Clean Code: Python

Fix issues found by flake8-bugbear:

* Unused loop variables
* assert statements in non-test code
* mixing test code with production code
* mark one excessive test which takes ~10min to run
  as 'slow'

95_Weekday/python/test_weekday.py

@@ -0,0 +1,49 @@
+import datetime
+
+import pytest
+from weekday import calculate_day_of_week
+
+
+@pytest.mark.parametrize(
+    ("year", "month", "day"),
+    [
+        (yr, m, d)
+        for yr in range(1600, 2021)
+        for m in range(1, 12)
+        for d in range(1, 28)
+    ],
+)
+@pytest.mark.slow  # Those are 125,037 tests!
+def test_weekday_calc(year, month, day):
+    dt = datetime.date(year, month, day)
+    python_weekday = dt.weekday()  # Monday = 0, Sunday = 6
+
+    basic_weekday = calculate_day_of_week(year, month, day)  # Sunday = 1, Saturday = 7
+
+    if ((python_weekday + 2) % 7) != (basic_weekday % 7):
+        print(f"testing yr {year} month {month} day {day}")
+        print(f"python says {python_weekday}")
+        print(f"BASIC says {basic_weekday}")
+        assert False
+
+
+@pytest.mark.parametrize(
+    ("year", "month", "day"),
+    [
+        (yr, m, d)
+        for yr in range(2016, 2021)
+        for m in range(1, 12)
+        for d in range(1, 28)
+    ],
+)
+def test_weekday_calc_4_years(year, month, day):
+    dt = datetime.date(year, month, day)
+    python_weekday = dt.weekday()  # Monday = 0, Sunday = 6
+
+    basic_weekday = calculate_day_of_week(year, month, day)  # Sunday = 1, Saturday = 7
+
+    if ((python_weekday + 2) % 7) != (basic_weekday % 7):
+        print(f"testing yr {year} month {month} day {day}")
+        print(f"python says {python_weekday}")
+        print(f"BASIC says {basic_weekday}")
+        assert False