Using fprof with unit test - getting FunctionClauseError

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.

You need to specify the list of arguments as if you were giving it at the command line:

Mix.Tasks.Test.run(["--only", "test/test_only_profile_trest.exs"])

Aside of that, --only filters based on @tags, you probably want to pass only the file to run tests from:

Mix.Tasks.Test.run(["test/test_only_profile_trest.exs"])

Finally, I do think you have a typo in the filename :wink:

1 Like

Thanks Nobbz,
but not work

  • test 1:

iex -S mix profile.fprof --no-compile -e "Mix.Tasks.Test.run([“test/router_only_profile_test.exs”])"

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

08:43:52.041 application=router module=Router function=start_link/1 [info]  started ... with opts [name: RouterGenServer]
08:43:52.041 application=router module=Router function=init/1 [debug] init Elixir.Router with args -->[]
warning: variable "test" does not exist and is being expanded to "test()", please use parentheses to remove the ambiguity or change the variable name
  nofile:1

** (CompileError) nofile:1: undefined function test/0
    (stdlib) lists.erl:1354: :lists.mapfoldl/3

test 2:

iex -S mix profile.fprof --no-compile -e "Mix.Tasks.Test.run([“only”, “test/router_only_profile_test.exs”])"

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

08:44:12.995 application=router module=Router function=start_link/1 [info]  started ... with opts [name: RouterGenServer]
08:44:12.995 application=router module=Router function=init/1 [debug] init Elixir.Router with args -->[]
warning: variable "only" does not exist and is being expanded to "only()", please use parentheses to remove the ambiguity or change the variable name
  nofile:1

** (CompileError) nofile:1: undefined function only/0
    (elixir) src/elixir_fn.erl:21: anonymous fn/3 in :elixir_fn.expand/3

I removed my typing error :face_with_hand_over_mouth:.
Paola.

I’m not sure how exactly you write the command into the terminal.

Therefore please try these exact commands (copy and paste) and then show us the full transcript when they fail and properly wrap everything into a codeblock, not only the output, but also the command.

iex -S mix profile.fprof --no-compile -e 'Mix.Tasks.Test.run(["test/router_only_profile_test.exs"])'
iex -S mix profile.fprof --no-compile -e 'Mix.Tasks.Test.run(["--only", "test/router_only_profile_test.exs"])'
1 Like

Thank you very much for your help, the error was double quotes after -e.
Now work.
Thank.
Paola.