Propagate nested coroutineBinding failures

Closes #128 and closes #133

Author: dbottillo

kotlin-result-coroutines/src/commonMain/kotlin/com/github/michaelbull/result/coroutines/CoroutineBinding.kt

@@ -56,7 +56,7 @@ public suspend inline fun <V, E> coroutineBinding(crossinline block: suspend Cor
             }
         }
     } catch (ex: BindCancellationException) {
-        receiver.result!!
+        receiver.result ?: throw ex
     }
 }
 

kotlin-result-coroutines/src/commonTest/kotlin/com/github/michaelbull/result/coroutines/AsyncCoroutineBindingTest.kt

@@ -164,4 +164,128 @@ class AsyncCoroutineBindingTest {
         assertTrue(yStateChange)
         assertFalse(zStateChange)
     }
+
+    @Test
+    fun shouldHandleNestedBindings() = runTest {
+        var xStateChange = false
+        var yStateChange = false
+        var zStateChange = false
+
+        suspend fun provideX(): Result<Int, BindingError> {
+            delay(1)
+            xStateChange = true
+            return Ok(1)
+        }
+
+        suspend fun provideXWrapped() = coroutineBinding {
+            provideX().bind()
+        }
+
+        suspend fun provideY(): Result<Int, BindingError.BindingErrorA> {
+            delay(20)
+            yStateChange = true
+            return Ok(1)
+        }
+
+        suspend fun provideYWrapped() = coroutineBinding {
+            provideY().bind()
+        }
+
+        suspend fun provideZ(): Result<Int, BindingError.BindingErrorB> {
+            delay(100)
+            zStateChange = true
+            return Ok(1)
+        }
+
+        suspend fun provideZWrapped() = coroutineBinding {
+            provideZ().bind()
+        }
+
+        val dispatcherA = StandardTestDispatcher(testScheduler)
+        val dispatcherB = StandardTestDispatcher(testScheduler)
+        val dispatcherC = StandardTestDispatcher(testScheduler)
+
+        val result: Result<Int, BindingError> = coroutineBinding {
+            val x = async(dispatcherA) { provideXWrapped().bind() }
+            val y = async(dispatcherB) { provideYWrapped().bind() }
+
+            testScheduler.advanceTimeBy(2)
+            testScheduler.runCurrent()
+
+            val z = async(dispatcherC) { provideZWrapped().bind() }
+
+            x.await() + y.await() + z.await()
+        }
+
+        assertEquals(
+            expected = Ok(3),
+            actual = result
+        )
+
+        assertTrue(xStateChange)
+        assertTrue(yStateChange)
+        assertTrue(zStateChange)
+    }
+
+    @Test
+    fun shouldHandleExceptionsWithNestedBindings() = runTest {
+        var xStateChange = false
+        var yStateChange = false
+        var zStateChange = false
+
+        suspend fun provideX(): Result<Int, BindingError> {
+            delay(1)
+            xStateChange = true
+            return Ok(1)
+        }
+
+        suspend fun provideXWrapped() = coroutineBinding {
+            provideX().bind()
+        }
+
+        suspend fun provideY(): Result<Int, BindingError.BindingErrorA> {
+            delay(20)
+            yStateChange = true
+            return Err(BindingError.BindingErrorA)
+        }
+
+        suspend fun provideYWrapped() = coroutineBinding {
+            provideY().bind()
+        }
+
+        suspend fun provideZ(): Result<Int, BindingError.BindingErrorB> {
+            delay(100)
+            zStateChange = true
+            return Ok(1)
+        }
+
+        suspend fun provideZWrapped() = coroutineBinding {
+            provideZ().bind()
+        }
+
+        val dispatcherA = StandardTestDispatcher(testScheduler)
+        val dispatcherB = StandardTestDispatcher(testScheduler)
+        val dispatcherC = StandardTestDispatcher(testScheduler)
+
+        val result: Result<Int, BindingError> = coroutineBinding {
+            val x = async(dispatcherA) { provideXWrapped().bind() }
+            val y = async(dispatcherB) { provideYWrapped().bind() }
+
+            testScheduler.advanceTimeBy(2)
+            testScheduler.runCurrent()
+
+            val z = async(dispatcherC) { provideZWrapped().bind() }
+
+            x.await() + y.await() + z.await()
+        }
+
+        assertEquals(
+            expected = Err(BindingError.BindingErrorA),
+            actual = result
+        )
+
+        assertTrue(xStateChange)
+        assertTrue(yStateChange)
+        assertFalse(zStateChange)
+    }
 }

kotlin-result-coroutines/src/commonTest/kotlin/com/github/michaelbull/result/coroutines/CoroutineBindingTest.kt

@@ -12,7 +12,11 @@ import kotlin.test.assertTrue
 
 class CoroutineBindingTest {
 
-    private object BindingError
+    private sealed interface BindingError {
+        data object BindingErrorA : BindingError
+        data object BindingErrorB : BindingError
+        data object BindingErrorC : BindingError
+    }
 
     @Test
     fun returnsOkIfAllBindsSuccessful() = runTest {
@@ -71,7 +75,7 @@ class CoroutineBindingTest {
 
         suspend fun provideY(): Result<Int, BindingError> {
             delay(1)
-            return Err(BindingError)
+            return Err(BindingError.BindingErrorA)
         }
 
         suspend fun provideZ(): Result<Int, BindingError> {
@@ -87,7 +91,7 @@ class CoroutineBindingTest {
         }
 
         assertEquals(
-            expected = Err(BindingError),
+            expected = Err(BindingError.BindingErrorA),
             actual = result,
         )
     }
@@ -107,13 +111,13 @@ class CoroutineBindingTest {
         suspend fun provideY(): Result<Int, BindingError> {
             delay(10)
             yStateChange = true
-            return Err(BindingError)
+            return Err(BindingError.BindingErrorA)
         }
 
         suspend fun provideZ(): Result<Int, BindingError> {
             delay(1)
             zStateChange = true
-            return Err(BindingError)
+            return Err(BindingError.BindingErrorA)
         }
 
         val result: Result<Int, BindingError> = coroutineBinding {
@@ -124,7 +128,7 @@ class CoroutineBindingTest {
         }
 
         assertEquals(
-            expected = Err(BindingError),
+            expected = Err(BindingError.BindingErrorA),
             actual = result,
         )
 
@@ -142,7 +146,7 @@ class CoroutineBindingTest {
 
         suspend fun provideY(): Result<String, BindingError> {
             delay(1)
-            return Err(BindingError)
+            return Err(BindingError.BindingErrorA)
         }
 
         suspend fun provideZ(): Result<Int, BindingError> {
@@ -158,8 +162,32 @@ class CoroutineBindingTest {
         }
 
         assertEquals(
-            expected = Err(BindingError),
+            expected = Err(BindingError.BindingErrorA),
             actual = result,
         )
     }
+
+    @Test
+    fun shouldHandleExceptionsWithMultipleNestedBindings() = runTest {
+        val result: Result<Int, BindingError> = coroutineBinding {
+            val b: Result<Int, BindingError> = coroutineBinding {
+                val c: Result<Int, BindingError> = coroutineBinding {
+                    Err(BindingError.BindingErrorC).bind()
+                }
+
+                assertEquals(Err(BindingError.BindingErrorC), c)
+
+                Ok(2).bind()
+            }
+
+            assertEquals(Ok(2), b)
+
+            Err(BindingError.BindingErrorB).bind()
+        }
+
+        assertEquals(
+            expected = Err(BindingError.BindingErrorB),
+            actual = result
+        )
+    }
 }