Add example of parameterized test

Author: gjbex

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

@@ -0,0 +1,11 @@
+# Parameterize
+
+pytest tests can be parameterized so that it can be run on a list of input
+arguments and expected output.
+
+
+## What is it?
+
+1. `fibonacci.py`: Python script that implements the Fibonacci function.
+1. `test_fib.py`: parameterized tests for the Fibonacci function.
+1. `pytest.ini`: pytest configuration file that defines a `slow` marker.

source-code/testing/PyTest/Parametrize/fibonacci.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+
+def fib(n):
+    if n < 0:
+        raise ValueError('fac argument must be positive')
+    elif n < 2:
+        return 1
+    else:
+        return fib(n - 1) + fib(n - 2)
+
+
+if __name__ == '__main__':
+    from argparse import ArgumentParser
+    arg_parser = ArgumentParser(description='compute fibonacci numbers')
+    arg_parser.add_argument('n', type=int, default=5,
+                            help='maximum argument')
+    options = arg_parser.parse_args()
+    for i in range(options.n + 1):
+        print(f'fib({i}) = {fib(i)}')

source-code/testing/PyTest/Parametrize/pytest.ini

@@ -0,0 +1,3 @@
+[pytest]
+markers =
+    slow: marks tests as slow (deselect with '-m "not slow"')

source-code/testing/PyTest/Parametrize/test_fib.py

@@ -0,0 +1,25 @@
+from fibonacci import fib
+
+import pytest
+
+@pytest.mark.parametrize("n, expected", [
+    (0, 1),
+    (1, 1),
+    (2, 2),
+    (5, 8),
+])
+def test_fib(n, expected):
+    assert fib(n) == expected
+
+@pytest.mark.slow
+@pytest.mark.parametrize("n, expected", [
+    (40, 165580141),
+    (41, 267914296),
+    (42, 433494437),
+])
+def test_fib_40(n, expected):
+    assert fib(n) == expected
+
+def test_fib_negative():
+    with pytest.raises(ValueError):
+        _ = fib(-1)    

source-code/testing/PyTest/README.md

@@ -8,3 +8,4 @@ module provided by the Python standard library.
 1. `Fixtures`: illustrates using fixtures with pytest.
 1. `CustomMarkers`: illustrates using custom markers with pytest to
    selectively run tests.
+1. `Parametrize`: illustrates using parameterized tests.