C#: C#9 Add target typed conditional tests

Author: tamasvajk

csharp/ql/test/library-tests/csharp9/PrintAst.expected

@@ -335,6 +335,58 @@ ParenthesizedPattern.cs:
 #   27|               0: [TypeAccessPatternExpr] access to type String
 #   27|                 0: [TypeMention] string
 #   27|               2: [IntLiteral] 5
+TargetType.cs:
+#    5| [Class] TargetType
+#    7|   5: [Method] M2
+#    7|     -1: [TypeMention] Void
+#    8|     4: [BlockStmt] {...}
+#    9|       0: [LocalVariableDeclStmt] ... ...;
+#    9|         0: [LocalVariableDeclAndInitExpr] Random rand = ...
+#    9|           -1: [TypeMention] Random
+#    9|           0: [LocalVariableAccess] access to local variable rand
+#    9|           1: [ObjectCreation] object creation of type Random
+#    9|             0: [TypeMention] Random
+#   10|       1: [LocalVariableDeclStmt] ... ...;
+#   10|         0: [LocalVariableDeclAndInitExpr] Boolean condition = ...
+#   10|           -1: [TypeMention] bool
+#   10|           0: [LocalVariableAccess] access to local variable condition
+#   10|           1: [GTExpr] ... > ...
+#   10|             0: [MethodCall] call to method NextDouble
+#   10|               -1: [LocalVariableAccess] access to local variable rand
+#   10|             1: [DoubleLiteral] 0.5
+#   12|       2: [LocalVariableDeclStmt] ... ...;
+#   12|         0: [LocalVariableDeclAndInitExpr] Nullable<Int32> x = ...
+#   12|           -1: [TypeMention] int?
+#   12|             1: [TypeMention] int
+#   12|           0: [LocalVariableAccess] access to local variable x
+#   12|           1: [ConditionalExpr] ... ? ... : ...
+#   12|             0: [LocalVariableAccess] access to local variable condition
+#   13|             1: [CastExpr] (...) ...
+#   13|               1: [IntLiteral] 12
+#   14|             2: [NullLiteral] null
+#   16|       3: [LocalVariableDeclStmt] ... ...;
+#   16|         0: [LocalVariableDeclAndInitExpr] IEnumerable<Int32> xs = ...
+#   16|           -1: [TypeMention] IEnumerable<Int32>
+#   16|             1: [TypeMention] int
+#   16|           0: [LocalVariableAccess] access to local variable xs
+#   16|           1: [ConditionalExpr] ... ? ... : ...
+#   16|             0: [IsExpr] ... is ...
+#   16|               0: [LocalVariableAccess] access to local variable x
+#   16|               1: [ConstantPatternExpr,NullLiteral] null
+#   17|             1: [ObjectCreation] object creation of type List<Int32>
+#   17|               -2: [TypeMention] List<Int32>
+#   17|                 1: [TypeMention] int
+#   17|               -1: [CollectionInitializer] { ..., ... }
+#   17|                 0: [ElementInitializer] call to method Add
+#   17|                   0: [IntLiteral] 0
+#   17|                 1: [ElementInitializer] call to method Add
+#   17|                   0: [IntLiteral] 1
+#   18|             2: [ArrayCreation] array creation of type Int32[]
+#   18|               -2: [TypeMention] Int32[]
+#   18|                 1: [TypeMention] int
+#   18|               -1: [ArrayInitializer] { ..., ... }
+#   18|                 0: [IntLiteral] 2
+#   18|                 1: [IntLiteral] 3
 TypeParameterNullability.cs:
 #    1| [Interface] I1
 #    3| [Class] A2

csharp/ql/test/library-tests/csharp9/TargetType.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public class TargetType
+{
+    public void M2()
+    {
+        var rand = new Random();
+        var condition = rand.NextDouble() > 0.5;
+
+        int? x = condition
+            ? 12
+            : null;
+
+        IEnumerable<int> xs = x is null
+            ? new List<int>() { 0, 1 }
+            : new int[] { 2, 3 };
+    }
+}

csharp/ql/test/library-tests/csharp9/TargetType.expected

@@ -0,0 +1,2 @@
+| TargetType.cs:12:18:14:18 | ... ? ... : ... | int? | int? | null |
+| TargetType.cs:16:31:18:32 | ... ? ... : ... | IEnumerable<Int32> | List<Int32> | Int32[] |

csharp/ql/test/library-tests/csharp9/TargetType.ql

@@ -0,0 +1,7 @@
+import csharp
+
+query predicate conditional(ConditionalExpr expr, string t, string t1, string t2) {
+  expr.getType().toStringWithTypes() = t and
+  expr.getThen().getType().toStringWithTypes() = t1 and
+  expr.getElse().getType().toStringWithTypes() = t2
+}