expand test cases

Author: chris-b1

doc/source/whatsnew/v0.20.0.txt

@@ -461,13 +461,20 @@ New Behavior:
 
 .. code-block:: ipython
 
-   df = pd.DataFrame({'unparsed_date': ['2014-01-01', '2014-01-01']})
-   df.to_hdf('store.h5', 'key', format='table', data_columns=True)
-   ts = pd.Timestamp('2014-01-01')
-   try:
-       pd.read_hdf('store.h5', 'key', where='unparsed_date > ts')
-   except TypeError:
-       print("TypeError raised")
+   In [15]: df = pd.DataFrame({'unparsed_date': ['2014-01-01', '2014-01-01']})
+
+   In [16]: df.dtypes
+   Out[16]: 
+   unparsed_date    object
+   dtype: object
+
+   In [17]: df.to_hdf('store.h5', 'key', format='table', data_columns=True)
+
+   In [18]: ts = pd.Timestamp('2014-01-01')
+
+   In [19]: pd.read_hdf('store.h5', 'key', where='unparsed_date > ts')
+   TypeError: Cannot compare 2014-01-01 00:00:00 of
+   type <class 'pandas.tslib.Timestamp'> to string column
 
 
 .. _whatsnew_0200.api:

pandas/tests/io/test_pytables.py

@@ -5080,12 +5080,13 @@ def test_query_long_float_literal(self):
             expected = df.loc[[1], :]
             tm.assert_frame_equal(expected, result)
 
-    def test_query_compare_string_column(self):
+    def test_query_compare_column_type(self):
         # GH 15492
         df = pd.DataFrame({'date': ['2014-01-01', '2014-01-02'],
                            'real_date': date_range('2014-01-01', periods=2),
-                           'values': [1, 2]},
-                          columns=['date', 'real_date', 'values'])
+                           'float': [1.1, 1.2],
+                           'int': [1, 2]},
+                          columns=['date', 'real_date', 'float', 'int'])
 
         with ensure_clean_store(self.path) as store:
             store.append('test', df, format='table', data_columns=True)
@@ -5095,12 +5096,34 @@ def test_query_compare_string_column(self):
             expected = df.loc[[1], :]
             tm.assert_frame_equal(expected, result)
 
-            for v in [2.1, True, pd.Timestamp('2014-01-01')]:
-                for op in ['<', '>', '==']:
+            for op in ['<', '>', '==']:
+                # non strings to string column always fail
+                for v in [2.1, True, pd.Timestamp('2014-01-01'),
+                          pd.Timedelta(1, 's')]:
                     query = 'date {op} v'.format(op=op)
                     with tm.assertRaises(TypeError):
                         result = store.select('test', where=query)
 
+                # strings to other columns must be convertible to type
+                v = 'a'
+                for col in ['int', 'float', 'real_date']:
+                    query = '{col} {op} v'.format(op=op, col=col)
+                    with tm.assertRaises(ValueError):
+                        result = store.select('test', where=query)
+
+                for v, col in zip(['1', '1.1', '2014-01-01'],
+                                  ['int', 'float', 'real_date']):
+                    query = '{col} {op} v'.format(op=op, col=col)
+                    result = store.select('test', where=query)
+
+                    if op == '==':
+                        expected = df.loc[[0], :]
+                    elif op == '>':
+                        expected = df.loc[[1], :]
+                    else:
+                        expected = df.loc[[], :]
+                    tm.assert_frame_equal(expected, result)
+
 
 class TestHDFComplexValues(Base):
     # GH10447