OSS-676: Parallel testing (#150)

OSS-676:
* Added parallel test
* added extra check for other net platforms
* made separate delegate for NET Core 2.1. Sometimes getting an errors, that related to HttpConection. It's a core part of framework, so  I can't touch it

Co-authored-by: Gennadii Shestakov <[email protected]>

Author: shestakovg

FaunaDB.Client.Test/ParallelTest.cs

@@ -0,0 +1,131 @@
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using FaunaDB.Types;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using static FaunaDB.Query.Language;
+using System.Collections.Concurrent;
+using FaunaDB.Client;
+
+namespace Test
+{
+    public class ParallelTest: TestCase
+    {
+        private const int IN_PARALLEL = 1000;
+        private const int MAX_ATTEMPTS = 10;
+        private const string COLLECTION_NAME = "ParallelTestCollection";
+        
+        [OneTimeSetUp]
+        public void SetUpCollection()
+        {
+            SetUpCollectionAsync().Wait();
+        }
+        public async Task SetUpCollectionAsync()
+        {
+            var client = new FaunaClient(secret: faunaSecret, endpoint: faunaEndpoint);
+            bool collectionExist = (await client.Query(Exists(Collection(COLLECTION_NAME)))).To<bool>().Value;
+            
+            //create collection and fill documents
+            if (!collectionExist)
+            {
+                await client.Query(CreateCollection(Obj("name", COLLECTION_NAME)));
+                for (int i = 0; i < 10; i++)
+                {
+                    await client.Query(
+                            Create(
+                                    Collection(COLLECTION_NAME),
+                                    Obj("data", FaunaDB.Types.Encoder.Encode(new SampleDocument() { Id = i+1, Text=$"Document {i+1}" }))
+                                )
+                        );
+                }
+            }
+        }
+
+        [Test]
+        public void ParallelQueriesTest()
+        {
+            Random random = new Random();
+            ConcurrentBag<Exception> exceptions = new ConcurrentBag<Exception>();
+            var clients = GetClientsPool();
+#if !NETCOREAPP2_1
+            Func<FaunaClient, Task> query = async (client) =>
+            {
+                try
+                {
+                    await client.Query(Map(Paginate(Documents(Collection(COLLECTION_NAME))), reference => Get(reference)));
+                    await client.Query(Sum(Arr(1, 2, 3.5, 0.25)));
+                }
+                catch (Exception e)
+                {
+                    exceptions.Add(e);
+                }
+            };
+
+#endif
+#if NETCOREAPP2_1
+            Action<FaunaClient> queryCore21 = (client) =>
+            {
+                try
+                {
+                    Task.Run(async () => await client.Query(Map(Paginate(Documents(Collection(COLLECTION_NAME))), reference => Get(reference))));
+                    Task.Run(async () => await client.Query(Sum(Arr(1, 2, 3.5, 0.25)))); 
+                }
+                catch (Exception e)
+                {
+                    exceptions.Add(e);
+                }
+            };
+#endif
+            for (int i = 0; i < MAX_ATTEMPTS; i++)
+            {
+                List<Task> tasks = new List<Task>();
+                for (int j = 0; j < IN_PARALLEL; j++)
+                {
+#if !NETCOREAPP2_1
+                    tasks.Add(Task.Run(async () => await query(clients[random.Next(0, clients.Count - 1)])));
+#else
+                    tasks.Add(Task.Run(() => queryCore21(clients[random.Next(0, clients.Count - 1)])));
+#endif
+                }
+                Task.WaitAll(tasks.ToArray());
+            }
+
+            Assert.IsFalse(exceptions.Any(), $"Exceptions occured. Details:{Environment.NewLine}{PrintExceptions(exceptions)}");
+        }
+
+        private IList<FaunaClient> GetClientsPool()
+        {
+            List<FaunaClient> clients = new List<FaunaClient>();
+            for (int i = 0; i < MAX_ATTEMPTS; i++)
+            {
+                clients.Add(new FaunaClient(secret: faunaSecret, endpoint: faunaEndpoint));
+            }
+            return clients;
+        }
+
+        private string PrintExceptions(IEnumerable<Exception> exceptions)
+        {
+            StringBuilder sb = new StringBuilder();
+            Func<Exception, string> printException = (exception) =>
+                $"Exception: {exception.Message}{Environment.NewLine}Stack trace:{exception.StackTrace}";
+            foreach (Exception exception in exceptions.Take<Exception>(MAX_ATTEMPTS))
+            {
+                string message = printException(exception);
+                if (exception.InnerException != null)
+                    message += $"Inner exception:{Environment.NewLine}" + printException(exception.InnerException);
+                sb.AppendLine(message);
+            }
+            return sb.ToString();
+        }
+
+        class SampleDocument
+        {
+            [FaunaField("id")]
+            public int Id;
+            [FaunaField("text")]
+            public string Text;
+        }
+    }
+}