[WIP] Unit tests/basics

buildSrc/settings.gradle.kts

@@ -3,5 +3,8 @@ dependencyResolutionManagement {
         create("appLibs") {
             from(files("../gradle/dependencies.toml"))
         }
+        create("testLibs") {
+            from(files("../gradle/testDependencies.toml"))
+        }
     }
 }

core/src/main/java/com/tapptitude/core/usecase/LoadImageUseCase.kt

@@ -3,7 +3,7 @@ package com.tapptitude.core.usecase
 import com.tapptitude.core.model.Image
 import com.tapptitude.core.repository.ImageRepository
 
-class LoadImageUseCase internal constructor(private val imageRepository: ImageRepository) {
+class LoadImageUseCase constructor(private val imageRepository: ImageRepository) {
 
     suspend fun invoke(): Image = imageRepository.getRandomImage()
 }

featureHome/build.gradle.kts

@@ -20,4 +20,7 @@ dependencies {
     implementation(appLibs.bundles.androidXLifecycleBundle)
     implementation(appLibs.bundles.androidXNavigationBundle)
     implementation(appLibs.bundles.koinBundle)
+
+    testImplementation(testLibs.kotlinXCoroutines)
+    testImplementation(testLibs.bundles.testBundle)
 }

featureHome/src/main/java/com/tapptitude/featurehome/presentation/HomeViewModel.kt

@@ -16,7 +16,7 @@ class HomeViewModel(
     private val loadImageUseCase: LoadImageUseCase,
     private val sessionManager: SessionManager
 ) : ViewModel() {
-    private val _isLoading = MutableLiveData<Boolean>()
+    private val _isLoading = MutableLiveData<Boolean>(false)
     val isLoading: LiveData<Boolean> = _isLoading
 
     private val _imageData = MutableLiveData<Image>()

featureHome/src/test/kotlin/com/tapptitude/featurehome/HomeViewModelTest.kt

@@ -0,0 +1,51 @@
+package com.tapptitude.featurehome
+
+import com.tapptitude.core.usecase.LoadImageUseCase
+import com.tapptitude.featurehome.fake.FAKE_IMAGE
+import com.tapptitude.featurehome.fake.FakeImageRepository
+import com.tapptitude.featurehome.fake.FakeSessionManager
+import com.tapptitude.featurehome.presentation.HomeViewModel
+import com.tapptitude.session.SessionManager
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Before
+import org.junit.Test
+
+internal class HomeViewModelTest {
+
+    private val loadImageUsecase: LoadImageUseCase = LoadImageUseCase(
+        imageRepository = FakeImageRepository(requestDelay = 0, fakeImage = FAKE_IMAGE)
+    )
+    private lateinit var fakeSessionManager: SessionManager
+    private lateinit var viewModel: HomeViewModel
+
+    @Before
+    fun setup() {
+        fakeSessionManager = FakeSessionManager()
+
+        viewModel = HomeViewModel(
+            loadImageUseCase = loadImageUsecase,
+            sessionManager = fakeSessionManager,
+        )
+    }
+
+    @After
+    fun tearDown() = Unit
+
+    @Test
+    fun `initial state is not loading`() {
+        assertEquals(
+            false,
+            viewModel.isLoading.value,
+        )
+    }
+
+    @Test
+    fun `assert no image is present at start`() {
+        // We do not make any request. We shouldn't have any image
+        assertEquals(
+            null,
+            viewModel.imageData.value,
+        )
+    }
+}

featureHome/src/test/kotlin/com/tapptitude/featurehome/fake/FakeImage.kt

@@ -0,0 +1,5 @@
+package com.tapptitude.featurehome.fake
+
+import com.tapptitude.core.model.Image
+
+internal val FAKE_IMAGE = Image("test_url")

featureHome/src/test/kotlin/com/tapptitude/featurehome/fake/FakeImageRepository.kt

@@ -0,0 +1,17 @@
+package com.tapptitude.featurehome.fake
+
+import com.tapptitude.core.model.Image
+import com.tapptitude.core.repository.ImageRepository
+import kotlinx.coroutines.delay
+
+
+internal class FakeImageRepository(
+    var requestDelay: Long = 0,
+    private val fakeImage: Image = Image("test_url"),
+) : ImageRepository {
+
+    override suspend fun getRandomImage(): Image {
+        delay(requestDelay)
+        return fakeImage
+    }
+}

featureHome/src/test/kotlin/com/tapptitude/featurehome/fake/FakeSessionManager.kt

@@ -0,0 +1,30 @@
+package com.tapptitude.featurehome.fake
+
+import com.tapptitude.session.SessionManager
+import com.tapptitude.session.model.LoggedIn
+import com.tapptitude.session.model.LoggedOut
+import com.tapptitude.session.model.LoginState
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+
+internal class FakeSessionManager : SessionManager {
+    private val _currentLoginStateFlow: MutableStateFlow<LoginState> = MutableStateFlow(
+        LoggedOut("")
+    )
+
+    override val currentLoginStateFlow: StateFlow<LoginState>
+        get() = _currentLoginStateFlow
+
+    override fun onLoggedIn(accessToken: String, userId: String) {
+        _currentLoginStateFlow.value = LoggedIn(
+            sessionToken = accessToken,
+            userId = userId
+        )
+    }
+
+    override fun onLoggedOut(lastUserId: String?) {
+        _currentLoginStateFlow.value = LoggedOut(
+            null
+        )
+    }
+}

gradle/testDependencies.toml

@@ -1,8 +1,12 @@
 [versions]
 junit = "4.13.2"
+mockWebServer = "4.10.0"
+kotlinX = "1.6.4"
 
