diff --git a/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.cs b/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.cs
new file mode 100644
index 00000000000..2a4ea1fdb61
--- /dev/null
+++ b/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.cs
@@ -0,0 +1,12 @@
+using System;
+
+public class SupportExternalSources
+{
+    public void M1()
+    {
+        var l1 = Console.ReadLine(); // Known source.
+        var l2 = Console.ReadLine(); // Known source.
+        Console.SetError(Console.Out);
+        var x = Console.Read(); // Know source.
+    }
+}
diff --git a/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.expected b/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.expected
new file mode 100644
index 00000000000..0f125b04b94
--- /dev/null
+++ b/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.expected
@@ -0,0 +1,2 @@
+| System.Console.dll#System#Console.ReadLine() | 2 |
+| System.Console.dll#System#Console.Read() | 1 |
diff --git a/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.qlref b/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.qlref
new file mode 100644
index 00000000000..c6819c7775f
--- /dev/null
+++ b/csharp/ql/test/query-tests/Telemetry/SupportedExternalSources/SupportedExternalSources.qlref
@@ -0,0 +1 @@
+Telemetry/SupportedExternalSources.ql