import com.mutualmobile.praxis.domain.usecases.GetGithubTrendingReposUseCase
-import com.mutualmobile.praxis.navigator.asFlow
 import io.mockk.MockKAnnotations
 import io.mockk.coEvery
 import io.mockk.impl.annotations.MockK
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.test.StandardTestDispatcher
@@ -29,7 +30,10 @@ import org.junit.rules.TestRule
 @ExperimentalCoroutinesApi
 class GithubReposVMTest {
 
-    // Important for your test's execution while testing LiveData
+    /**
+     * Important for your test's execution while testing LiveData.
+     * Fixes error message: "Android looper not mocked"
+     */
     @get:Rule
     var rule: TestRule = InstantTaskExecutorRule()
 
@@ -58,35 +62,33 @@ class GithubReposVMTest {
     @Test
     fun `test that trendingGithubRepos() completes without exception`() = runTest {
         launch {
-            val testRepo = flowOf(
-                PagingData.from(
-                    listOf(
-                        DOMRepo(
+            val testRepo = PagingData.from(
+                listOf(
+                    DOMRepo(
+                        id = 0,
+                        name = "Test",
+                        fullName = "Test",
+                        description = "Test",
+                        url = "Test",
+                        stars = 0,
+                        forks = 0,
+                        language = "Test",
+                        watchers = 0,
+                        owner = DOMOwner(
                             id = 0,
-                            name = "Test",
-                            fullName = "Test",
-                            description = "Test",
-                            url = "Test",
-                            stars = 0,
-                            forks = 0,
-                            language = "Test",
-                            watchers = 0,
-                            owner = DOMOwner(
-                                id = 0,
-                                login = "Test",
-                                avatarUrl = "Test"
-                            ),
-                            createDate = "Test",
-                            updateDate = "Test",
-                            openIssues = 0
-                        )
+                            login = "Test",
+                            avatarUrl = "Test"
+                        ),
+                        createDate = "Test",
+                        updateDate = "Test",
+                        openIssues = 0
                     )
                 )
             )
 
             coEvery {
                 githubRepoImpl.getTrendingRepos("flutter")
-            } returns testRepo
+            } returns flowOf(testRepo)
 
             githubTrendingReposUseCase = GetGithubTrendingReposUseCase(githubRepoImpl)
 
@@ -96,9 +98,11 @@ class GithubReposVMTest {
             )
 
             githubReposVM.getGitHubTrendingRepos()
+            delay(1) // Because we need our liveData to be assigned first before testing
 
-            githubReposVM.reposFlowLiveData.asFlow().test {
+            githubReposVM.reposFlowLiveData.getOrAwaitValue().test {
                 assert(awaitItem() == testRepo)
+                cancelAndConsumeRemainingEvents()
             }
         }
     }

ui-githubrepos/src/test/java/com/mutualmobile/feat/githubrepos/utils/LiveDataUtil.kt

@@ -0,0 +1,63 @@
+package com.mutualmobile.feat.githubrepos.utils
+
+/*
+ * Copyright (C) 2019 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
+ *
+ *      http://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.
+ */
+
+import androidx.annotation.VisibleForTesting
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.Observer
+import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.TimeoutException
+
+/**
+ * Gets the value of a [LiveData] or waits for it to have one, with a timeout.
+ *
+ * Use this extension from host-side (JVM) tests. It's recommended to use it alongside
+ * `InstantTaskExecutorRule` or a similar mechanism to execute tasks synchronously.
+ */
+@VisibleForTesting(otherwise = VisibleForTesting.NONE)
+fun <T> LiveData<T>.getOrAwaitValue(
+    time: Long = 2,
+    timeUnit: TimeUnit = TimeUnit.SECONDS,
+    afterObserve: () -> Unit = {}
+): T {
+    var data: T? = null
+    val latch = CountDownLatch(1)
+    val observer = object : Observer<T> {
+        override fun onChanged(o: T?) {
+            data = o
+            latch.countDown()
+            this@getOrAwaitValue.removeObserver(this)
+        }
+    }
+    this.observeForever(observer)
+
+    try {
+        afterObserve.invoke()
+
+        // Don't wait indefinitely if the LiveData is not set.
+        if (!latch.await(time, timeUnit)) {
+            throw TimeoutException("LiveData value was never set.")
+        }
+
+    } finally {
+        this.removeObserver(observer)
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    return data as T
+}