 [libraries]
 junit = { module = "junit:junit", version.ref = "junit" }
+mockWebServer = {module = "com.squareup.okhttp3:mockwebserver", version.ref = "mockWebServer" }
+kotlinXCoroutines = {module = "org.jetbrains.kotlinx:kotlinx-coroutines-test", version.ref = "kotlinX"}
 
 [bundles]
 testBundle = [

network/build.gradle.kts

@@ -15,4 +15,7 @@ dependencies {
     implementation(appLibs.kotlinXCoroutines)
     implementation(appLibs.moshi)
     ksp(appLibs.moshiKsp)
-}
+
+    testImplementation(testLibs.bundles.testBundle)
+    testImplementation(testLibs.mockWebServer)
+}

network/src/main/java/com/tapptitude/network/interceptor/SessionInterceptor.kt

@@ -1,5 +1,6 @@
 package com.tapptitude.network.interceptor
 
+import androidx.annotation.VisibleForTesting
 import com.tapptitude.session.SessionManager
 import com.tapptitude.session.model.LoggedIn
 import okhttp3.Interceptor
@@ -21,6 +22,7 @@ internal class SessionInterceptor(private val sessionManager: SessionManager) :
     }
 
     companion object {
-        private const val HEADER_AUTHORIZATION = "Authorization"
+        @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+        internal const val HEADER_AUTHORIZATION = "Authorization"
     }
 }

network/src/test/kotlin/com/tapptitude/network/SessionInterceptorTest.kt

@@ -0,0 +1,88 @@
+package com.tapptitude.network
+
+import com.tapptitude.network.fake.FakeSessionManager
+import com.tapptitude.network.fake.IgnoredCallback
+import com.tapptitude.network.interceptor.SessionInterceptor
+import com.tapptitude.session.SessionManager
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.mockwebserver.MockWebServer
+import org.junit.After
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+
+/**
+ * Underneath, Retrofit2 uses OkHttp for requests.
+ *
+ * Thus, if we want to test an interceptor, it is enough to use a OkHttp object.
+ * No need to create an instance of retrofit
+ */
+internal class SessionInterceptorTest {
+    private lateinit var interceptor: SessionInterceptor
+    private lateinit var sessionManager: SessionManager
+    private lateinit var okHttpClient: OkHttpClient
+    private lateinit var mockWebServer: MockWebServer
+
+    @Before
+    fun `before each test, do a fresh set up`() {
+        sessionManager = FakeSessionManager()
+        interceptor = SessionInterceptor(sessionManager)
+        okHttpClient = OkHttpClient.Builder()
+            .addInterceptor(interceptor)
+            .build()
+
+        mockWebServer = MockWebServer()
+        mockWebServer.start()
+    }
+
+    @After
+    fun `after each test, clean up the resource`() {
+        mockWebServer.shutdown()
+    }
+
+    @Test
+    fun `assert when logged in the authorization header is set`() {
+        val mockUserId = "mocked_user_id"
+        val mockedAccessToken = "mocked_access_token"
+
+        // we logged in the user
+        sessionManager.onLoggedIn(accessToken = mockedAccessToken, userId = mockUserId)
+
+        val request = Request.Builder()
+            .url(mockWebServer.url("test"))
+            .get()
+            .build()
+
+        okHttpClient.newCall(request).enqueue(IgnoredCallback)
+
+        val receivedRequest = mockWebServer.takeRequest()
+
+        assertTrue(
+            "The Authorization token is not present!",
+            receivedRequest.headers.contains(
+                SessionInterceptor.HEADER_AUTHORIZATION to mockedAccessToken
+            )
+        )
+    }
+
+    @Test
+    fun `assert when logged out the authorization header is NOT set`() {
+        sessionManager.onLoggedOut(null)
+
+        val request = Request.Builder()
+            .url(mockWebServer.url("test"))
+            .get()
+            .build()
+
+        okHttpClient.newCall(request).enqueue(IgnoredCallback)
+
+        val receivedRequest = mockWebServer.takeRequest()
+
+        assertFalse(
+            "The authorization token should not be set",
+            receivedRequest.headers.any { it.first == SessionInterceptor.HEADER_AUTHORIZATION }
+        )
+    }
+}

network/src/test/kotlin/com/tapptitude/network/fake/FakeSessionManager.kt

@@ -0,0 +1,30 @@
+package com.tapptitude.network.fake
+
+import com.tapptitude.session.SessionManager
+import com.tapptitude.session.model.LoggedIn
+import com.tapptitude.session.model.LoggedOut
+import com.tapptitude.session.model.LoginState
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+
+internal class FakeSessionManager : SessionManager {
+    private val _currentLoginStateFlow: MutableStateFlow<LoginState> = MutableStateFlow(
+        LoggedOut("")
+    )
+
+    override val currentLoginStateFlow: StateFlow<LoginState>
+        get() = _currentLoginStateFlow
+
+    override fun onLoggedIn(accessToken: String, userId: String) {
+        _currentLoginStateFlow.value = LoggedIn(
+            sessionToken = accessToken,
+            userId = userId
+        )
+    }
+
+    override fun onLoggedOut(lastUserId: String?) {
+        _currentLoginStateFlow.value = LoggedOut(
+            null
+        )
+    }
+}

network/src/test/kotlin/com/tapptitude/network/fake/IgnoredCallback.kt

@@ -0,0 +1,15 @@
+package com.tapptitude.network.fake
+
+import java.io.IOException
+import okhttp3.Call
+import okhttp3.Callback
+import okhttp3.Response
+
+/**
+ * An empty [Callback] to be used in testing.
+ * Does nothing.
+ */
+internal object IgnoredCallback : Callback {
+    override fun onFailure(call: Call, e: IOException) = Unit
+    override fun onResponse(call: Call, response: Response) = Unit
+}