add a test

Author: Timur Kelman

Tests/CSharp/MemberTests/MemberTests.cs

@@ -4049,4 +4049,52 @@ public static int StaticTestProperty
     }
 }");
     }
+
+    [Fact]
+    public async Task TestMissingByRefArgumentWithNoExplicitDefaultValueAsync()
+    {
+        await TestConversionVisualBasicToCSharpAsync(
+            @"Imports System.Runtime.InteropServices
+
+Class MissingByRefArgumentWithNoExplicitDefaultValue
+    Sub S()
+        ByRefNoDefault()
+        OptionalByRefNoDefault()
+        OptionalByRefWithDefault()
+    End Sub
+
+    Private Sub ByRefNoDefault(ByRef str1 As String) : End Sub
+    Private Sub OptionalByRefNoDefault(<[Optional]> ByRef str2 As String) : End Sub
+    Private Sub OptionalByRefWithDefault(<[Optional], DefaultParameterValue(""a"")> ByRef str3 As String) : End Sub
+End Class", @"using System.Runtime.InteropServices;
+
+internal partial class MissingByRefArgumentWithNoExplicitDefaultValue
+{
+    public void S()
+    {
+        ByRefNoDefault();
+        string argstr2 = default;
+        OptionalByRefNoDefault(str2: ref argstr2);
+        string argstr3 = ""a"";
+        OptionalByRefWithDefault(str3: ref argstr3);
+    }
+
+    private void ByRefNoDefault(ref string str1)
+    {
+    }
+    private void OptionalByRefNoDefault([Optional] ref string str2)
+    {
+    }
+    private void OptionalByRefWithDefault([Optional][DefaultParameterValue(""a"")] ref string str3)
+    {
+    }
+}
+3 source compilation errors:
+BC30455: Argument not specified for parameter 'str1' of 'Private Sub ByRefNoDefault(ByRef str1 As String)'.
+BC30455: Argument not specified for parameter 'str2' of 'Private Sub OptionalByRefNoDefault(ByRef str2 As String)'.
+BC30455: Argument not specified for parameter 'str3' of 'Private Sub OptionalByRefWithDefault(ByRef str3 As String)'.
+1 target compilation errors:
+CS7036: There is no argument given that corresponds to the required formal parameter 'str1' of 'MissingByRefArgumentWithNoExplicitDefaultValue.ByRefNoDefault(ref string)'
+");
+    }
 }