Increase coroutines module coverage. (#386)

formula-coroutines/build.gradle.kts

@@ -17,4 +17,5 @@ dependencies {
     testImplementation(libs.truth)
     testImplementation(libs.junit)
     testImplementation(libs.coroutines.test)
+    testImplementation(libs.turbine)
 }

formula-coroutines/src/main/java/com/instacart/formula/coroutines/FlowRuntime.kt

@@ -20,7 +20,7 @@ object FlowRuntime {
         formula: IFormula<Input, Output>,
         config: RuntimeConfig?,
     ): Flow<Output> {
-        return callbackFlow<Output> {
+        val callbackFlow = callbackFlow {
             val runtime = FormulaRuntime(
                 formula = formula,
                 onOutput = this::trySendBlocking,
@@ -33,6 +33,7 @@ object FlowRuntime {
             awaitClose {
                 runtime.terminate()
             }
-        }.distinctUntilChanged()
+        }
+        return callbackFlow.distinctUntilChanged()
     }
 }

formula-coroutines/src/test/java/com/instacart/formula/coroutines/FlowActionTest.kt

@@ -0,0 +1,20 @@
+package com.instacart.formula.coroutines
+
+import com.google.common.truth.Truth.assertThat
+import kotlinx.coroutines.flow.flowOf
+import org.junit.Test
+
+class FlowActionTest {
+
+    @Test
+    fun `default key is null`() {
+        val action = FlowAction.fromFlow { flowOf("") }
+        assertThat(action.key()).isNull()
+    }
+
+    @Test
+    fun `specified key`() {
+        val action = FlowAction.fromFlow("unique-key") { flowOf("") }
+        assertThat(action.key()).isEqualTo("unique-key")
+    }
+}

formula-coroutines/src/test/java/com/instacart/formula/coroutines/FlowRuntimeTest.kt

@@ -0,0 +1,136 @@
+package com.instacart.formula.coroutines
+
+import app.cash.turbine.test
+import com.google.common.truth.Truth
+import com.instacart.formula.Evaluation
+import com.instacart.formula.RuntimeConfig
+import com.instacart.formula.Snapshot
+import com.instacart.formula.StatelessFormula
+import com.instacart.formula.test.CountingInspector
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+
+class FlowRuntimeTest {
+
+    @Test
+    fun `toFlow with unit input and no config`() {
+        val formula = object : StatelessFormula<Unit, String>() {
+            override fun Snapshot<Unit, Unit>.evaluate(): Evaluation<String> {
+                return Evaluation("output")
+            }
+        }
+
+        runTest {
+            formula.toFlow().test {
+                Truth.assertThat(awaitItem()).isEqualTo("output")
+            }
+        }
+    }
+
+    @Test
+    fun `toFlow with unit input and config`() {
+        val formula = object : StatelessFormula<Unit, String>() {
+            override fun Snapshot<Unit, Unit>.evaluate(): Evaluation<String> {
+                return Evaluation("output")
+            }
+        }
+
+        val inspector = CountingInspector()
+        runTest {
+            formula.toFlow(config = RuntimeConfig(inspector = inspector)).test {
+                Truth.assertThat(awaitItem()).isEqualTo("output")
+            }
+        }
+        inspector.assertEvaluationCount(1)
+    }
+
+    @Test
+    fun `toFlow with input value and no config`() {
+        val formula = object : StatelessFormula<String, String>() {
+            override fun Snapshot<String, Unit>.evaluate(): Evaluation<String> {
+                return Evaluation(input)
+            }
+        }
+
+        runTest {
+            formula.toFlow("output").test {
+                Truth.assertThat(awaitItem()).isEqualTo("output")
+            }
+        }
+    }
+
+    @Test
+    fun `toFlow with input value and config`() {
+        val formula = object : StatelessFormula<String, String>() {
+            override fun Snapshot<String, Unit>.evaluate(): Evaluation<String> {
+                return Evaluation(input)
+            }
+        }
+
+        val inspector = CountingInspector()
+        runTest {
+            formula.toFlow("output", RuntimeConfig(inspector = inspector)).test {
+                Truth.assertThat(awaitItem()).isEqualTo("output")
+            }
+        }
+        inspector.assertEvaluationCount(1)
+    }
+
+    @Test
+    fun `toFlow with input flow and no config`() {
+        val formula = object : StatelessFormula<String, String>() {
+            override fun Snapshot<String, Unit>.evaluate(): Evaluation<String> {
+                return Evaluation(input)
+            }
+        }
+
+        runTest {
+            formula.toFlow(flowOf("output", "output-2")).test {
+                Truth.assertThat(awaitItem()).isEqualTo("output")
+                Truth.assertThat(awaitItem()).isEqualTo("output-2")
+            }
+        }
+    }
+
+    @Test
+    fun `toFlow with input flow and config`() {
+        val formula = object : StatelessFormula<String, String>() {
+            override fun Snapshot<String, Unit>.evaluate(): Evaluation<String> {
+                return Evaluation(input)
+            }
+        }
+
+        val inspector = CountingInspector()
+        runTest {
+            formula.toFlow(
+                input = flowOf("output", "output-2"),
+                config = RuntimeConfig(inspector = inspector),
+            ).test {
+                Truth.assertThat(awaitItem()).isEqualTo("output")
+                Truth.assertThat(awaitItem()).isEqualTo("output-2")
+            }
+        }
+        inspector.assertEvaluationCount(2)
+    }
+
+    @Test
+    fun `toFlow with input flow with duplicate values`() {
+        val formula = object : StatelessFormula<String, String>() {
+            override fun Snapshot<String, Unit>.evaluate(): Evaluation<String> {
+                return Evaluation(input)
+            }
+        }
+
+        val inspector = CountingInspector()
+        runTest {
+            formula.toFlow(
+                input = flowOf("output", "output", "output"),
+                config = RuntimeConfig(inspector = inspector),
+            ).test {
+                Truth.assertThat(awaitItem()).isEqualTo("output")
+            }
+        }
+        inspector.assertEvaluationCount(1)
+    }
+}

gradle/libs.versions.toml

@@ -32,6 +32,7 @@ kotlin-reflect = { module = "org.jetbrains.kotlin:kotlin-reflect", version.ref =
 
 coroutines = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-core", version.ref = "coroutines" }
 coroutines-test = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-test", version.ref = "coroutines" }
+turbine = { module = "app.cash.turbine:turbine", version="1.1.0" }
 
 compose-ui = { module = "androidx.compose.ui:ui", version.ref = "compose" }
 compose-foundation = { module = "androidx.compose.foundation:foundation", version.ref = "compose" }