Add a basic UI test

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

app/build.gradle

@@ -75,4 +75,5 @@ dependencies {
     testImplementation 'junit:junit:4.13'
     androidTestImplementation 'androidx.test.ext:junit:1.1.1'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
+    androidTestImplementation "androidx.ui:ui-test:$compose_version"
 }

app/src/androidTest/java/dev/msfjarvis/todo/MainActivityTest.kt

@@ -0,0 +1,29 @@
+package dev.msfjarvis.todo
+
+import androidx.ui.test.android.createAndroidComposeRule
+import androidx.ui.test.assertIsDisplayed
+import androidx.ui.test.onNodeWithText
+import dev.msfjarvis.todo.ui.TodoTheme
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+
+class MainActivityTest {
+
+  @get:Rule
+  val composeTestRule = createAndroidComposeRule<MainActivity>(disableTransitions = true)
+
+  @Before
+  fun setUp() {
+    composeTestRule.setContent {
+      TodoTheme {
+        TodoApp()
+      }
+    }
+  }
+
+  @Test
+  fun test_default_item() {
+    onNodeWithText("Default item").assertIsDisplayed()
+  }
+}