From 1b03419998b1b97b441eb126f8cb6f391c663f4a Mon Sep 17 00:00:00 2001
From: Laimonas Turauskas <laimiux@gmail.com>
Date: Wed, 28 Aug 2024 17:54:01 +0300
Subject: [PATCH] Update FlowAction API. (#373)

* Update FlowAction API.

* Fix test issues.
---
 .../formula/coroutines/FlowAction.kt          | 62 +++++++++----------
 .../formula/test/CoroutineTestableRuntime.kt  | 43 ++++++-------
 2 files changed, 50 insertions(+), 55 deletions(-)

diff --git a/formula-coroutines/src/main/java/com/instacart/formula/coroutines/FlowAction.kt b/formula-coroutines/src/main/java/com/instacart/formula/coroutines/FlowAction.kt
index a19315ea..9888386e 100644
--- a/formula-coroutines/src/main/java/com/instacart/formula/coroutines/FlowAction.kt
+++ b/formula-coroutines/src/main/java/com/instacart/formula/coroutines/FlowAction.kt
@@ -2,11 +2,14 @@ package com.instacart.formula.coroutines
 
 import com.instacart.formula.Action
 import com.instacart.formula.Cancelable
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.DelicateCoroutinesApi
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 /**
  * Adapter which allows creating Formula [Action] from Kotlin coroutine's. Take a
@@ -24,20 +27,10 @@ interface FlowAction<Event> : Action<Event> {
          * }
          * ```
          */
-        inline fun <Event> fromFlow(
-            scope: CoroutineScope = MainScope(),
-            crossinline create: () -> Flow<Event>
+        fun <Event> fromFlow(
+            create: () -> Flow<Event>
         ): Action<Event> {
-            return object : FlowAction<Event> {
-
-                override val scope: CoroutineScope = scope
-
-                override fun flow(): Flow<Event> {
-                    return create()
-                }
-
-                override fun key(): Any = Unit
-            }
+            return FlowActionImpl(null, create)
         }
 
         /**
@@ -51,31 +44,32 @@ interface FlowAction<Event> : Action<Event> {
          *
          * @param key Used to distinguish this [Action] from other actions.
          */
-        inline fun <Event> fromFlow(
-            scope: CoroutineScope = MainScope(),
+        fun <Event> fromFlow(
             key: Any?,
-            crossinline create: () -> Flow<Event>
+            create: () -> Flow<Event>
         ): Action<Event> {
-            return object : FlowAction<Event> {
-                override val scope: CoroutineScope = scope
-
-                override fun flow(): Flow<Event> {
-                    return create()
-                }
-
-                override fun key(): Any? = key
-            }
+            return FlowActionImpl(key, create)
         }
     }
 
     fun flow(): Flow<Event>
 
-    val scope: CoroutineScope
-
+    @OptIn(DelicateCoroutinesApi::class)
     override fun start(send: (Event) -> Unit): Cancelable? {
-        val job = flow()
-            .onEach { send(it) }
-            .launchIn(scope)
+        val job = GlobalScope.launch(start = CoroutineStart.UNDISPATCHED) {
+            withContext(Dispatchers.Unconfined) {
+                flow().collect { send(it) }
+            }
+        }
         return Cancelable(job::cancel)
     }
+}
+
+private data class FlowActionImpl<Event>(
+    private val key: Any?,
+    private val factory: () -> Flow<Event>
+) : FlowAction<Event> {
+    override fun flow(): Flow<Event> = factory()
+
+    override fun key(): Any? = key
 }
\ No newline at end of file
diff --git a/formula/src/test/java/com/instacart/formula/test/CoroutineTestableRuntime.kt b/formula/src/test/java/com/instacart/formula/test/CoroutineTestableRuntime.kt
index c931b518..9ba74fb0 100644
--- a/formula/src/test/java/com/instacart/formula/test/CoroutineTestableRuntime.kt
+++ b/formula/src/test/java/com/instacart/formula/test/CoroutineTestableRuntime.kt
@@ -10,7 +10,11 @@ import com.instacart.formula.coroutines.toFlow
 import com.instacart.formula.plugin.Dispatcher
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.DelicateCoroutinesApi
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
@@ -18,11 +22,13 @@ import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.launch
 import kotlinx.coroutines.test.TestCoroutineDispatcher
 import kotlinx.coroutines.test.TestCoroutineScope
 import kotlinx.coroutines.test.resetMain
 import kotlinx.coroutines.test.runBlockingTest
 import kotlinx.coroutines.test.setMain
+import kotlinx.coroutines.withContext
 import org.junit.rules.TestRule
 import org.junit.rules.TestWatcher
 import org.junit.runner.Description
@@ -70,20 +76,30 @@ object CoroutinesTestableRuntime : TestableRuntime {
 }
 
 private class FlowRelay : Relay {
-    private val sharedFlow = MutableSharedFlow<Unit>(0, 1)
+    private val sharedFlow = MutableSharedFlow<Unit>(0, 0)
 
     override fun action(): Action<Unit> = FlowAction.fromFlow { sharedFlow }
 
+    @OptIn(DelicateCoroutinesApi::class)
     override fun triggerEvent() {
-        sharedFlow.tryEmit(Unit)
+        GlobalScope.launch(start = CoroutineStart.UNDISPATCHED) {
+            withContext(Dispatchers.Unconfined) {
+                sharedFlow.emit(Unit)
+            }
+        }
     }
 }
 
 private class FlowStreamFormulaSubject : FlowFormula<String, Int>(), StreamFormulaSubject {
-    private val sharedFlow = MutableSharedFlow<Int>(0, extraBufferCapacity = 1, BufferOverflow.DROP_OLDEST)
+    private val sharedFlow = MutableSharedFlow<Int>(0, extraBufferCapacity = 0)
 
+    @OptIn(DelicateCoroutinesApi::class)
     override fun emitEvent(event: Int) {
-        sharedFlow.tryEmit(event)
+        GlobalScope.launch(start = CoroutineStart.UNDISPATCHED) {
+            withContext(Dispatchers.Unconfined) {
+                sharedFlow.emit(event)
+            }
+        }
     }
 
     override fun initialValue(input: String): Int = 0
@@ -133,28 +149,13 @@ private class CoroutineTestDelegate<Input : Any, Output : Any, FormulaT : IFormu
     }
 }
 
-@OptIn(ExperimentalStdlibApi::class)
+@OptIn(ExperimentalCoroutinesApi::class)
 private class CoroutineTestRule(
     val testCoroutineScope: TestCoroutineScope = TestCoroutineScope(TestCoroutineDispatcher())
 ) : TestWatcher() {
 
-    override fun starting(description: Description) {
-        Dispatchers.resetMain()
-        Dispatchers.setMain(testCoroutineScope.coroutineContext[CoroutineDispatcher]!!)
-        super.starting(description)
-    }
-
-    override fun apply(base: Statement, description: Description): Statement {
-        var result: Statement? = null
-        testCoroutineScope.runBlockingTest {
-            result = super.apply(base, description)
-        }
-        return result!!
-    }
-
-    override fun finished(description: Description?) {
+    override fun finished(description: Description) {
         super.finished(description)
-        Dispatchers.resetMain()
         testCoroutineScope.cleanupTestCoroutines()
     }
 }