Refactor coroutine testing setup (#1583)

* coroutine-utils: init

* coroutine-utils-testing: init

* format-common: switch over to using DispatcherProvider

* Convert Binds method to an extension function

* Add Dispatcher module

1 files changed, 45 insertions, 0 deletions

diff --git a/coroutine-utils-testing/src/main/kotlin/dev/msfjarvis/aps/test/CoroutineTestRule.kt b/coroutine-utils-testing/src/main/kotlin/dev/msfjarvis/aps/test/CoroutineTestRule.kt
new file mode 100644
index 00000000..fa4a2d41
--- /dev/null
+++ b/coroutine-utils-testing/src/main/kotlin/dev/msfjarvis/aps/test/CoroutineTestRule.kt
@@ -0,0 +1,45 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.test
+
+import dev.msfjarvis.aps.util.coroutines.DispatcherProvider
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.TestCoroutineScheduler
+import kotlinx.coroutines.test.TestDispatcher
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.setMain
+import org.junit.rules.TestWatcher
+import org.junit.runner.Description
+
+/**
+ * JUnit [TestWatcher] to correctly handle setting and resetting a given [testDispatcher] for tests.
+ */
+@ExperimentalCoroutinesApi
+public class CoroutineTestRule(
+  public val testDispatcher: TestDispatcher = UnconfinedTestDispatcher(TestCoroutineScheduler()),
+) : TestWatcher() {
+
+  public val testDispatcherProvider: DispatcherProvider =
+    object : DispatcherProvider {
+      override fun default(): CoroutineDispatcher = testDispatcher
+      override fun io(): CoroutineDispatcher = testDispatcher
+      override fun main(): CoroutineDispatcher = testDispatcher
+      override fun unconfined(): CoroutineDispatcher = testDispatcher
+    }
+
+  override fun starting(description: Description?) {
+    super.starting(description)
+    Dispatchers.setMain(testDispatcher)
+  }
+
+  override fun finished(description: Description?) {
+    super.finished(description)
+    Dispatchers.resetMain()
+  }
+}