code: def test_get_pip_requirement_specifier():
      assert _get_pip_requirement_specifier("") == ""
      assert _get_pip_requirement_specifier(" ") == " "
      assert _get_pip_requirement_specifier("mlflow") == "mlflow"
      assert (
          _get_pip_requirement_specifier("mlflow==1.2.3")
          == "mlflow==1.2.3"
      )
      assert _get_pip_requirement_specifier("-r reqs.txt") == ""
      assert _get_pip_requirement_specifier("  -r reqs.txt") == " "
      assert (
          _get_pip_requirement_specifier("mlflow==1.2.3 --hash=foo")
          == "mlflow==1.2.3"
      )
      assert (
          _get_pip_requirement_specifier(
              "mlflow==1.2.3       --hash=foo"
          )
          == "mlflow==1.2.3      "
      )
      assert (
          _get_pip_requirement_specifier("mlflow-skinny==1.2 --foo=bar")
          == "mlflow-skinny==1.2"
      )
  
imports: import os
  import pytest
  import yaml
  from mlflow.exceptions import MlflowException
  from mlflow.utils.environment import _contains_mlflow_requirement, _deduplicate_requirements, _get_pip_deps, _get_pip_requirement_specifier, _is_mlflow_requirement, _is_pip_deps, _mlflow_conda_env, _overwrite_pip_deps, _parse_pip_requirements, _process_conda_env, _process_pip_requirements, _validate_env_arguments
  from tests.helper_functions import _mlflow_major_version_string
label_desc: Use image node_id 18 for calling a global function with example usage: test_get_pip_requirement_specifier() without return types