move decompress_file to util/testing.py

Author: reidy-p

pandas/tests/series/test_io.py

@@ -139,24 +139,6 @@ def test_to_csv_path_is_none(self):
         csv_str = s.to_csv(path=None)
         assert isinstance(csv_str, str)
 
-    def decompress_file(self, src_path, compression):
-        if compression is None:
-            f = open(src_path, 'rb')
-        elif compression == 'gzip':
-            import gzip
-            f = gzip.open(src_path, 'rb')
-        elif compression == 'bz2':
-            import bz2
-            f = bz2.BZ2File(src_path, 'rb')
-        elif compression == 'xz':
-            lzma = compat.import_lzma()
-            f = lzma.LZMAFile(src_path, 'rb')
-        else:
-            msg = 'Unrecognized compression type: {}'.format(compression)
-            raise ValueError(msg)
-
-        return f
-
     @pytest.mark.parametrize('compression', [
         None,
         'gzip',
@@ -178,12 +160,12 @@ def test_to_csv_compression(self, compression):
             assert_series_equal(s, rs)
 
             # explicitly ensure file was compressed
-            f = self.decompress_file(filename, compression=compression)
+            f = tm.decompress_file(filename, compression=compression)
             text = f.read().decode('utf8')
             assert s.name in text
             f.close()
 
-            f = self.decompress_file(filename, compression=compression)
+            f = tm.decompress_file(filename, compression=compression)
             assert_series_equal(s, pd.read_csv(f, index_col=0, squeeze=True))
             f.close()
 

pandas/util/testing.py

@@ -161,6 +161,39 @@ def round_trip_localpath(writer, reader, path=None):
         obj = reader(LocalPath(path))
     return obj
 
+def decompress_file(path, compression):
+    """
+    Open a compressed file and return a file object
+
+    Parameters
+    ----------
+    path : str
+        The path where the file is read from
+
+    compression : {'gzip', 'bz2', 'xz', None}
+        Name of the decompression to use
+
+    Returns
+    -------
+    f : file object
+    """
+
+    if compression is None:
+        f = open(path, 'rb')
+    elif compression == 'gzip':
+        import gzip
+        f = gzip.open(path, 'rb')
+    elif compression == 'bz2':
+        import bz2
+        f = bz2.BZ2File(path, 'rb')
+    elif compression == 'xz':
+        lzma = compat.import_lzma()
+        f = lzma.LZMAFile(path, 'rb')
+    else:
+        msg = 'Unrecognized compression type: {}'.format(compression)
+        raise ValueError(msg)
+
+    return f
 
 def assert_almost_equal(left, right, check_exact=False,
                         check_dtype='equiv', check_less_precise=False,