Hi, I need profile a slow my function test in suite test.
I used the suggestion of Bryan Stearns (https://selfamusementpark.com/profiling-a-slow-elixir-test)
but it does not work if I have variable or function outside the scope.
My hex version is

System.version
"1.6.4"

I tried iex -S mix profile.fprof --no-compile -e “Mix.Tasks.Test.run([])”, it work but the out is for all my test.
I need profile a single test , i tried iex -S mix profile.fprof --no-compile -e “Mix.Tasks.Test.run([only: "test/test_only_profile_trest.exs"])”

but the output is:

Erlang/OTP 20 [erts-9.3.1] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]

07:53:28.841 application=router module=Router function=start_link/1 [info]  started ... with opts [name: RouterGenServer]
07:53:28.841 application=router module=Router function=init/1 [debug] init Elixir.Router with args -->[]
Warmup...
warning: variable "x" is unused
  test/support/helper.exs:37

warning: variable "tdiff" is unused
  test/support/helper.exs:46

** (FunctionClauseError) no function clause matching in String.split/3    
    
    The following arguments were given to **String.split/3:**
    
        # 1
        {:only, "test/test_only_profile_trest.exs"}
    
        # 2
        ":"
    
        # 3
        []
    
    Attempted function clauses (showing 4 out of 4):
    
        def split(string, %Regex{} = pattern, options) when is_binary(string)
        def split(string, "", options) when is_binary(string)
        def split(string, pattern, []) when is_tuple(pattern) or is_binary(string)
        def split(string, pattern, options) when is_binary(string)
    
    (elixir) lib/string.ex:383: String.split/3
    (ex_unit) lib/ex_unit/filters.ex:17: ExUnit.Filters.parse_path/1
    (mix) lib/mix/tasks/test.ex:338: Mix.Tasks.Test.parse_files/2
    (mix) lib/mix/tasks/test.ex:260: Mix.Tasks.Test.run/1
    (mix) lib/mix/tasks/profile.fprof.ex:167: Mix.Tasks.Profile.Fprof.profile_and_analyse/2
    (mix) lib/mix/tasks/profile.fprof.ex:160: Mix.Tasks.Profile.Fprof.profile/2

My mistake where is?
The key “only” is true for task test.

Thanks in advance.
Paola.