Fix: Restore dev branch regression with Ticker.history()

tests/test_ticker.py

@@ -8,6 +8,8 @@
    python -m unittest tests.ticker.TestTicker
 
 """
+from datetime import datetime, timedelta
+
 import pandas as pd
 
 from tests.context import yfinance as yf
@@ -133,8 +135,55 @@ def test_invalid_period(self):
         with self.assertRaises(YFInvalidPeriodError):
             dat.history(period="2wks", interval="1d", raise_errors=True)
         with self.assertRaises(YFInvalidPeriodError):
-            dat.history(period="2mo", interval="1d", raise_errors=True)
+            dat.history(period="2mos", interval="1d", raise_errors=True)
+
+    def test_valid_custom_periods(self):
+        valid_periods = [
+            # Yahoo provided periods
+            ("1d", "1m"), ("5d", "15m"), ("1mo", "1d"), ("3mo", "1wk"),
+            ("6mo", "1d"), ("1y", "1mo"), ("5y", "1wk"), ("max", "1mo"),
+
+            # Custom periods
+            ("2d", "30m"), ("10mo", "1d"), ("1y", "1d"), ("3y", "1d"),
+            ("2wk", "15m"), ("6mo", "5d"), ("10y", "1wk")
+        ]
+
+        tkr = "AAPL"
+        dat = yf.Ticker(tkr, session=self.session)
 
+        for period, interval in valid_periods:
+            with self.subTest(period=period, interval=interval):
+                df = dat.history(period=period, interval=interval, raise_errors=True)
+                self.assertIsInstance(df, pd.DataFrame)
+                self.assertFalse(df.empty, f"No data returned for period={period}, interval={interval}")
+                self.assertIn("Close", df.columns, f"'Close' column missing for period={period}, interval={interval}")
+
+                # Validate date range
+                now = datetime.now()
+                if period != "max":  # Difficult to assert for "max", therefore we skip
+                    if period.endswith("d"):
+                        days = int(period[:-1])
+                        expected_start = now - timedelta(days=days)
+                    elif period.endswith("mo"):
+                        months = int(period[:-2])
+                        expected_start = now - timedelta(days=30 * months)
+                    elif period.endswith("y"):
+                        years = int(period[:-1])
+                        expected_start = now - timedelta(days=365 * years)
+                    elif period.endswith("wk"):
+                        weeks = int(period[:-2])
+                        expected_start = now - timedelta(weeks=weeks)
+                    else:
+                        continue
+
+                    actual_start = df.index[0].to_pydatetime().replace(tzinfo=None)
+                    expected_start = expected_start.replace(hour=0, minute=0, second=0, microsecond=0)
+
+                    # leeway added because of weekends
+                    self.assertGreaterEqual(actual_start, expected_start - timedelta(days=7),
+                                            f"Start date {actual_start} out of range for period={period}")
+                    self.assertLessEqual(df.index[-1].to_pydatetime().replace(tzinfo=None), now,
+                                         f"End date {df.index[-1]} out of range for period={period}")
 
     def test_prices_missing(self):
         # this test will need to be updated every time someone wants to run a test

tests/test_utils.py

@@ -21,6 +21,8 @@
 import tempfile
 import os
 
+from yfinance.utils import is_valid_period_format
+
 
 class TestCache(unittest.TestCase):
     @classmethod
@@ -105,11 +107,32 @@ def test_mixed_timezones_to_datetime(self):
             i += 1
 
 
+class TestUtils(unittest.TestCase):
+    def test_is_valid_period_format_valid(self):
+        self.assertTrue(is_valid_period_format("1d"))
+        self.assertTrue(is_valid_period_format("5wk"))
+        self.assertTrue(is_valid_period_format("12mo"))
+        self.assertTrue(is_valid_period_format("2y"))
+
+    def test_is_valid_period_format_invalid(self):
+        self.assertFalse(is_valid_period_format("1m"))    # Incorrect suffix
+        self.assertFalse(is_valid_period_format("2wks"))  # Incorrect suffix
+        self.assertFalse(is_valid_period_format("10"))    # Missing suffix
+        self.assertFalse(is_valid_period_format("abc"))   # Invalid string
+        self.assertFalse(is_valid_period_format(""))      # Empty string
+
+    def test_is_valid_period_format_edge_cases(self):
+        self.assertFalse(is_valid_period_format(None))    # None input
+        self.assertFalse(is_valid_period_format("0d"))    # Zero is invalid
+        self.assertTrue(is_valid_period_format("999mo"))  # Large number valid
+
+
 def suite():
     ts: TestSuite = unittest.TestSuite()
     ts.addTest(TestCache('Test cache'))
     ts.addTest(TestCacheNoPermission('Test cache no permission'))
     ts.addTest(TestPandas("Test pandas"))
+    ts.addTest(TestUtils("Test utils"))
     return ts
 
