C#: Add test cases for ref fields.

Author: michaelnebel

csharp/ql/test/library-tests/csharp11/Struct.cs_

@@ -0,0 +1,15 @@
+// TODO: Test needs to be enabled when .NET 7 is used as the runtime.
+namespace structassembly;
+
+public class MyEmptyClass { }
+
+public ref struct RefStruct
+{
+    public int MyInt;
+    public ref byte MyByte;
+    public ref object MyObject;
+    internal ref MyEmptyClass MyEmptyClass;
+    public ref readonly byte MyReadonlyByte;
+    public readonly ref object MyReadonlyObject;
+    public readonly ref readonly string MyReadonlyString;
+}

csharp/ql/test/library-tests/csharp11/cil/Struct.cs_

@@ -0,0 +1,14 @@
+namespace structassembly;
+
+public class MyEmptyClass { }
+
+public ref struct RefStruct
+{
+    public int MyInt;
+    public ref byte MyByte;
+    public ref object MyObject;
+    internal ref MyEmptyClass MyEmptyClass;
+    public ref readonly byte MyReadonlyByte;
+    public readonly ref object MyReadonlyObject;
+    public readonly ref readonly string MyReadonlyString;
+}

csharp/ql/test/library-tests/csharp11/cil/refField.expected

@@ -0,0 +1,6 @@
+| file://:0:0:0:0 | MyByte | Byte |
+| file://:0:0:0:0 | MyEmptyClass | MyEmptyClass |
+| file://:0:0:0:0 | MyObject | Object |
+| file://:0:0:0:0 | MyReadonlyByte | Byte |
+| file://:0:0:0:0 | MyReadonlyObject | Object |
+| file://:0:0:0:0 | MyReadonlyString | String |

csharp/ql/test/library-tests/csharp11/cil/refField.ql

@@ -0,0 +1,5 @@
+import cil
+
+query predicate cilfields(CIL::Field f, string type) {
+  f.isRef() and type = f.getType().toString() and f.getDeclaringType().getName() = "RefStruct"
+}

csharp/ql/test/library-tests/csharp11/cil/structassembly.dll

@@ -0,0 +1,3 @@
+reffields
+readonlyreffields
+readonlyfield

csharp/ql/test/library-tests/csharp11/refField.expected

@@ -0,0 +1,16 @@
+import csharp
+
+query predicate reffields(Field f) {
+  f.getFile().getStem() = "Struct" and
+  f.isRef()
+}
+
+query predicate readonlyreffields(Field f) {
+  f.getFile().getStem() = "Struct" and
+  f.isReadonlyRef()
+}
+
+query predicate readonlyfield(Field f) {
+  f.getFile().getStem() = "Struct" and
+  f.isReadOnly()
+}