From ed258551fde3017243f39701b2ef1f114d24ad95 Mon Sep 17 00:00:00 2001
From: Thijs Koot <thijs.koot@kadenza.nl>
Date: Thu, 12 Dec 2019 19:36:12 +0100
Subject: [PATCH] fix and new test for #180

---
 Snowflake.Data.Tests/SFDbCommandIT.cs       | 16 +++++++++++++++
 Snowflake.Data/Client/SnowflakeDbCommand.cs | 22 +++++++++++++++++----
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/Snowflake.Data.Tests/SFDbCommandIT.cs b/Snowflake.Data.Tests/SFDbCommandIT.cs
index 8e241ee14..06a314ace 100755
--- a/Snowflake.Data.Tests/SFDbCommandIT.cs
+++ b/Snowflake.Data.Tests/SFDbCommandIT.cs
@@ -483,5 +483,21 @@ public void TestExecuteScalarNull()
                 conn.Close();
             }
         }
+
+        [Test]
+        public void TestCreateCommandBeforeOpeningConnection()
+        {
+            using(var conn = new SnowflakeDbConnection())
+            {
+                conn.ConnectionString = ConnectionString;
+                
+                using(var command = conn.CreateCommand())
+                {
+                    conn.Open();
+                    command.CommandText = "select 1";
+                    Assert.DoesNotThrow(() => command.ExecuteNonQuery());
+                }
+            }
+        }
     }
 }
diff --git a/Snowflake.Data/Client/SnowflakeDbCommand.cs b/Snowflake.Data/Client/SnowflakeDbCommand.cs
index 59c18dfcc..14ac79950 100755
--- a/Snowflake.Data/Client/SnowflakeDbCommand.cs
+++ b/Snowflake.Data/Client/SnowflakeDbCommand.cs
@@ -37,7 +37,6 @@ public SnowflakeDbCommand(SnowflakeDbConnection connection)
         {
             logger.Debug("Constucting SnowflakeDbCommand class");
             this.connection = connection;
-            this.sfStatement = new SFStatement(connection.SfSession);
             // by default, no query timeout
             this.CommandTimeout = 0;
             parameterCollection = new SnowflakeDbParameterCollection();
@@ -45,7 +44,7 @@ public SnowflakeDbCommand(SnowflakeDbConnection connection)
 
         public override string CommandText
         {
-            get;  set;
+            get; set;
         }
 
         public override int CommandTimeout
@@ -150,9 +149,10 @@ protected override DbTransaction DbTransaction
 
         public override void Cancel()
         {
-            sfStatement.Cancel();
+            // doesn't throw exception when sfStatement is null
+            sfStatement?.Cancel();
         }
-        
+
         public override int ExecuteNonQuery()
         {
             logger.Debug($"ExecuteNonQuery, command: {CommandText}");
@@ -282,13 +282,27 @@ private static Dictionary<string, BindingDTO> convertToBindList(List<SnowflakeDb
             }
         }
 
+        private void SetStatement() 
+        {
+            var session = (connection as SnowflakeDbConnection).SfSession;
+
+            // SetStatement is called when executing a command. If SfSession is null
+            // the connection has never been opened. Exception might be a bit vague.
+            if (session == null)
+                throw new Exception("Can't execute command when connection has never been opened");
+
+            this.sfStatement = new SFStatement(session);
+        }
+
         private SFBaseResultSet ExecuteInternal(bool describeOnly = false)
         {
+            SetStatement();
             return sfStatement.Execute(CommandTimeout, CommandText, convertToBindList(parameterCollection.parameterList), describeOnly);
         }
 
         private Task<SFBaseResultSet> ExecuteInternalAsync(CancellationToken cancellationToken, bool describeOnly = false)
         {
+            SetStatement();
             return sfStatement.ExecuteAsync(CommandTimeout, CommandText, convertToBindList(parameterCollection.parameterList), describeOnly, cancellationToken);
         }
     }