Increase code coverage (pt4).

formula-android-tests/src/main/AndroidManifest.xml

@@ -34,5 +34,19 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <activity android:name="com.instacart.formula.NonBoundActivityTest$TestActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <activity android:name="com.instacart.formula.NonBoundFragmentActivityTest$TestActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
     </application>
 </manifest>

formula-android-tests/src/test/java/com/instacart/formula/ActivityLifecycleEventTest.kt

@@ -57,4 +57,12 @@ class ActivityLifecycleEventTest {
         val expected = listOf(INITIALIZED) + lifecycle + lifecycle
         assertThat(events).containsExactlyElementsIn(expected).inOrder()
     }
+
+    @Test fun `calling onPreCreate() twice will throw an exception`() {
+        val activity = scenario.activity()
+        val result = runCatching { FormulaAndroid.onPreCreate(activity, null) }
+        assertThat(result.exceptionOrNull()).hasMessageThat().contains(
+            "Activity TestActivity was already initialized. Did you call FormulaAndroid.onPreCreate() twice?"
+        )
+    }
 }

formula-android-tests/src/test/java/com/instacart/formula/FormulaFragmentTest.kt

@@ -15,6 +15,7 @@ import com.instacart.formula.android.BackCallback
 import com.instacart.formula.android.FormulaFragment
 import com.instacart.formula.android.FragmentEnvironment
 import com.instacart.formula.android.FragmentStore
+import com.instacart.formula.android.events.FragmentLifecycleEvent
 import com.instacart.formula.test.TestBackCallbackRenderModel
 import com.instacart.formula.test.TestKey
 import com.instacart.formula.test.TestKeyWithId
@@ -43,6 +44,7 @@ class FormulaFragmentTest {
     private var onPreCreated: (TestFragmentActivity) -> Unit = {}
     private var updateThreads = linkedSetOf<Thread>()
     private val errors = mutableListOf<Throwable>()
+    private val fragmentLifecycleEvents = mutableListOf<FragmentLifecycleEvent>()
     private val formulaRule = TestFormulaRule(
         initFormula = { app ->
             val environment = FragmentEnvironment(
@@ -74,6 +76,9 @@ class FormulaFragmentTest {
                                     stateChanges(it)
                                 }
                             ))
+                        },
+                        onFragmentLifecycleEvent = {
+                            fragmentLifecycleEvents.add(it)
                         }
                     )
                 }
@@ -83,6 +88,7 @@ class FormulaFragmentTest {
         cleanUp = {
             lastState = null
             updateThreads = linkedSetOf()
+            fragmentLifecycleEvents.clear()
         }
     )
 
@@ -104,6 +110,11 @@ class FormulaFragmentTest {
         navigateBack()
 
         assertThat(activeContracts()).containsExactly(TestKey()).inOrder()
+
+        assertThat(fragmentLifecycleEvents).hasSize(3)
+        assertThat(fragmentLifecycleEvents[0]).isInstanceOf(FragmentLifecycleEvent.Added::class.java)
+        assertThat(fragmentLifecycleEvents[1]).isInstanceOf(FragmentLifecycleEvent.Added::class.java)
+        assertThat(fragmentLifecycleEvents[2]).isInstanceOf(FragmentLifecycleEvent.Removed::class.java)
     }
 
     @Test fun `navigating forward should have both keys in backstack`() {

formula-android-tests/src/test/java/com/instacart/formula/FragmentLifecycleTest.kt

@@ -53,7 +53,7 @@ class FragmentLifecycleTest {
                             }
                         }
                         bind(featureFactory)
-                    }
+                    },
                 )
             }
         }

formula-android-tests/src/test/java/com/instacart/formula/NonBoundActivityTest.kt

