title: WARNING: Failed to generate report: No data to report error in python using pytest module
body: <p>Sample.py code:</p>
  
  <pre><code>def sum(num1, num2):
      return num1 + num2
  
  
  def sum_only_positive(num1, num2):
      if num1 &gt; 0 and num2 &gt; 0:
          return num1 + num2
      else:
          return None
  
  test_sample.py code
  
  from . import sample
  
  import pytest
  
  def test_sum():
      assert sample.sum(5, 5) == 10
  
  def test_sum_positive_ok():
      assert sample.sum_only_positive(2, 2) == 4
  
  def test_sum_positive_fail():
      assert sample.sum_only_positive(-1, 2) is None
  </code></pre>
  
  <p>Coverage command : <code>pytest test_sample.py --cov=sample.py</code></p>
  
  <p>Error:</p>
  
  <pre><code>platform linux -- Python 3.5.2, pytest-5.4.1, py-1.8.1, pluggy-0.13.1
  rootdir: /home/apathapa/unit_test/warriorframework_py3
  plugins: cov-2.8.1
  collected 3 items                                                                                                                            
  
  test_sample.py ...                                                                                                                     [100%]Coverage.py warning: Module sample.py was never imported. (module-not-imported)
  Coverage.py warning: No data was collected. (no-data-collected)
  WARNING: Failed to generate report: No data to report.
  
  /home/apathapa/ut/lib/python3.5/site-packages/pytest_cov/plugin.py:254: PytestWarning: Failed to generate report: No data to report.
  
    self.cov_controller.finish()
  
  
  ----------- coverage: platform linux, python 3.5.2-final-0 -----------
  Name    Stmts   Miss  Cover
  ---------------------------
  
  
  ============================================================= 3 passed in 0.13s ==============================================================
  </code></pre>
  
  <p>Can anyone help me how to resolve this error?</p>