Coroutine tests (#185)

* Add some coroutine tests for implicit cancellation

* Create util test and new helper methods

* Remove coroutinescope extension from withcontext

* Update dependencies

1 files changed, 60 insertions, 0 deletions

diff --git a/core/src/main/kotlin/ca/allanwang/kau/utils/CoroutineUtils.kt b/core/src/main/kotlin/ca/allanwang/kau/utils/CoroutineUtils.kt
new file mode 100644
index 0000000..032c407
--- /dev/null
+++ b/core/src/main/kotlin/ca/allanwang/kau/utils/CoroutineUtils.kt
@@ -0,0 +1,60 @@
+package ca.allanwang.kau.utils
+
+import android.content.Context
+import android.os.Handler
+import android.os.Looper
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.android.asCoroutineDispatcher
+import kotlinx.coroutines.async
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+
+object ContextHelper : CoroutineScope {
+
+    val looper = Looper.getMainLooper()
+
+    val handler = Handler(looper)
+
+    /**
+     * Creating dispatcher from main handler to avoid IO
+     * See https://github.com/Kotlin/kotlinx.coroutines/issues/878
+     */
+    val dispatcher = handler.asCoroutineDispatcher("kau-main")
+
+    override val coroutineContext: CoroutineContext get() = dispatcher
+}
+
+/**
+ * Most context items implement [CoroutineScope] by default.
+ * We will add a fallback just in case.
+ * It is expected that the scope returned always has the Android main dispatcher as part of the context.
+ */
+internal inline val Context.ctxCoroutine: CoroutineScope
+    get() = this as? CoroutineScope ?: ContextHelper
+
+/**
+ * Calls [launch] with an explicit dispatcher for Android's main thread
+ */
+fun CoroutineScope.launchMain(
+    context: CoroutineContext = EmptyCoroutineContext,
+    start: CoroutineStart = CoroutineStart.DEFAULT,
+    block: suspend CoroutineScope.() -> Unit
+) = launch(ContextHelper.dispatcher + context, start, block)
+
+/**
+ * Calls [async] with an explicit dispatcher for Android's main thread
+ */
+fun CoroutineScope.asyncMain(
+    context: CoroutineContext = EmptyCoroutineContext,
+    start: CoroutineStart = CoroutineStart.DEFAULT,
+    block: suspend CoroutineScope.() -> Unit
+) = async(ContextHelper.dispatcher + context, start, block)
+
+/**
+ * Calls [withContext] with an explicit dispatcher for Android's main thread
+ */
+suspend fun <T> withMainContext(block: suspend CoroutineScope.() -> T) =
+    withContext(ContextHelper.dispatcher, block)