econdb - black restyle, and add test

Author: StochasticDoge

pandas_datareader/econdb.py

@@ -21,20 +21,20 @@ def url(self):
         )
 
     def read(self):
-        """ read one data from specified URL """
-        params = dict(s.split('=') for s in self.symbols.split('&'))
-        if 'from' in params:
-            self.start = pd.to_datetime(params['from'], format='%Y-%m-%d')
-        if 'to' in params:
-            self.end = pd.to_datetime(params['to'], format='%Y-%m-%d')
+        """read one data from specified URL"""
+        params = dict(s.split("=") for s in self.symbols.split("&"))
+        if "from" in params:
+            self.start = pd.to_datetime(params["from"], format="%Y-%m-%d")
+        if "to" in params:
+            self.end = pd.to_datetime(params["to"], format="%Y-%m-%d")
 
         results = self.session.get(self.url).json()["results"]
         df = pd.DataFrame({"dates": []}).set_index("dates")
 
         if self._show == "labels":
 
             def show_func(x):
-                return x[x.find(":") + 1:]
+                return x[x.find(":") + 1 :]
 
         elif self._show == "codes":
 

pandas_datareader/tests/test_econdb.py

@@ -1,14 +1,28 @@
 import numpy as np
 import pandas as pd
-from pandas import testing as tm
 import pytest
+from pandas import testing as tm
 
 from pandas_datareader import data as web
 
 pytestmark = pytest.mark.stable
 
 
 class TestEcondb(object):
+    def test_infer_start_end_from_symbols(self):
+        df = web.DataReader(
+            (
+                "dataset=NAMQ_10_GDP&v=Geopolitical entity (reporting)"
+                "&h=TIME&from=2010-02-01&to=2018-10-01&GEO=[AL,AT,BE,BA,"
+                "BG,HR,CY,CZ,DK,EE,EA19,FI,FR,DE,EL,HU,IS,IE,IT,XK,LV,LT,"
+                "LU,MT,ME,NL,MK,NO,PL,PT,RO,RS,SK,SI,ES,SE,CH,TR,UK]"
+                "&NA_ITEM=[B1GQ]&S_ADJ=[SCA]&UNIT=[CLV10_MNAC]"
+            ),
+            "econdb",
+        )
+        assert df.index[0].year == 2010
+        assert df.index[-1].year == 2018
+
     def test_get_cdh_e_fos(self):
         # EUROSTAT
         # Employed doctorate holders in non managerial and non professional
@@ -79,7 +93,6 @@ def test_bls(self):
         assert df.loc["2010-05-01"][0] == 217.3
 
     def test_australia_gdp(self):
-
         df = web.DataReader(
             "dataset=ABS_GDP&to=2019-09-01&from=1959-09-01&h=TIME&v=Indicator", "econdb"
         )