@@ -0,0 +1,43 @@
+package com.instacart.formula
+
+import android.app.Activity
+import androidx.fragment.app.FragmentActivity
+import androidx.test.core.app.ActivityScenario
+import androidx.test.ext.junit.rules.ActivityScenarioRule
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.RuleChain
+import org.junit.runner.RunWith
+
+/**
+ * Tests that formula-android module handles non-bound activities gracefully.
+ */
+@RunWith(AndroidJUnit4::class)
+class NonBoundActivityTest {
+    class TestActivity : Activity()
+
+    private val formulaRule = TestFormulaRule(
+        initFormula = { app ->
+            FormulaAndroid.init(app) {}
+        }
+    )
+
+    private val activityRule = ActivityScenarioRule(TestActivity::class.java)
+
+    @get:Rule
+    val rule = RuleChain.outerRule(formulaRule).around(activityRule)
+    lateinit var scenario: ActivityScenario<TestActivity>
+
+    @Before
+    fun setup() {
+        scenario = activityRule.scenario
+    }
+
+    @Test
+    fun `full lifecycle`() {
+        scenario.recreate()
+        scenario.close()
+    }
+}

formula-android-tests/src/test/java/com/instacart/formula/NonBoundFragmentActivityTest.kt

@@ -0,0 +1,42 @@
+package com.instacart.formula
+
+import androidx.fragment.app.FragmentActivity
+import androidx.test.core.app.ActivityScenario
+import androidx.test.ext.junit.rules.ActivityScenarioRule
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.RuleChain
+import org.junit.runner.RunWith
+
+/**
+ * Tests that formula-android module handles non-bound activities gracefully.
+ */
+@RunWith(AndroidJUnit4::class)
+class NonBoundFragmentActivityTest {
+    class TestActivity : FragmentActivity()
+
+    private val formulaRule = TestFormulaRule(
+        initFormula = { app ->
+            FormulaAndroid.init(app) {}
+        }
+    )
+
+    private val activityRule = ActivityScenarioRule(TestActivity::class.java)
+
+    @get:Rule
+    val rule = RuleChain.outerRule(formulaRule).around(activityRule)
+    lateinit var scenario: ActivityScenario<TestActivity>
+
+    @Before
+    fun setup() {
+        scenario = activityRule.scenario
+    }
+
+    @Test
+    fun `full lifecycle`() {
+        scenario.recreate()
+        scenario.close()
+    }
+}

formula-android/src/main/java/com/instacart/formula/android/ActivityConfigurator.kt

@@ -8,7 +8,7 @@ import kotlin.reflect.KClass
  */
 class ActivityConfigurator {
     internal class Binding<A : FragmentActivity>(
-        val init: ActivityStoreContext<A>.() -> ActivityStore<A>?
+        val init: ActivityStoreContext<A>.() -> ActivityStore<A>
     )
 
     internal val bindings = mutableMapOf<KClass<*>, Binding<*>>()

formula-android/src/main/java/com/instacart/formula/android/events/FragmentLifecycleEvent.kt

@@ -6,7 +6,7 @@ import com.instacart.formula.android.FragmentId
  * Models when a fragment key is attached and detached. Provides a way to indicate
  * when to initialize state stream and when to destroy it.
  */
-sealed class FragmentLifecycleEvent() {
+sealed class FragmentLifecycleEvent {
 
     abstract val fragmentId: FragmentId
 

formula-android/src/main/java/com/instacart/formula/android/internal/ActivityStoreFactory.kt

@@ -24,7 +24,7 @@ internal class ActivityStoreFactory internal constructor(
             ?: return null
 
         val activityDelegate = ActivityStoreContextImpl<A>()
-        return initializer.init.invoke(activityDelegate)?.let { store ->
+        return initializer.init.invoke(activityDelegate).let { store ->
             ActivityManager(
                 environment = environment,
                 delegate = activityDelegate,

formula-android/src/main/java/com/instacart/formula/android/internal/AppManager.kt

@@ -99,7 +99,12 @@ internal class AppManager(
     private fun <A : FragmentActivity> findOrInitActivityStore(
         activity: FragmentActivity, savedState: Bundle?
     ): ActivityManager<A> {
-        val key = findOrGenerateActivityKey(activity, savedState) // generate new key
+        if (activityToKeyMap.containsKey(activity)) {
+            throw IllegalStateException("Activity ${activity::class.java.simpleName} was already initialized. Did you call FormulaAndroid.onPreCreate() twice?")
+        }
+
+        val key =  savedState?.getString(BUNDLE_KEY) // Activity recreated, let's use saved key
+            ?: UUID.randomUUID().toString() // New activity, create new key
         activityToKeyMap[activity] = key
 
         val cached = componentMap[key] as? ActivityManager<A>?
@@ -121,13 +126,4 @@ internal class AppManager(
         val component = componentMap.remove(key)
         component?.dispose()
     }
-
-    /**
-     * Key is persisted across configuration changes.
-     */
-    private fun findOrGenerateActivityKey(activity: Activity, savedState: Bundle?): String {
-        return (activityToKeyMap[activity] // Try the map
-            ?: savedState?.getString(BUNDLE_KEY) // Try the bundle
-            ?: UUID.randomUUID().toString())
-    }
 }

formula-android/src/main/java/com/instacart/formula/android/internal/FormulaFragmentViewFactory.kt

@@ -2,6 +2,7 @@ package com.instacart.formula.android.internal
 
 import android.view.LayoutInflater
 import android.view.ViewGroup
+import androidx.annotation.VisibleForTesting
 import com.instacart.formula.android.FeatureView
 import com.instacart.formula.android.ViewFactory
 import com.instacart.formula.android.FeatureEvent
@@ -18,9 +19,22 @@ internal class FormulaFragmentViewFactory(
     private var factory: ViewFactory<Any>? = null
 
     override fun create(inflater: LayoutInflater, container: ViewGroup?): FeatureView<Any> {
+        val viewFactory = viewFactory()
+        val delegate = environment.fragmentDelegate
+        return delegate.createView(fragmentId, viewFactory, inflater, container)
+    }
+
+    @VisibleForTesting
+    internal fun viewFactory(): ViewFactory<Any> {
+        return factory ?: findViewFactory().apply {
+            factory = this
+        }
+    }
+
+    private fun findViewFactory(): ViewFactory<Any> {
         val key = fragmentId.key
         val featureEvent = featureProvider.getFeature(fragmentId) ?: throw IllegalStateException("Could not find feature for $key.")
-        val viewFactory = factory ?: when (featureEvent) {
+        return when (featureEvent) {
             is FeatureEvent.MissingBinding -> {
                 throw IllegalStateException("Missing feature factory or integration for $key. Please check your FragmentStore configuration.")
             }
@@ -31,8 +45,5 @@ internal class FormulaFragmentViewFactory(
                 featureEvent.feature.viewFactory
             }
         }
-        this.factory = viewFactory
-        val delegate = environment.fragmentDelegate
-        return delegate.createView(fragmentId, viewFactory, inflater, container)
     }
 }

formula-android/src/main/java/com/instacart/formula/android/internal/FragmentFlowRenderView.kt

@@ -35,11 +35,12 @@ internal class FragmentFlowRenderView(
 ) {
 
     private var fragmentState: FragmentState? = null
+    private var features: Map<FragmentId, FeatureEvent> = emptyMap()
     private val visibleFragments: LinkedList<Fragment> = LinkedList()
 
     private val featureProvider = object : FeatureProvider {
         override fun getFeature(id: FragmentId): FeatureEvent? {
-            return fragmentState?.features?.get(id)
+            return features[id]
         }
     }
 
@@ -53,10 +54,7 @@ internal class FragmentFlowRenderView(
             super.onFragmentViewCreated(fm, f, v, savedInstanceState)
 
             visibleFragments.add(f)
-
-            fragmentState?.let {
-                updateVisibleFragments(it)
-            }
+            updateVisibleFragments()
 
             onFragmentViewStateChanged(f.getFormulaFragmentId(), true)
             notifyLifecycleStateChanged(f, Lifecycle.State.CREATED)
@@ -93,7 +91,10 @@ internal class FragmentFlowRenderView(
         override fun onFragmentAttached(fm: FragmentManager, f: Fragment, context: Context) {
             super.onFragmentAttached(fm, f, context)
             if (FragmentLifecycle.shouldTrack(f)) {
-                onLifecycleEvent(FragmentLifecycle.createAddedEvent(f))
+                val event = FragmentLifecycleEvent.Added(
+                    fragmentId = f.getFormulaFragmentId(),
+                )
+                onLifecycleEvent(event)
             } else {
                 fragmentEnvironment.logger("Ignoring attach event for fragment: $f")
             }
@@ -103,8 +104,12 @@ internal class FragmentFlowRenderView(
             super.onFragmentDetached(fm, f)
 
             // Only trigger detach, when fragment is actually being removed from the backstack
-            if (FragmentLifecycle.shouldTrack(f) && !FragmentLifecycle.isKept(fm, f)) {
-                val event = FragmentLifecycle.createRemovedEvent(f)
+            if (FragmentLifecycle.shouldTrack(f) && f.isRemoving) {
+                val formulaFragment = f as? BaseFormulaFragment<*>
+                val event = FragmentLifecycleEvent.Removed(
+                    fragmentId = f.getFormulaFragmentId(),
+                    lastState = formulaFragment?.currentState(),
+                )
                 onLifecycleEvent(event)
             }
         }
@@ -118,7 +123,8 @@ internal class FragmentFlowRenderView(
         Utils.assertMainThread()
 
         fragmentState = state
-        updateVisibleFragments(state)
+        features = state.features
+        updateVisibleFragments()
     }
 
     fun onBackPressed(): Boolean {
@@ -149,7 +155,8 @@ internal class FragmentFlowRenderView(
         onLifecycleState.invoke(fragment.getFormulaFragmentId(), newState)
     }
 
-    private fun updateVisibleFragments(state: FragmentState) {
+    private fun updateVisibleFragments() {
+        val state = fragmentState ?: return
         visibleFragments.forEachIndices { fragment ->
             if (fragment is BaseFormulaFragment<*>) {
                 state.outputs[fragment.getFormulaFragmentId()]?.let {

formula-android/src/main/java/com/instacart/formula/android/internal/FragmentLifecycle.kt

@@ -3,12 +3,10 @@ package com.instacart.formula.android.internal
 import android.os.Bundle
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentInspector
-import androidx.fragment.app.FragmentManager
 import com.instacart.formula.android.FragmentId
 import com.instacart.formula.android.FragmentKey
 import com.instacart.formula.android.BaseFormulaFragment
 import com.instacart.formula.android.FormulaFragment
-import com.instacart.formula.android.events.FragmentLifecycleEvent
 import java.util.UUID
 
 /**
@@ -19,19 +17,6 @@ internal object FragmentLifecycle {
     internal fun shouldTrack(fragment: Fragment): Boolean {
         return !fragment.retainInstance && !FragmentInspector.isHeadless(fragment)
     }
-
-    internal fun isKept(fragmentManager: FragmentManager, fragment: Fragment): Boolean {
-        return !fragment.isRemoving
-    }
-
-    internal fun createAddedEvent(f: Fragment): FragmentLifecycleEvent.Added {
-        return FragmentLifecycleEvent.Added(f.getFormulaFragmentId())
-    }
-
-    internal fun createRemovedEvent(f: Fragment): FragmentLifecycleEvent.Removed {
-        val fragment = f as? BaseFormulaFragment<*>
-        return FragmentLifecycleEvent.Removed(f.getFormulaFragmentId(), fragment?.currentState())
-    }
 }
 
 private fun Fragment.getFragmentKey(): FragmentKey {
@@ -47,12 +32,10 @@ private fun Fragment.getFragmentInstanceId(): String {
     return if (this is BaseFormulaFragment<*>) {
         val arguments = getOrSetArguments()
         val id = arguments.getString(FormulaFragment.ARG_FORMULA_ID, "")
-        if (id.isNullOrBlank()) {
+        id.ifBlank {
             val initializedId = UUID.randomUUID().toString()
             arguments.putString(FormulaFragment.ARG_FORMULA_ID, initializedId)
             initializedId
-        } else {
-            id
         }
     } else {
         ""