Add a test to cover fix of #950

libraries/pushstore/impl/src/androidTest/kotlin/io/element/android/libraries/pushstore/impl/DefaultUserPushStoreFactoryTest.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.pushstore.impl
+
+import androidx.test.platform.app.InstrumentationRegistry
+import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.pushstore.api.UserPushStore
+import io.element.android.libraries.sessionstorage.test.observer.NoOpSessionObserver
+import kotlinx.coroutines.runBlocking
+import org.junit.Test
+import kotlin.concurrent.thread
+
+/**
+ * Note: to clear the emulator, invoke:
+ * adb uninstall io.element.android.libraries.push.pushstore.impl.test
+ */
+class DefaultUserPushStoreFactoryTest {
+
+    /**
+     * Ensure that creating UserPushStore is thread safe.
+     */
+    @Test
+    fun testParallelCreation() {
+        val context = InstrumentationRegistry.getInstrumentation().targetContext.applicationContext
+        val sessionId = SessionId("@alice:server.org")
+        val userPushStoreFactory = DefaultUserPushStoreFactory(context, NoOpSessionObserver())
+        var userPushStore1: UserPushStore? = null
+        val thread1 = thread {
+            userPushStore1 = userPushStoreFactory.create(sessionId)
+        }
+        var userPushStore2: UserPushStore? = null
+        val thread2 = thread {
+            userPushStore2 = userPushStoreFactory.create(sessionId)
+        }
+        thread1.join()
+        thread2.join()
+        runBlocking {
+            userPushStore1!!.areNotificationEnabledForDevice()
+            userPushStore2!!.areNotificationEnabledForDevice()
+        }
+    }
+}