Improve handling delisted tickers

test_yfinance.py

@@ -15,22 +15,52 @@
 
 import yfinance as yf
 import unittest
+import datetime
+
+session = None
+import requests_cache ; session = requests_cache.CachedSession("yfinance.cache", expire_after=24*60*60)
 
 symbols = ['MSFT', 'IWO', 'VFINX', '^GSPC', 'BTC-USD']
-tickers = [yf.Ticker(symbol) for symbol in symbols]
+tickers = [yf.Ticker(symbol, session=session) for symbol in symbols]
+delisted_symbols = ["BRK.B", "SDLP"]
+delisted_tickers = [yf.Ticker(symbol, session=session) for symbol in delisted_symbols]
 
 
 class TestTicker(unittest.TestCase):
+    def setUp(self):
+        d_today = datetime.date.today()
+        d_today -= datetime.timedelta(days=30)
+        self.start_d = datetime.date(d_today.year, d_today.month, 1)
+
     def test_info_history(self):
+        # always should have info and history for valid symbols
         for ticker in tickers:
-            # always should have info and history for valid symbols
             assert(ticker.info is not None and ticker.info != {})
-            history = ticker.history(period="max")
+            history = ticker.history(period="1mo")
             assert(history.empty is False and history is not None)
+        histories = yf.download(symbols, period="1mo", session=session)
+        assert(histories.empty is False and histories is not None)
 
-        histories = yf.download(symbols, period="1yr")
+        for ticker in tickers:
+            assert(ticker.info is not None and ticker.info != {})
+            history = ticker.history(start=self.start_d)
+            assert(history.empty is False and history is not None)
+        histories = yf.download(symbols, start=self.start_d, session=session)
         assert(histories.empty is False and histories is not None)
 
+    def test_info_history_nofail(self):
+        # should not throw Exception for delisted tickers, just print a message
+        for ticker in delisted_tickers:
+            history = ticker.history(period="1mo")
+        histories = yf.download(delisted_symbols, period="1mo", session=session)
+        histories = yf.download(delisted_symbols[0], period="1mo", session=session)
+        histories = yf.download(delisted_symbols[1], period="1mo")#, session=session)
+        for ticker in delisted_tickers:
+            history = ticker.history(start=self.start_d)
+        histories = yf.download(delisted_symbols, start=self.start_d, session=session)
+        histories = yf.download(delisted_symbols[0], start=self.start_d, session=session)
+        histories = yf.download(delisted_symbols[1], start=self.start_d, session=session)
+
     def test_attributes(self):
         for ticker in tickers:
             ticker.isin
@@ -58,6 +88,34 @@ def test_attributes(self):
             ticker.earnings_history
             ticker.earnings_dates
 
+    def test_attributes_nofail(self):
+        # should not throw Exception for delisted tickers, just print a message
+        for ticker in delisted_tickers:
+            ticker.isin
+            ticker.major_holders
+            ticker.institutional_holders
+            ticker.mutualfund_holders
+            ticker.dividends
+            ticker.splits
+            ticker.actions
+            ticker.info
+            ticker.calendar
+            ticker.recommendations
+            ticker.earnings
+            ticker.quarterly_earnings
+            ticker.financials
+            ticker.quarterly_financials
+            ticker.balance_sheet
+            ticker.quarterly_balance_sheet
+            ticker.cashflow
+            ticker.quarterly_cashflow
+            ticker.sustainability
+            ticker.options
+            ticker.news
+            ticker.shares
+            ticker.earnings_history
+            ticker.earnings_dates
+
     def test_holders(self):
         for ticker in tickers:
             assert(ticker.info is not None and ticker.info != {})

yfinance/base.py

@@ -349,11 +349,12 @@ def _get_ticker_tz(self, debug_mode, proxy, timeout):
         if tkr_tz is None:
             tkr_tz = self._fetch_ticker_tz(debug_mode, proxy, timeout)
 
-            try:
-                utils.cache_store_tkr_tz(self.ticker, tkr_tz)
-            except PermissionError:
-                # System probably read-only, so cannot cache
-                pass
+            if tkr_tz is not None:
+                try:
+                    utils.cache_store_tkr_tz(self.ticker, tkr_tz)
+                except PermissionError:
+                    # System probably read-only, so cannot cache
+                    pass
 
         self._tz = tkr_tz
         return tkr_tz
@@ -858,6 +859,10 @@ def get_isin(self, proxy=None):
         self.get_info(proxy=proxy)
         if "shortName" in self._info:
             q = self._info['shortName']
+        if q is None:
+            err_msg = "Cannot map to ISIN code, symbol may be delisted"
+            print('- %s: %s' % (self.ticker, err_msg))
+            return None
 
         url = 'https://markets.businessinsider.com/ajax/' \
               'SearchController_Suggest?max_results=25&query=%s' \
@@ -956,8 +961,10 @@ def get_earnings_dates(self, proxy=None):
                 dates = _pd.concat([dates, data], axis=0)
             page_offset += page_size
 
-        if dates is None:
-            raise Exception("No data found, symbol may be delisted")
+        if (dates is None) or dates.shape[0]==0:
+            err_msg = "No earnings dates found, symbol may be delisted"
+            print('- %s: %s' % (self.ticker, err_msg))
+            return None
         dates = dates.reset_index(drop=True)
 
         # Drop redundant columns