C#: Add some more testcases for flow summary generation.

Author: michaelnebel

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

@@ -1,7 +1,11 @@
+| Summaries;BasicFlow;false;AssignFieldToArray;(System.Object[]);Argument[Qualifier];Argument[0].Element;taint |
 | Summaries;BasicFlow;false;AssignToArray;(System.Int32,System.Int32[]);Argument[0];Argument[1].Element;taint |
 | Summaries;BasicFlow;false;ReturnArrayElement;(System.Int32[]);Argument[0].Element;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 |
 | Summaries;BasicFlow;false;ReturnParamMultiple;(System.Object,System.Object);Argument[0];ReturnValue;taint |
 | Summaries;BasicFlow;false;ReturnParamMultiple;(System.Object,System.Object);Argument[1];ReturnValue;taint |
+| Summaries;BasicFlow;false;ReturnSubstring;(System.String);Argument[0];ReturnValue;taint |
 | Summaries;BasicFlow;false;ReturnThis;(System.Object);Argument[Qualifier];ReturnValue;value |
+| Summaries;BasicFlow;false;SetField;(System.String);Argument[0];Argument[Qualifier];taint |

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

@@ -4,6 +4,8 @@ namespace Summaries;
 
 public class BasicFlow
 {
+    private string tainted;
+
     public BasicFlow ReturnThis(object input)
     {
         return this;
@@ -24,6 +26,11 @@ public object ReturnParamMultiple(object input0, object input1)
         return (System.DateTime.Now.DayOfWeek == System.DayOfWeek.Monday) ? input0 : input1;
     }
 
+    public string ReturnSubstring(string s)
+    {
+        return s.Substring(0, 1);
+    }
+
     public int ReturnArrayElement(int[] input)
     {
         return input[0];
@@ -33,4 +40,19 @@ public void AssignToArray(int data, int[] target)
     {
         target[0] = data;
     }
+
+    public void SetField(string s)
+    {
+        tainted = s;
+    }
+
+    public string ReturnField()
+    {
+        return tainted;
+    }
+
+    public void AssignFieldToArray(object[] target)
+    {
+        target[0] = tainted;
+    }
 }