C#: Add some test cases for inheritance.

Author: michaelnebel

csharp/ql/test/utils/model-generator/CaptureSummaryModels.expected

@@ -1,4 +1,5 @@
 | NoSummaries;PublicClassFlow;false;PublicReturn;(System.Int32);Argument[0];ReturnValue;taint |
+| Summaries;BaseClassFlow;true;ReturnParam;(System.Int32);Argument[0];ReturnValue;taint |
 | Summaries;BasicFlow;false;ReturnField;();Argument[Qualifier];ReturnValue;taint |
 | Summaries;BasicFlow;false;ReturnParam0;(System.String,System.Object);Argument[0];ReturnValue;taint |
 | Summaries;BasicFlow;false;ReturnParam1;(System.String,System.Object);Argument[1];ReturnValue;taint |
@@ -17,6 +18,9 @@
 | Summaries;CollectionFlow;false;ReturnArrayElement;(System.Int32[]);Argument[0].Element;ReturnValue;taint |
 | Summaries;CollectionFlow;false;ReturnFieldInAList;();Argument[Qualifier];ReturnValue;taint |
 | Summaries;CollectionFlow;false;ReturnListElement;(System.Collections.Generic.List<System.Object>);Argument[0].Element;ReturnValue;taint |
+| Summaries;DerivedClass1Flow;false;ReturnParam1;(System.Int32,System.Int32);Argument[1];ReturnValue;taint |
+| Summaries;DerivedClass2Flow;false;ReturnParam0;(System.Int32,System.Int32);Argument[0];ReturnValue;taint |
+| Summaries;DerivedClass2Flow;false;ReturnParam;(System.Int32);Argument[0];ReturnValue;taint |
 | Summaries;GenericFlow<>;false;AddFieldToGenericList;(System.Collections.Generic.List<T>);Argument[Qualifier];Argument[0].Element;taint |
 | Summaries;GenericFlow<>;false;AddToGenericList<>;(System.Collections.Generic.List<S>,S);Argument[1];Argument[0].Element;taint |
 | Summaries;GenericFlow<>;false;ReturnFieldInGenericList;();Argument[Qualifier];ReturnValue;taint |

csharp/ql/test/utils/model-generator/Summaries.cs

@@ -163,3 +163,32 @@ public void AddToGenericList<S>(List<S> input, S data)
         input.Add(data);
     }
 }
+
+public abstract class BaseClassFlow
+{
+    public virtual int ReturnParam(int input)
+    {
+        return input;
+    }
+}
+
+public class DerivedClass1Flow : BaseClassFlow
+{
+    public int ReturnParam1(int input0, int input1)
+    {
+        return input1;
+    }
+}
+
+public class DerivedClass2Flow : BaseClassFlow
+{
+    public override int ReturnParam(int input)
+    {
+        return input;
+    }
+
+    public int ReturnParam0(int input0, int input1)
+    {
+        return input0;
+    }
+}