C#: Add test case for missing log message sinks with ambiguous types

csharp/ql/test/library-tests/standalone/externalLocationSink/externalLocationSink.expected

@@ -0,0 +1,6 @@
+#select
+compilationErrors
+| standalone.cs:16:12:16:18 | CS0104: 'ILogger' is an ambiguous reference between 'A.ILogger' and 'B.ILogger' |
+methodCalls
+| standalone.cs:20:9:20:21 | call to method  |
+| standalone.cs:25:9:25:33 | call to method  |

csharp/ql/test/library-tests/standalone/externalLocationSink/externalLocationSink.ql

@@ -0,0 +1,10 @@
+import semmle.code.csharp.security.dataflow.flowsinks.ExternalLocationSink
+import semmle.code.csharp.commons.Diagnostics
+
+from ExternalLocationSink sink
+where sink.getLocation().getFile().fromSource()
+select sink, sink.getExpr()
+
+query predicate compilationErrors(CompilerError e) { any() }
+
+query predicate methodCalls(MethodCall m) { any() }

csharp/ql/test/library-tests/standalone/externalLocationSink/options

@@ -0,0 +1 @@
+semmle-extractor-options: --standalone

csharp/ql/test/library-tests/standalone/externalLocationSink/standalone.cs

@@ -0,0 +1,27 @@
+using A;
+using B;
+
+namespace A
+{
+    public interface ILogger { }
+}
+
+namespace B
+{
+    public interface ILogger { }
+}
+
+public class C
+{
+    public ILogger logger;
+
+    private void M(string s)
+    {
+        logger.Log(s);
+    }
+
+    private static void Main()
+    {
+        new C().logger.Log("abc");
+    }
+}