Fixed issue where no-op queries would never complete (#157)

* Fixed issue where no-op queries would never complete

* Changed approach to solving the race condition with no-op queries

* Addressing feedback

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/Contracts/QueryExecuteRequest.cs

@@ -29,7 +29,7 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts
     public class QueryExecuteResult
     {
         /// <summary>
-        /// Connection error messages. Optional, can be set to null to indicate no errors
+        /// Informational messages from the query runner. Optional, can be set to null.
         /// </summary>
         public string Messages { get; set; }
     }

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/QueryExecutionService.cs

@@ -424,6 +424,7 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
                     OwnerUri = executeParams.OwnerUri,
                     BatchSummaries = q.BatchSummaries
                 };
+
                 await requestContext.SendEvent(QueryExecuteCompleteEvent.Type, eventParams);
             };
 
@@ -470,9 +471,15 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
             query.Execute();
 
             // Send back a result showing we were successful
+            string messages = null;
+            if (query.Batches.Length == 0)
+            {
+                // If there were no batches to execute, send back an informational message that the commands were completed successfully
+                messages = SR.QueryServiceCompletedSuccessfully;
+            }
             await requestContext.SendResult(new QueryExecuteResult
             {
-                Messages = null
+                Messages = messages
             });
         }
 

test/Microsoft.SqlTools.ServiceLayer.TestDriver/Tests/QueryExecutionTests.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.SqlTools.ServiceLayer;
 using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
 using Microsoft.SqlTools.ServiceLayer.TestDriver.Utility;
 using Microsoft.SqlTools.ServiceLayer.Workspace.Contracts;
@@ -323,5 +324,36 @@ namespace Microsoft.SqlTools.ServiceLayer.TestDriver.Tests
                 await testHelper.Disconnect(queryTempFile.FilePath);
             }
         }
+
+        [Fact]
+        public async Task NoOpQueryReturnsMessage()
+        {
+            // Given queries that do nothing (no-ops)...
+            var queries = new string[]
+            {
+                "-- no-op",
+                "GO",
+                "GO -- no-op"
+            };
+
+            using (SelfCleaningTempFile queryTempFile = new SelfCleaningTempFile())
+            using (TestHelper testHelper = new TestHelper())
+            {
+                foreach (var query in queries)
+                {
+                    Assert.True(await testHelper.Connect(queryTempFile.FilePath, ConnectionTestUtils.LocalhostConnection));
+
+                    // If the queries are executed...
+                    var queryResult = await testHelper.RunQueryAsync(queryTempFile.FilePath, query);
+
+                    // Then I expect messages that the commands were completed successfully to be in the result
+                    Assert.NotNull(queryResult);
+                    Assert.NotNull(queryResult.Messages);
+                    Assert.Equal("Commands completed successfully.", queryResult.Messages);
+
+                    await testHelper.Disconnect(queryTempFile.FilePath);
+                }
+            }
+        }
     }
 }

test/Microsoft.SqlTools.ServiceLayer.TestDriver/Tests/TestHelper.cs

@@ -272,6 +272,23 @@ namespace Microsoft.SqlTools.ServiceLayer.TestDriver.Tests
                 return null;
             }
         }
+
+        /// <summary>
+        /// Run a query using a given connection bound to a URI. This method only waits for the initial response from query
+        /// execution (QueryExecuteResult). It is up to the caller to wait for the QueryExecuteCompleteEvent if they are interested.
+        /// </summary>
+        public async Task<QueryExecuteResult> RunQueryAsync(string ownerUri, string query, int timeoutMilliseconds = 5000)
+        {
+            WriteToFile(ownerUri, query);
+
+            var queryParams = new QueryExecuteParams
+            {
+                OwnerUri = ownerUri,
+                QuerySelection = null
+            };
+
+            return await Driver.SendRequest(QueryExecuteRequest.Type, queryParams);
+        }
         
         /// <summary>
         /// Request to cancel an executing query