[F#]Coverage reporting from F# lambda expressions loses branch information

[SteveGilham]

Code under test

namespace ClassLibrary1

open System
open System.IO
open System.Linq

module CommandLine =
 let internal WriteColoured (writer:TextWriter) colour operation =
    let original = Console.ForegroundColor
    try
      Console.ForegroundColor <- colour
      operation writer
    finally
      Console.ForegroundColor <- original

 let Usage ((intro:string), (options:obj seq), (options2:obj seq)) =
    WriteColoured Console.Error ConsoleColor.Yellow (fun w ->  if options.Any() || options2.Any() then
                                                                  w.WriteLine intro
                                                               if options.Any() then
                                                                 w.WriteLine("options")
                                                               if options.Any() && options2.Any() then
                                                                 w.WriteLine "binder"
                                                               if options2.Any() then
                                                                 w.WriteLine("options2")
                                                               else if options.Any() then
                                                                   w.WriteLine "orbinder"
                                                                   w.WriteLine "tail")

driven by test code

        [Fact]
        public void Test1()
        {
            var l = new object[] { };
            var m = new object[] { l };
            ClassLibrary1.CommandLine.Usage("string", l, l);
            ClassLibrary1.CommandLine.Usage("string", m, m);
        }

run dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=opencover

The report to the console is | ClassLibrary1 | 100% | 92.9% | 100% | The XML report, however, contains no branch points.

[tonerdo]

Thanks for reporting this @SteveGilham. Quick question, is the branch information preserved in the json output format?

[SteveGilham]

Branches, but no lines, are present for class ClassLibrary1.CommandLine/Usage@17 (i.e. the lambda) in the Invoke method; the OpenCover format has the class, but with no methods.

In both cases lines that correspond to code in the lambda are reported as belonging to the containing method Usage

[MarcoRossignoli]

possible dup of https://github.com/tonerdo/coverlet/issues/343

[Bertk]

The issue might be out-dated because new releases are available.

Please reopen the issue if the bug still exists and can be reproduced with latest preview from coverlet nightly build.

see Consume nightly build