C#: Add more tests for cs/unchecked-return-value

Author: hvitved

csharp/ql/test/query-tests/API Abuse/UncheckedReturnValue/UncheckedReturnValue.cs

@@ -158,3 +158,23 @@ class C5 { }
     class C6 : C5 { }
     class C7 : C6 { }
 }
+
+class C5
+{
+    int M1() => 0;
+
+    void M2()
+    {
+        // GOOD
+        M1();
+        Action a = () => M1();
+        a = () => M1();
+        a = () => M1();
+        a = () => M1();
+        a = () => M1();
+        a = () => M1();
+        a = () => M1();
+        a = () => M1();
+        a = () => M1();
+    }
+}

csharp/ql/test/query-tests/API Abuse/UncheckedReturnValue/UncheckedReturnValue.expected

@@ -4,5 +4,6 @@
 | UncheckedReturnValue.cs:109:9:109:17 | call to method M1 | Result of call to 'M1' is ignored, but 90% of calls to this method have their result used. |
 | UncheckedReturnValue.cs:130:9:130:21 | call to method M2 | Result of call to 'M2' is ignored, but 90% of calls to this method have their result used. |
 | UncheckedReturnValue.cs:142:9:142:20 | call to method M3 | Result of call to 'M3' is ignored, but 90% of calls to this method have their result used. |
+| UncheckedReturnValue.cs:169:9:169:12 | call to method M1 | Result of call to 'M1' is ignored, but 90% of calls to this method have their result used. |
 | UncheckedReturnValueBad.cs:29:9:29:20 | call to method DoPrint | Result of call to 'DoPrint' is ignored, but 90% of calls to this method have their result used. |
 | UncheckedReturnValueBad.cs:36:13:36:40 | call to method Read | Result of call to 'Read' is ignored, but should always be checked. |