Add example of function scope pytest fixtures

Author: gjbex

source-code/testing/PyTest/Fixtures/README.md

@@ -4,6 +4,8 @@ A simple illustration of using fixtures in pytest.
 ## What is it?
 1. `test_data_structure.py`: creates a test and a module fixture, and
     defines three tests, one of which is intended to fail.
+1. `test_list.py`: creates a list and tests whether `pop` and `append` work,
+   illustrates the advantage of `function` scope fixtures.
 1. `test_wc.py`: creates a module fixture that will be torn down when
     the test is done.
 

source-code/testing/PyTest/Fixtures/test_list.py

@@ -0,0 +1,22 @@
+import pytest
+
+
+@pytest.fixture
+def non_empty_list():
+    return list(range(5))
+
+
+def test_pop(non_empty_list):
+    orig_len = len(non_empty_list)
+    assert non_empty_list[-1] == orig_len - 1
+    non_empty_list.pop()
+    assert len(non_empty_list) == orig_len - 1
+    assert non_empty_list[-1] == orig_len - 2
+
+
+def test_append(non_empty_list):
+    orig_len = len(non_empty_list)
+    assert non_empty_list[-1] == orig_len - 1
+    non_empty_list.append(orig_len)
+    assert len(non_empty_list) == orig_len + 1
+    assert non_empty_list[-1] == orig_len