checked a potential bug in the async functions, turns out it's a bug …

…in the Dapper library

Dapper.FastCrud.Tests/Relationships.feature

@@ -30,28 +30,28 @@ Scenario Outline: Query single relationship parent with children (external datab
 @InMemoryDatabase
 Scenario Outline: Query single relationship parents with children (in-memory database)
 	Given I have initialized a <database type> database
-	When I insert <entity count> workstation entities using <method type> methods
-	And I insert <entity count> employee entities parented to existing workstation entities using <method type> methods
+	When I insert <parent entity count> workstation entities using <method type> methods
+	And I insert <child entity count> employee entities parented to existing workstation entities using <method type> methods
 	And I query for all the workstation entities combined with the employee entities using <method type> methods
 	Then the queried workstation entities should be the same as the local ones
 	Examples: 
-	| database type | entity count | method type  |
-	| LocalDb       | 10           | synchronous  |
-	| LocalDb       | 10           | asynchronous |
+	| database type | parent entity count | child entity count | method type  |
+	| LocalDb       | 10                  | 20                 | synchronous  |
+	| LocalDb       | 10                  | 20                 | asynchronous |
 
 @ExternalDatabase
 Scenario Outline: Query single relationship parents with children (external database)
 	Given I have initialized a <database type> database
-	When I insert <entity count> workstation entities using <method type> methods
-	And I insert <entity count> employee entities parented to existing workstation entities using <method type> methods
+	When I insert <parent entity count> workstation entities using <method type> methods
+	And I insert <child entity count> employee entities parented to existing workstation entities using <method type> methods
 	And I query for all the workstation entities combined with the employee entities using <method type> methods
 	Then the queried workstation entities should be the same as the local ones
 	Examples: 
-	| database type | entity count | method type  |
-	| PostgreSql    | 10           | synchronous  |
-	| PostgreSql    | 10           | asynchronous |
-	| MySql         | 10           | synchronous  |
-	| MySql         | 10           | asynchronous |
+	| database type | parent entity count | child entity count | method type  |
+	| PostgreSql    | 10                  | 20                 | synchronous  |
+	| PostgreSql    | 10                  | 20                 | asynchronous |
+	| MySql         | 10                  | 20                 | synchronous  |
+	| MySql         | 10                  | 20                 | asynchronous |
 
 @InMemoryDatabase
 Scenario Outline: Count single relationship parents with children (in-memory database)

Dapper.FastCrud/SqlStatements/RelationshipSqlStatements.cs

@@ -111,6 +111,9 @@ public async Task<TEntity> SelectByIdAsync(IDbConnection connection, TEntity key
                 false,
                 statementOptions.Transaction, 
                 (int?)statementOptions.CommandTimeout?.TotalSeconds, relationshipInstanceBuilder);
+
+            // a problem in the Dapper library would cause this function to fail
+            // see https://github.com/StackExchange/dapper-dot-net/issues/596 for more info
             return this.FilterDuplicates(queriedEntityIdentities).SingleOrDefault();
         }
 
@@ -223,6 +226,9 @@ public async Task<IEnumerable<TEntity>> BatchSelectAsync(IDbConnection connectio
                               statementOptions.Transaction,
                               (int?)statementOptions.CommandTimeout?.TotalSeconds,
                               relationshipInstanceBuilder);
+
+            // a problem in the Dapper library would cause this function to fail
+            // see https://github.com/StackExchange/dapper-dot-net/issues/596 for more info
             return this.FilterDuplicates(queriedEntityIdentities);
         }