Add LoginViewModelTest

app/build.gradle.kts

@@ -51,6 +51,7 @@ dependencies {
     implementation(libs.androidx.compose.material3)
     implementation(libs.androidx.compose.foundation.layout)
     testImplementation(libs.junit)
+    testImplementation(libs.robolectric)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.espresso.core)
     androidTestImplementation(platform(libs.androidx.compose.bom))

app/src/main/java/com/example/mvvm/ui/login/ui/loginScreen.kt

@@ -60,7 +60,6 @@ fun Login(
     val password by viewModel.password.collectAsStateWithLifecycle()
     val enabled by viewModel.enabled.collectAsStateWithLifecycle()
     val loading by viewModel.loading.collectAsStateWithLifecycle()
-    val coroutine = rememberCoroutineScope()
 
     if (loading) {
         Box(Modifier.fillMaxSize()) {
@@ -78,11 +77,8 @@ fun Login(
             Spacer(modifier = Modifier.padding((8.dp)))
             ForgotPassword(Modifier.align(Alignment.End)) // column organiza a lo que hay debajo, la propiedad align() de los hijos de una Column espera un Alignment.Horizontal, no un Alignment completo (que es bidimensional).
             Spacer(modifier = Modifier.padding((16.dp)))
-            LoginButton(enabled ) {
-                coroutine.launch {
-                    viewModel.pressButton()
-
-                }
+            LoginButton(enabled) {
+                viewModel.pressButton()
             }
         }
 

app/src/main/java/com/example/mvvm/ui/login/ui/loginViewModel.kt

@@ -1,11 +1,14 @@
 package com.example.mvvm.ui.login.ui
 
 import android.util.Patterns
+import androidx.annotation.VisibleForTesting
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.launch
 
 class LoginViewModel : ViewModel() {
     private val _email = MutableStateFlow("") // crea un flujo mutable
@@ -29,15 +32,14 @@ class LoginViewModel : ViewModel() {
 
     }
 
+    @VisibleForTesting fun isValidEmail(email: String): Boolean = Patterns.EMAIL_ADDRESS.matcher(email).matches()
+    @VisibleForTesting fun isValidPassword(password: String): Boolean = password.length > 6
 
-    fun isValidEmail(email: String): Boolean = Patterns.EMAIL_ADDRESS.matcher(email).matches()
-    fun isValidPassword(password: String): Boolean = password.length > 6
-
-    suspend fun pressButton() {
-        _loading.value = true
-        delay(4000)
-        _loading.value = false
+    fun pressButton() {
+        viewModelScope.launch {
+            _loading.value = true
+            delay(4000)
+            _loading.value = false
+        }
     }
-
-
 }

app/src/test/java/com/example/mvvm/ui/login/ui/LoginViewModelTest.kt

@@ -0,0 +1,67 @@
+package com.example.mvvm.ui.login.ui
+
+import org.junit.Before
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+@RunWith(RobolectricTestRunner::class)
+class LoginViewModelTest {
+    private lateinit var viewModel: LoginViewModel
+
+    @Before
+    fun setup() {
+        viewModel = LoginViewModel()
+    }
+
+    @Test
+    fun `email and password are empty on launch`() {
+        assert(viewModel.email.value.isEmpty())
+        assert(viewModel.password.value.isEmpty())
+    }
+
+    @Test
+    fun `login button is not enabled on launch`() {
+        assert(!viewModel.enabled.value)
+    }
+
+    @Test
+    fun `the password value updates when the event is received`() {
+        val newPassword = "myValidPassword"
+        viewModel.onLoginChanged(
+            newEmail = "", // notice this is awkward to test when coupled
+            newPassword = newPassword,
+        )
+        assertEquals(newPassword, viewModel.password.value)
+    }
+
+    @Test
+    fun `a non-valid e-mail is not considered valid`() {
+        val emailIsValidExpected = false
+        val emailIsValidActual = viewModel.isValidEmail("bloop")
+
+        assertEquals(emailIsValidExpected, emailIsValidActual)
+    }
+
+    @Test
+    fun `a valid e-mail is considered valid`() {
+        val emailIsValidExpected = true
+        val emailIsValidActual = viewModel.isValidEmail("bloop@gmail.com")
+
+        assertEquals(emailIsValidExpected, emailIsValidActual)
+    }
+
+    @Test
+    fun `when an email and password are entered, the button to submit is enabled`() {
+        val newEmail = "myValidEmail@gmail.com"
+        val newPassword = "myValidPassword"
+
+        viewModel.onLoginChanged(
+            newEmail = newEmail,
+            newPassword = newPassword,
+        )
+
+        assert(viewModel.enabled.value)
+    }
+}

gradle/libs.versions.toml

@@ -9,6 +9,7 @@ lifecycleRuntimeKtx = "2.6.1"
 activityCompose = "1.8.0"
 composeBom = "2024.09.00"
 foundationLayout = "1.9.4"
+robolectric = "4.16"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
@@ -26,6 +27,7 @@ androidx-compose-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-
 androidx-compose-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
 androidx-compose-material3 = { group = "androidx.compose.material3", name = "material3" }
 androidx-compose-foundation-layout = { group = "androidx.compose.foundation", name = "foundation-layout", version.ref = "foundationLayout" }
+robolectric = { group = "org.robolectric", name = "robolectric", version.ref = "robolectric" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }