Refactoring FormulaAndroid slightly and increasing code-coverage.

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

@@ -0,0 +1,37 @@
+package com.instacart.formula
+
+import android.app.Application
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class FormulaAndroidTest {
+
+    @Test fun `crashes if initialized twice`() {
+
+        try {
+            val result = runCatching {
+                val context = ApplicationProvider.getApplicationContext<Application>()
+                FormulaAndroid.init(context) {}
+                FormulaAndroid.init(context) {}
+            }
+            val error = result.exceptionOrNull()?.message
+            Truth.assertThat(error).isEqualTo("can only initialize the store once.")
+        } finally {
+            FormulaAndroid.reset()
+        }
+    }
+
+    @Test fun `crashes if accessed before initialization`() {
+        val result = runCatching {
+            FormulaAndroid.onBackPressed(ActivityUpdateTest.TestActivity())
+        }
+        val errorMessage = result.exceptionOrNull()?.message
+        Truth.assertThat(errorMessage).isEqualTo(
+            "Need to call FormulaAndroid.init() from your Application."
+        )
+    }
+}

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

@@ -11,13 +11,13 @@ import com.instacart.formula.android.FragmentEnvironment
 import com.instacart.formula.android.internal.ActivityStoreFactory
 import com.instacart.formula.android.internal.AppManager
 import com.instacart.formula.android.FragmentKey
-import com.instacart.formula.android.internal.FormulaFragmentDelegate
 import java.lang.IllegalStateException
 
 object FormulaAndroid {
 
     private var application: Application? = null
     private var appManager: AppManager? = null
+    private var fragmentEnvironment: FragmentEnvironment? = null
 
     /**
      * Initializes Formula Android integration. Should be called within [Application.onCreate].
@@ -40,39 +40,22 @@ object FormulaAndroid {
 
         this.application = application
         this.appManager = appManager
-        FormulaFragmentDelegate.appManager = appManager
-        FormulaFragmentDelegate.fragmentEnvironment = fragmentEnvironment
-    }
-
-    /**
-     * Initializes Formula Android integration. Should be called within [Application.onCreate].
-     *
-     * @param logger A logger for debug Formula Android events.
-     * @param onFragmentError A global handler for fragment errors. Override this to log the crashes.
-     */
-    fun init(
-        application: Application,
-        logger: ((String) -> Unit)? = null,
-        onFragmentError: (FragmentKey, Throwable) -> Unit = { _, it -> throw it },
-        activities: ActivityConfigurator.() -> Unit
-    ) {
-        val fragmentEnvironment = FragmentEnvironment(logger ?: {}, onFragmentError)
-        init(application, fragmentEnvironment, activities)
+        this.fragmentEnvironment = fragmentEnvironment
     }
 
     /**
      * Call this method in [FragmentActivity.onCreate] before calling [FragmentActivity.super.onCreate]
      */
     fun onPreCreate(activity: FragmentActivity, savedInstance: Bundle?) {
-        managerOrThrow(activity).onPreCreate(activity, savedInstance)
+        appManagerOrThrow().onPreCreate(activity, savedInstance)
     }
 
     /**
      * Call this method in [FragmentActivity.onActivityResult]
      */
     fun onActivityResult(activity: FragmentActivity, requestCode: Int, resultCode: Int, data: Intent?) {
         val result = ActivityResult(requestCode, resultCode, data)
-        managerOrThrow(activity).onActivityResult(activity, result)
+        appManagerOrThrow().onActivityResult(activity, result)
     }
 
     /**
@@ -91,21 +74,30 @@ object FormulaAndroid {
      * ```
      */
     fun onBackPressed(activity: FragmentActivity): Boolean {
-        return managerOrThrow(activity).onBackPressed(activity)
-    }
-
-    private fun managerOrThrow(activity: FragmentActivity): AppManager {
-        return appManager ?: throw IllegalStateException("call FormulaAndroid.init() from your Application: $activity")
+        return appManagerOrThrow().onBackPressed(activity)
     }
 
     /**
      * Used in testing to clear current store manager.
      */
     @VisibleForTesting fun reset() {
-        val app = application ?: throw IllegalStateException("not initialized")
+        val app = ensureInitialized(application)
         app.unregisterActivityLifecycleCallbacks(appManager)
 
         application = null
         appManager = null
     }
+
+
+    internal fun appManagerOrThrow(): AppManager {
+        return ensureInitialized(appManager)
+    }
+
+    internal fun fragmentEnvironment(): FragmentEnvironment {
+        return ensureInitialized(fragmentEnvironment)
+    }
+
+    private fun <T : Any> ensureInitialized(variable: T?): T {
+        return checkNotNull(variable) { "Need to call FormulaAndroid.init() from your Application." }
+    }
 }

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

@@ -5,6 +5,7 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
+import com.instacart.formula.FormulaAndroid
 import com.instacart.formula.android.internal.FormulaFragmentDelegate
 import com.instacart.formula.android.internal.getFormulaFragmentId
 import java.lang.Exception
@@ -33,7 +34,7 @@ class FormulaFragment : Fragment(), BaseFormulaFragment<Any> {
     }
 
     private val environment: FragmentEnvironment
-        get() = FormulaFragmentDelegate.fragmentEnvironment()
+        get() = FormulaAndroid.fragmentEnvironment()
 
     private val fragmentDelegate: FragmentEnvironment.FragmentDelegate
         get() = environment.fragmentDelegate

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

@@ -35,10 +35,10 @@ internal class CompositeBinding<ParentComponent, ScopedComponent>(
             val component = state.component
             if (component != null) {
                 val childInput = Input(
-                    input.environment,
-                    component.component,
-                    input.activeFragments,
-                    input.onInitializeFeature,
+                    environment = input.environment,
+                    component = component.component,
+                    activeFragments = input.activeFragments,
+                    onInitializeFeature = input.onInitializeFeature,
                 )
                 bindings.forEachIndices {
                     it.bind(context, childInput)

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

@@ -1,16 +1,13 @@
 package com.instacart.formula.android.internal
 
+import com.instacart.formula.FormulaAndroid
+import com.instacart.formula.FormulaAndroid.fragmentEnvironment
 import com.instacart.formula.android.FormulaFragment
-import com.instacart.formula.android.FragmentEnvironment
-import com.instacart.formula.android.FragmentKey
 import com.instacart.formula.android.ViewFactory
 
 internal object FormulaFragmentDelegate {
-    var appManager: AppManager? = null
-    var fragmentEnvironment: FragmentEnvironment? = null
-
     fun viewFactory(fragment: FormulaFragment): ViewFactory<Any>? {
-        val appManager = checkNotNull(appManager) { "FormulaAndroid.init() not called." }
+        val appManager = FormulaAndroid.appManagerOrThrow()
 
         val activity = fragment.activity ?: run {
             fragmentEnvironment().logger("FormulaFragment has no activity attached: ${fragment.getFragmentKey()}")
@@ -30,9 +27,4 @@ internal object FormulaFragmentDelegate {
         }
         return viewFactory
     }
-
-
-    fun fragmentEnvironment(): FragmentEnvironment {
-        return checkNotNull(fragmentEnvironment) { "FormulaAndroid.init() not called." }
-    }
 }

samples/stopwatch-compose/src/main/java/com/instacart/formula/compose/stopwatch/StopwatchApp.kt

@@ -3,6 +3,7 @@ package com.instacart.formula.compose.stopwatch
 import android.app.Application
 import android.util.Log
 import com.instacart.formula.FormulaAndroid
+import com.instacart.formula.android.FragmentEnvironment
 
 class StopwatchApp : Application() {
 
@@ -11,9 +12,11 @@ class StopwatchApp : Application() {
 
         FormulaAndroid.init(
             application = this,
-            onFragmentError = { contract, error ->
-                Log.e("StopwatchApp", "fragment crashed", error)
-            },
+            fragmentEnvironment = FragmentEnvironment(
+                onScreenError = { key, error ->
+                    Log.e("StopwatchApp", "fragment crashed", error)
+                }
+            ),
             activities = {
                 activity<StopwatchActivity> {
                     store(

samples/todoapp/src/main/java/com/examples/todoapp/TodoApp.kt

@@ -4,6 +4,7 @@ import android.app.Application
 import android.util.Log
 import com.examples.todoapp.tasks.TaskListFeatureFactory
 import com.instacart.formula.FormulaAndroid
+import com.instacart.formula.android.FragmentEnvironment
 
 class TodoApp : Application() {
 
@@ -12,9 +13,11 @@ class TodoApp : Application() {
 
         FormulaAndroid.init(
             application = this,
-            onFragmentError = { contract, error ->
-                Log.e("TodoApp", "fragment crashed", error)
-            },
+            fragmentEnvironment = FragmentEnvironment(
+                onScreenError = { _, error ->
+                    Log.e("TodoApp", "fragment crashed", error)
+                }
+            ),
             activities = {
                 activity<TodoActivity> {
                     val component = TodoAppComponent(this)