 

yfinance/exceptions.py

@@ -44,7 +44,8 @@ def __init__(self, ticker, invalid_period, valid_ranges):
         self.ticker = ticker
         self.invalid_period = invalid_period
         self.valid_ranges = valid_ranges
-        super().__init__(f"{self.ticker}: Period '{invalid_period}' is invalid, must be one of {valid_ranges}")
+        super().__init__(f"{self.ticker}: Period '{invalid_period}' is invalid, "
+                         f"must be of the format {valid_ranges}, etc.")
 
 
 class YFRateLimitError(YFException):

yfinance/scrapers/history.py

@@ -105,11 +105,6 @@ def history(self, period="1mo", interval="1d",
                 period_user = period
                 period = None
             interval = '1d'
-        else:
-            end = utils._parse_user_dt(end, self.tz)
-            start = _datetime.date.fromordinal(end)
-            start -= utils._interval_to_timedelta(period)
-            start -= _datetime.timedelta(days=4)
 
         start_user = start
         end_user = end
@@ -237,10 +232,9 @@ def history(self, period="1mo", interval="1d",
         elif "chart" not in data or data["chart"]["result"] is None or not data["chart"]["result"] or not data["chart"]["result"][0]["indicators"]["quote"][0]:
             _exception = YFPricesMissingError(self.ticker, _price_data_debug)
             fail = True
-        elif period is not None and period not in self._history_metadata["validRanges"]:
-            # even if timestamp is in the data, the data doesn't encompass the period requested
-            # User provided a bad period. The minimum should be '1d', but sometimes Yahoo accepts '1h'.
-            _exception = YFInvalidPeriodError(self.ticker, period, self._history_metadata['validRanges'])
+        elif period and period not in self._history_metadata['validRanges'] and not utils.is_valid_period_format(period):
+            # User provided a bad period
+            _exception = YFInvalidPeriodError(self.ticker, period, ", ".join(self._history_metadata['validRanges']))
             fail = True
 
         if fail:
@@ -255,6 +249,13 @@ def history(self, period="1mo", interval="1d",
                 self._reconstruct_start_interval = None
             return utils.empty_df()
 
+        # Process custom periods
+        if period and period not in self._history_metadata.get("validRanges", []):
+            end = int(_time.time())
+            start = _datetime.date.fromtimestamp(end)
+            start -= utils._interval_to_timedelta(period)
+            start -= _datetime.timedelta(days=4)
+
         # parse quotes
         quotes = utils.parse_quotes(data["chart"]["result"][0])
         # Yahoo bug fix - it often appends latest price even if after end date

yfinance/utils.py

@@ -23,6 +23,7 @@
 
 import datetime as _datetime
 import logging
+import re
 import re as _re
 import sys as _sys
 import threading
@@ -431,7 +432,7 @@ def _parse_user_dt(dt, exchange_tz):
 def _interval_to_timedelta(interval):
     if interval[-1] == "d":
         return relativedelta(days=int(interval[:-1]))
-    elif interval[-2:] == "wk": 
+    elif interval[-2:] == "wk":
         return relativedelta(weeks=int(interval[:-2]))
     elif interval[-2:] == "mo":
         return relativedelta(months=int(interval[:-2]))
@@ -441,6 +442,16 @@ def _interval_to_timedelta(interval):
         return _pd.Timedelta(interval)
 
 
+def is_valid_period_format(period):
+    """Check if the provided period has a valid format."""
+    if period is None:
+        return False
+
+    # Regex pattern to match valid period formats like '1d', '2wk', '3mo', '1y'
+    valid_pattern = r"^[1-9]\d*(d|wk|mo|y)$"
+    return bool(re.match(valid_pattern, period))
+
+
 def auto_adjust(data):
     col_order = data.columns
     df = data.copy()