BUG: Infer compression by default in read_fwf() (#22199)

Author: NasaGeek

pandas/io/parsers.py

@@ -427,7 +427,7 @@ def _read(filepath_or_buffer, kwds):
         encoding = re.sub('_', '-', encoding).lower()
         kwds['encoding'] = encoding
 
-    compression = kwds.get('compression')
+    compression = kwds.get('compression', 'infer')
     compression = _infer_compression(filepath_or_buffer, compression)
     filepath_or_buffer, _, compression, should_close = get_filepath_or_buffer(
         filepath_or_buffer, encoding, compression)

pandas/tests/io/parser/test_read_fwf.py

@@ -206,15 +206,17 @@ def test_fwf_compression(self):
         expected = read_fwf(StringIO(data), widths=widths, names=names)
         if compat.PY3:
             data = bytes(data, encoding='utf-8')
-        comps = [('gzip', gzip.GzipFile), ('bz2', bz2.BZ2File)]
-        for comp_name, compresser in comps:
-            with tm.ensure_clean() as path:
-                tmp = compresser(path, mode='wb')
-                tmp.write(data)
-                tmp.close()
-                result = read_fwf(path, widths=widths, names=names,
-                                  compression=comp_name)
-                tm.assert_frame_equal(result, expected)
+        comps = [('gzip', 'gz', gzip.GzipFile), ('bz2', 'bz2', bz2.BZ2File)]
+        for comp_name, extension, compresser in comps:
+            for kwargs in [
+                    {'compression': comp_name}, {'compression': 'infer'}, {}]:
+                with tm.ensure_clean(filename='tmp.%s' % extension) as path:
+                    tmp = compresser(path, mode='wb')
+                    tmp.write(data)
+                    tmp.close()
+                    result = read_fwf(path, widths=widths, names=names,
+                                      **kwargs)
+                    tm.assert_frame_equal(result, expected)
 
     def test_comment_fwf(self):
         data = """