From a5a432966949ad32a3edfe75ecbace091b04633a Mon Sep 17 00:00:00 2001
From: Tamas Vajk <tamasvajk@github.com>
Date: Fri, 6 Nov 2020 10:37:38 +0100
Subject: [PATCH] C#: Add tests for covariant return types

---
 .../test/library-tests/csharp9/CovariantReturn.cs |  9 +++++++++
 .../test/library-tests/csharp9/PrintAst.expected  | 15 +++++++++++++++
 .../csharp9/covariantReturn.expected              |  1 +
 .../test/library-tests/csharp9/covariantReturn.ql |  8 ++++++++
 4 files changed, 33 insertions(+)
 create mode 100644 csharp/ql/test/library-tests/csharp9/CovariantReturn.cs
 create mode 100644 csharp/ql/test/library-tests/csharp9/covariantReturn.expected
 create mode 100644 csharp/ql/test/library-tests/csharp9/covariantReturn.ql

diff --git a/csharp/ql/test/library-tests/csharp9/CovariantReturn.cs b/csharp/ql/test/library-tests/csharp9/CovariantReturn.cs
new file mode 100644
index 00000000000..ac39aae893d
--- /dev/null
+++ b/csharp/ql/test/library-tests/csharp9/CovariantReturn.cs
@@ -0,0 +1,9 @@
+class A
+{
+    public virtual A M1() { throw null; }
+}
+
+class B : A
+{
+    public override B M1() { throw null; }
+}
\ No newline at end of file
diff --git a/csharp/ql/test/library-tests/csharp9/PrintAst.expected b/csharp/ql/test/library-tests/csharp9/PrintAst.expected
index 56299fbdc68..6da09ceb287 100644
--- a/csharp/ql/test/library-tests/csharp9/PrintAst.expected
+++ b/csharp/ql/test/library-tests/csharp9/PrintAst.expected
@@ -117,6 +117,21 @@ BinaryPattern.cs:
 #   19|           1: [SwitchCaseExpr] ... => ...
 #   19|             0: [DiscardPatternExpr] _
 #   19|             2: [StringLiteral] "other"
+CovariantReturn.cs:
+#    1| [Class] A
+#    3|   5: [Method] M1
+#    3|     -1: [TypeMention] A
+#    3|     4: [BlockStmt] {...}
+#    3|       0: [ThrowStmt] throw ...;
+#    3|         0: [NullLiteral] null
+#    6| [Class] B
+#-----|   3: (Base types)
+#    6|     0: [TypeMention] A
+#    8|   5: [Method] M1
+#    8|     -1: [TypeMention] B
+#    8|     4: [BlockStmt] {...}
+#    8|       0: [ThrowStmt] throw ...;
+#    8|         0: [NullLiteral] null
 Discard.cs:
 #    3| [Class] Discard
 #    5|   5: [Method] M1
diff --git a/csharp/ql/test/library-tests/csharp9/covariantReturn.expected b/csharp/ql/test/library-tests/csharp9/covariantReturn.expected
new file mode 100644
index 00000000000..789c8c7caaa
--- /dev/null
+++ b/csharp/ql/test/library-tests/csharp9/covariantReturn.expected
@@ -0,0 +1 @@
+| A.M1 | A | B.M1 | B |
diff --git a/csharp/ql/test/library-tests/csharp9/covariantReturn.ql b/csharp/ql/test/library-tests/csharp9/covariantReturn.ql
new file mode 100644
index 00000000000..f4958cbba31
--- /dev/null
+++ b/csharp/ql/test/library-tests/csharp9/covariantReturn.ql
@@ -0,0 +1,8 @@
+import csharp
+
+from Method m, Method overrider
+where
+  m.getAnOverrider() = overrider and
+  m.getFile().getStem() = "CovariantReturn"
+select m.getQualifiedName(), m.getReturnType().toString(), overrider.getQualifiedName(),
+  overrider.getReturnType().toString()