test: Fix a MySql flicker by introducing an intentional delay (#2348)

tests/Agent/IntegrationTests/SharedApplications/Common/MultiFunctionApplicationHelpers/NetStandardLibraries/MySql/MySqlConnectorExerciser.cs

@@ -1,4 +1,4 @@
-// Copyright 2020 New Relic, Inc. All rights reserved.
+// Copyright 2020 New Relic, Inc. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 
@@ -39,6 +39,28 @@ public void ExecuteReader()
             });
         }
 
+        [LibraryMethod]
+        [Transaction]
+        [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]
+        public void ExecuteReaderWithDelay()
+        {
+            ExecuteCommand(command =>
+            {
+                var dates = new List<string>();
+                using (var reader = command.ExecuteReader())
+                {
+                    while (reader.Read())
+                    {
+                        dates.Add(reader.GetString(reader.GetOrdinal("_date")));
+                    }
+                }
+                string res = string.Join(",", dates);
+                ConsoleMFLogger.Info(res);
+                return res;
+            }, true); // add a delay to the query to make sure this is the slowest one that executes, helps test reliability
+        }
+
+
         [LibraryMethod]
         [Transaction]
         [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]
@@ -206,13 +228,14 @@ await ExecuteDbCommandAsync(async command =>
         }
 
         private const string Query = "SELECT _date FROM dates WHERE _date LIKE '2%' ORDER BY _date DESC LIMIT 1";
+        private const string QueryWithDelay = "SELECT SLEEP(2), _date FROM dates WHERE _date LIKE '2%' ORDER BY _date DESC LIMIT 1";
 
-        private string ExecuteCommand(Func<MySqlCommand, string> action)
+        private string ExecuteCommand(Func<MySqlCommand, string> action, bool delay = false)
         {
             string result;
 
             using (var connection = new MySqlConnection(MySqlTestConfiguration.MySqlConnectionString))
-            using (var command = new MySqlCommand(Query, connection))
+            using (var command = new MySqlCommand(delay ? QueryWithDelay : Query, connection))
             {
                 connection.Open();
                 result = action(command);

tests/Agent/IntegrationTests/UnboundedIntegrationTests/MySql/MySqlConnectorTests.cs

@@ -23,7 +23,7 @@ public abstract class MySqlConnectorTestBase<TFixture> : NewRelicIntegrationTest
 
         private readonly List<string> commandList = new List<string>()
         {
-            "ExecuteReader",
+            "ExecuteReaderWithDelay",
             "ExecuteScalar",
             "ExecuteNonQuery",
             "ExecuteReaderAsync",
@@ -56,9 +56,9 @@ protected MySqlConnectorTestBase(TFixture fixture, ITestOutputHelper output) : b
                     var configModifier = new NewRelicConfigModifier(configPath);
 
                     configModifier
-                        .ConfigureFasterMetricsHarvestCycle(10)
-                        .ConfigureFasterTransactionTracesHarvestCycle(10)
-                        .ConfigureFasterSqlTracesHarvestCycle(10)
+                        .ConfigureFasterMetricsHarvestCycle(30)
+                        .ConfigureFasterTransactionTracesHarvestCycle(30)
+                        .ConfigureFasterSqlTracesHarvestCycle(30)
                         .ForceTransactionTraces()
                         .SetLogLevel("finest");
 
@@ -74,8 +74,7 @@ protected MySqlConnectorTestBase(TFixture fixture, ITestOutputHelper output) : b
                 exerciseApplication: () =>
                 {
                     // Confirm transaction transform has completed before moving on to host application shutdown, and final sendDataOnExit harvest
-                    _fixture.AgentLog.WaitForLogLine(AgentLogBase.TransactionTransformCompletedLogLineRegex,
-                        TimeSpan.FromMinutes(2)); // must be 2 minutes since this can take a while.
+                    _fixture.AgentLog.WaitForLogLine(AgentLogBase.TransactionTransformCompletedLogLineRegex, TimeSpan.FromMinutes(2));
                     _fixture.AgentLog.WaitForLogLine(AgentLogBase.SqlTraceDataLogLineRegex, TimeSpan.FromMinutes(1));
                 }
             );
@@ -146,7 +145,7 @@ public void Test()
                     });
             }
 
-            var query = "SELECT _date FROM dates WHERE _date LIKE ? ORDER BY _date DESC LIMIT ?";
+            var queryWithDelay = "SELECT SLEEP(?), _date FROM dates WHERE _date LIKE ? ORDER BY _date DESC LIMIT ?";
 
             var expectedTransactionTraceSegments = new List<string> { "Datastore/statement/MySQL/dates/select" };
 
@@ -158,7 +157,7 @@ public void Test()
                 {
                     segmentName = "Datastore/statement/MySQL/dates/select",
                     parameterName = "sql",
-                    parameterValue = query
+                    parameterValue = queryWithDelay
                 },
                 new Assertions.ExpectedSegmentParameter
                 {
@@ -186,15 +185,11 @@ public void Test()
 
             var metrics = _fixture.AgentLog.GetMetrics().ToList();
 
-            // there should be only a single trace but we've found that the TransactionName isn't predictable enough
-            // (it's supposed to be the first query, but the assumption that the first query is always the slowest one doesn't
-            // hold universally). So we'll make sure there's just one trace and that the query, metricName and ExplainPlan properties are
-            // what we expect.
+            // there may be multiple traces, but we want the slowest one (by total call time) which is always the result of ExecuteReaderWithDelay
             var sqlTraces = _fixture.AgentLog.GetSqlTraces().ToList();
-            Assert.Single(sqlTraces);
+            var sqlTrace = sqlTraces.OrderByDescending(t => t.TotalCallTime).First();
 
-            var sqlTrace = sqlTraces.First();
-            Assert.Equal( query, sqlTrace.Sql );
+            Assert.Equal( queryWithDelay, sqlTrace.Sql );
             Assert.Equal("Datastore/statement/MySQL/dates/select", sqlTrace.DatastoreMetricName);
             Assert.True(sqlTrace.ParameterData.GetValueOrDefault("explain_plan") != null);