Default weekly report to monday

closes #8502

freqtrade/optimize/optimize_reports.py

@@ -273,7 +273,8 @@ def _get_resample_from_period(period: str) -> str:
     if period == 'day':
         return '1d'
     if period == 'week':
-        return '1w'
+        # Weekly defaulting to Monday.
+        return '1W-MON'
     if period == 'month':
         return '1M'
     raise ValueError(f"Period {period} is not supported.")

tests/optimize/test_optimize_reports.py

@@ -465,7 +465,7 @@ def test_generate_periodic_breakdown_stats(testdatadir):
 def test__get_resample_from_period():
 
     assert _get_resample_from_period('day') == '1d'
-    assert _get_resample_from_period('week') == '1w'
+    assert _get_resample_from_period('week') == '1W-MON'
     assert _get_resample_from_period('month') == '1M'
     with pytest.raises(ValueError, match=r"Period noooo is not supported."):
         _get_resample_from_period('noooo')