Nbench: dotnet-nbench can accidentally try to execute [assembly-name].deps.json instead of the assembly

Is there a workaround/alternative for now?

I tried changing the project target but realized the issue was really with the CLI. I got it working by:
1) changing the version of the CLI for that project by adding a global.json (ref: https://markheath.net/post/switching-between-netcore-sdk-versions )

2) i then had an error about not having 2.1 for a framework that required adding this to the csproj file in the PropertyGroup:
2.1.6

3) Then had error about packages restored with different runtime than build/publish. Fix for that was just to run "dotnet restore" from the cli again.

After that, i was able to run "dotnet nbench" against that project fine.

Thanks for posting the detailed workaround! @izavala and I are looking at doing another big usability overhaul for NBench 2.0 and this will be on our list for that.

Just in case someone runs into this, but like me can't fiddle with the target frameworks or global.json, another work-around is to use the undocumented --fx-version {version} flag with dotnet nbench, for example:

fxversion=$(dotnet --list-runtimes | \
    grep Microsoft.NETCore.App | \
    awk '{ print $2 }' | \
    tail -1)

dotnet nbench --fx-version $fxversion

Or:

$fxversion = dotnet --list-runtimes | `
    select-string "Microsoft.NETCore.App" | `
    select-object -last 1 | `
    foreach-object { $data = $_ -split " "; $data[1] }

dotnet nbench --fx-version $fxversion

The reason the command fails without this is that the runner formats a dotnet exec command with the fxVersion variable, and when it's empty, this results in --fx-version --depsfile "Foo.deps.json". This in turn is parsed by dotnet exec as if --depsfile were the value for the --fx-version flag, and the following Foo.deps.json is interpreted as the assembly file to run.

The offending line: https://github.com/petabridge/NBench/blob/557f2fbca250a4a45636f5e4b41b58b8440b33f2/src/NBench.Runner.DotNetCli/Program.cs#L284

This patch should fix it but I don't have time to do proper testing and/or a pull request right now:

diff --git a/src/NBench.Runner.DotNetCli/Program.cs b/src/NBench.Runner.DotNetCli/Program.cs
index c45b32e..417319c 100644
--- a/src/NBench.Runner.DotNetCli/Program.cs
+++ b/src/NBench.Runner.DotNetCli/Program.cs
@@ -281,7 +281,10 @@ namespace NBench.Runner.DotNetCli
             var depsFile = targetFileNameWithoutExtension + ".deps.json";
             var runtimeConfigJson = targetFileNameWithoutExtension + ".runtimeconfig.json";

-            var args = $@"exec --fx-version {fxVersion} --depsfile ""{depsFile}"" ";
+            var args = $@"exec --depsfile ""{depsFile}"" ";
+
+            if (!string.IsNullOrWhiteSpace(fxVersion))
+                args += $"--fx-version {fxVersion} ";

             if (File.Exists(Path.Combine(workingDirectory, runtimeConfigJson)))
                 args += $@"--runtimeconfig ""{runtimeConfigJson}"" ";

Resolved via NBench 2.0.0 https://github.com/petabridge/NBench/releases/tag/2.0.0 - no more dotnet nbench.