TST: fix testing for yahoo get_data_null_as_missing comparisons (#367)

* TST: fix testing for yahoo get_data_null_as_missing comparisons

xref #357

* Revert "CI: use latest pandas"

This reverts commit 3b8b11a.

.travis.yml

@@ -22,7 +22,7 @@ matrix:
       - PYTHON=3.6 PANDAS=0.19.2
   - dist: trusty
     env:
-      - PYTHON=3.6 PANDAS=LATEST
+      - PYTHON=3.6 PANDAS=0.20.2
   # In allow failures
   - dist: trusty
     env:
@@ -57,8 +57,6 @@ install:
       conda install numpy pytz python-dateutil;
       PRE_WHEELS="https://7933911d6844c6c53a7d-47bd50c35cd79bd838daf386af554a83.ssl.cf2.rackcdn.com";
       pip install --pre --upgrade --timeout=60 -f $PRE_WHEELS pandas;
-    elif [[ "$PANDAS" == "LATEST" ]]; then
-      conda install pandas
     else
       conda install pandas=$PANDAS;
     fi

pandas_datareader/tests/yahoo/test_yahoo.py

@@ -137,7 +137,13 @@ def test_get_data_null_as_missing_data(self, adj_pr):
         result = web.get_data_yahoo('SRCE', '20160626', '20160705',
                                     adjust_price=adj_pr)
         # sanity checking
-        assert result.dtypes.all() == np.floating
+        floats = ['Open', 'High', 'Low', 'Close']
+        if adj_pr:
+            floats.append('Adj_Ratio')
+        else:
+            floats.append('Adj Close')
+
+        assert result[floats].dtypes.all() == np.floating
 
     @skip_on_exception(RemoteDataError)
     def test_get_data_multiple_symbols_two_dates(self):