code: def test_selection_rate_non_numeric():
      a = "a"
      b = "b"
      y_true = [a, b, a, b, a, b, a, b]
      y_pred = [a, a, a, b, b, b, a, a]
  
      result = metrics.selection_rate(y_true, y_pred, pos_label=b)
  
      assert result == 0.375
  
imports: import pytest
  import fairlearn.metrics
  from fairlearn.metrics._base_metrics import _EMPTY_INPUT_PREDICTIONS_ERROR_MESSAGE
label_desc: Use image node_id 5 for calling a global function with example usage: test_selection_rate_non_numeric() without return types