C#: Add ContentDataFlow test

csharp/ql/test/library-tests/dataflow/content/ContentFlow.cs

@@ -0,0 +1,31 @@
+using System;
+
+public class ContentFlow
+{
+    public class A
+    {
+        public A FieldA;
+        public B FieldB;
+    }
+    public class B
+    {
+        public A FieldA;
+        public B FieldB;
+    }
+
+    public void M(A a, B b)
+    {
+        var a1 = new A();
+        Sink(a1.FieldA.FieldB);
+
+        a.FieldA.FieldB = new B();
+        Sink(a);
+
+        var a2 = new A();
+        b.FieldB.FieldA = a2.FieldB.FieldA;
+        Sink(b);
+    }
+
+    public static void Sink<T>(T t) { }
+
+}

csharp/ql/test/library-tests/dataflow/content/ContentFlow.expected

@@ -0,0 +1,3 @@
+| ContentFlow.cs:18:18:18:24 | object creation of type A | field FieldB.field FieldA. | ContentFlow.cs:19:14:19:29 | access to field FieldB |  | true |
+| ContentFlow.cs:21:27:21:33 | object creation of type B |  | ContentFlow.cs:22:14:22:14 | access to parameter a | field FieldA.field FieldB. | true |
+| ContentFlow.cs:24:18:24:24 | object creation of type A | field FieldA.field FieldB. | ContentFlow.cs:26:14:26:14 | access to parameter b | field FieldB.field FieldA. | true |

csharp/ql/test/library-tests/dataflow/content/ContentFlow.ql

@@ -0,0 +1,23 @@
+import csharp
+import semmle.code.csharp.dataflow.internal.ContentDataFlow
+
+class Conf extends ContentDataFlow::Configuration {
+  Conf() { this = "ContentFlowConf" }
+
+  override predicate isSource(DataFlow::Node src) { src.asExpr() instanceof ObjectCreation }
+
+  override predicate isSink(DataFlow::Node sink) {
+    exists(MethodCall mc |
+      mc.getTarget().hasUndecoratedName("Sink") and
+      mc.getAnArgument() = sink.asExpr()
+    )
+  }
+
+  override int accessPathLimit() { result = 2 }
+}
+
+from
+  Conf conf, ContentDataFlow::Node source, ContentDataFlow::AccessPath sourceAp,
+  ContentDataFlow::Node sink, ContentDataFlow::AccessPath sinkAp, boolean preservesValue
+where conf.hasFlow(source, sourceAp, sink, sinkAp, preservesValue)
+select source, sourceAp, sink, sinkAp, preservesValue