Make test timeouts less sensitive to slow CI environments.

Helps address #246.

Author: bgrainger

tests/SideBySide/AppConfig.cs

@@ -65,6 +65,10 @@ public static MySqlConnectionStringBuilder CreateConnectionStringBuilder()
 			return new MySqlConnectionStringBuilder(ConnectionString);
 		}
 
+		// tests can run extremely slowly on Appveyor (and slightly slower under Travis)
+		public static int TimeoutDelayFactor { get; } = Environment.GetEnvironmentVariable("APPVEYOR") == "True" ? 6 :
+			Environment.GetEnvironmentVariable("TRAVIS") == "true" ? 3 : 1;
+
 		private static string GetCodeRootPath()
 		{
 #if NET46

tests/SideBySide/CancelTests.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System;
 using System.Data;
 using System.Diagnostics;
 using System.Linq;
@@ -112,7 +111,7 @@ public void CancelCommandBeforeRead()
 						Assert.Equal((int) MySqlErrorCode.QueryInterrupted, ex.Number);
 					}
 					Assert.False(reader.NextResult());
-					Assert.InRange(stopwatch.ElapsedMilliseconds, 0, 1000 * c_ciDelayFactor);
+					TestUtilities.AssertDuration(stopwatch, 0, 1000);
 					Assert.InRange(rows, 0, 10000000);
 				}
 			}
@@ -174,7 +173,7 @@ public void DapperQueryMultiple()
 				stopwatch = Stopwatch.StartNew();
 			}
 			stopwatch.Stop();
-			Assert.InRange(stopwatch.ElapsedMilliseconds, 0, 1000 * c_ciDelayFactor);
+			TestUtilities.AssertDuration(stopwatch, 0, 1000);
 		}
 
 #if !BASELINE
@@ -294,7 +293,7 @@ public async Task CancelSlowQueryWithTokenAfterExecuteReader()
 				var stopwatch = Stopwatch.StartNew();
 				using (var reader = await cmd.ExecuteReaderAsync(cts.Token))
 				{
-					Assert.InRange(stopwatch.ElapsedMilliseconds, 450, 750 * c_ciDelayFactor);
+					TestUtilities.AssertDuration(stopwatch, 450, 300);
 
 					var rows = 0;
 					try
@@ -329,7 +328,7 @@ public async Task CancelSlowQueryWithTokenAfterNextResult()
 					// the call to NextResult should block until the token is cancelled
 					var stopwatch = Stopwatch.StartNew();
 					Assert.True(await reader.NextResultAsync(cts.Token));
-					Assert.InRange(stopwatch.ElapsedMilliseconds, 450, 750 * c_ciDelayFactor);
+					TestUtilities.AssertDuration(stopwatch, 450, 300);
 
 					int rows = 0;
 					try
@@ -393,10 +392,6 @@ private static CancellationToken GetCanceledToken()
 		const string c_slowQuery = @"select * from integers a join integers b join integers c join integers d join integers e join integers f join integers g join integers h
 where sqrt(a.value) + sqrt(b.value) + sqrt(c.value) + sqrt(d.value) + sqrt(e.value) + sqrt(f.value) + sqrt(g.value) + sqrt(h.value) = 20;";
 
-		// tests can run extremely slowly on Appveyor (and slightly slower under Travis)
-		static readonly int c_ciDelayFactor = Environment.GetEnvironmentVariable("APPVEYOR") == "True" ? 10 :
-			Environment.GetEnvironmentVariable("TRAVIS") == "true" ? 3 : 1;
-
 		readonly DatabaseFixture m_database;
 	}
 }

tests/SideBySide/ConnectSync.cs

@@ -218,7 +218,7 @@ public void ConnectTimeout()
 				var stopwatch = Stopwatch.StartNew();
 				Assert.Throws<MySqlException>(() => connection.Open());
 				stopwatch.Stop();
-				Assert.InRange(stopwatch.ElapsedMilliseconds, 2800, 3500);
+				TestUtilities.AssertDuration(stopwatch, 2900, 200);
 			}
 		}
 

tests/SideBySide/ConnectionPool.cs

@@ -123,7 +123,7 @@ public async Task ExhaustConnectionPoolWithTimeout()
 				var stopwatch = Stopwatch.StartNew();
 				Assert.Throws<MySqlException>(() => extraConnection.Open());
 				stopwatch.Stop();
-				Assert.InRange(stopwatch.ElapsedMilliseconds, 4500, 5500);
+				Assert.InRange(stopwatch.ElapsedMilliseconds, 4500, 6000);
 			}
 
 			foreach (var connection in connections)

tests/SideBySide/TestUtilities.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Globalization;
 using Xunit;
 
@@ -21,6 +22,16 @@ public static void AssertEqual(byte[] expected, byte[] actual)
 			}
 		}
 
+		/// <summary>
+		/// Asserts that <paramref name="stopwatch"/> is in the range [minimumMilliseconds, minimumMilliseconds + lengthMilliseconds].
+		/// </summary>
+		/// <remarks>This method applies a scaling factor for delays encountered under Continuous Integration environments.</remarks>
+		public static void AssertDuration(Stopwatch stopwatch, int minimumMilliseconds, int lengthMilliseconds)
+		{
+			var elapsed = stopwatch.ElapsedMilliseconds;
+			Assert.InRange(elapsed, minimumMilliseconds, minimumMilliseconds + lengthMilliseconds * AppConfig.TimeoutDelayFactor);
+		}
+
 		public static Version ParseServerVersion(string serverVersion)
 		{
 			// copied from MySql.Data.MySqlClient.ServerVersion