From ade119f4a8b93b275a1ae879fec48ee2044eeb3e Mon Sep 17 00:00:00 2001
From: Michael Nebel <michaelnebel@github.com>
Date: Wed, 2 Feb 2022 11:25:34 +0100
Subject: [PATCH] C#: Add flow test cases for undetected value flow, when
 making variable bindinds in pattern matching.

---
 .../dataflow/patterns/PatternFlow.expected    |  5 ++
 .../dataflow/patterns/PatternFlow.ql          | 11 ++++
 .../dataflow/patterns/Patterns.cs             | 54 +++++++++++++++++++
 3 files changed, 70 insertions(+)
 create mode 100644 csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.expected
 create mode 100644 csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.ql
 create mode 100644 csharp/ql/test/library-tests/dataflow/patterns/Patterns.cs

diff --git a/csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.expected b/csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.expected
new file mode 100644
index 000000000000..f965891244cb
--- /dev/null
+++ b/csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.expected
@@ -0,0 +1,5 @@
+failures
+edges
+nodes
+subpaths
+#select
diff --git a/csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.ql b/csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.ql
new file mode 100644
index 000000000000..55578cf970c2
--- /dev/null
+++ b/csharp/ql/test/library-tests/dataflow/patterns/PatternFlow.ql
@@ -0,0 +1,11 @@
+/**
+ * @kind path-problem
+ */
+
+import csharp
+import DataFlow::PathGraph
+import TestUtilities.InlineFlowTest
+
+from DataFlow::PathNode source, DataFlow::PathNode sink, DefaultValueFlowConf conf
+where conf.hasFlowPath(source, sink)
+select sink, source, sink, "$@", source, source.toString()
diff --git a/csharp/ql/test/library-tests/dataflow/patterns/Patterns.cs b/csharp/ql/test/library-tests/dataflow/patterns/Patterns.cs
new file mode 100644
index 000000000000..37728dd40395
--- /dev/null
+++ b/csharp/ql/test/library-tests/dataflow/patterns/Patterns.cs
@@ -0,0 +1,54 @@
+using System;
+
+public record class RecordClass2(object Prop) { }
+
+public record class Nested(RecordClass2 Record) { }
+
+public class K
+{
+    private void M1()
+    {
+        var o = Source<object>(1);
+        var r = new RecordClass2(o);
+        if (r is RecordClass2 { Prop: object p })
+        {
+            Sink(p); // $ MISSING: hasValueFlow=1
+        }
+    }
+
+    private void M2()
+    {
+        var o = Source<object>(2);
+        var r = new RecordClass2(o);
+        switch (r)
+        {
+            case RecordClass2 { Prop: object p }:
+                Sink(p); // $ MISSING: hasValueFlow=2
+                break;
+        }
+    }
+
+    private void M3()
+    {
+        var o = Source<object>(3);
+        var s = new Nested(new RecordClass2(o));
+        if (s is Nested { Record: { Prop: object p } })
+        {
+            Sink(p); // $ MISSING: hasValueFlow=3
+        }
+    }
+
+    private void M4()
+    {
+        var o = Source<object>(4);
+        var s = new Nested(new RecordClass2(o));
+        if (s is Nested { Record.Prop: object p })
+        {
+            Sink(p); // $ MISSING: hasValueFlow=4
+        }
+    }
+
+    public static void Sink(object o) { }
+
+    static T Source<T>(object source) => throw null;
+}