text: from bootcamp_module09.core.instructor_03 import count_substring  # noqa
  
  
  def test_count_substring_single():
      test_string = "CGCTAGCGT"
      test_substring = "TAG"
  
      expected_count = 1
      observed_count = count_substring(test_string, test_substring)
      assert expected_count == observed_count
  
  
  def test_count_substring_repeated():
      test_string = "AGCTAGCAGT"
      test_substring = "AGC"
  
      expected_count = 2
      observed_count = count_substring(test_string, test_substring)
      assert expected_count == observed_count
  
  
  def test_count_substring_none():
      test_string = "AGTCCCCTAGA"
      test_substring = "AAA"
  
      expected_count = 0
      observed_count = count_substring(test_string, test_substring)
      assert expected_count == observed_count
  