REF/TST: Add more pytest idiom to test_read_fwf.py (pandas-dev#24361)

Also refactors out a compression writing utility
function originally just for test_compression
in the same directory.

Author: gfyoung

pandas/tests/io/parser/test_compression.py

@@ -5,73 +5,15 @@
 of the parsers defined in parsers.py
 """
 
-import bz2
-import gzip
 import os
 import zipfile
 
 import pytest
 
-import pandas.compat as compat
-
 import pandas as pd
 import pandas.util.testing as tm
 
 
-def lzma_file():
-    """
-    Try to load the `LZMAFile` class from `backports.lzma`.
-
-    Returns
-    -------
-    klass : type or None
-    """
-    try:
-        lzma = compat.import_lzma()
-    except ImportError:
-        lzma = None
-
-    return getattr(lzma, "LZMAFile", None)
-
-
-def write_to_compressed(compress_type, path, data, dest="test"):
-    """
-    Write data to a compressed file.
-
-    Parameters
-    ----------
-    compress_type : type
-        The compression type (or class) to use.
-    path : str
-        The file path to write the data.
-    data : str
-        The data to write.
-    dest : str, default "test"
-        The destination file (for ZIP only)
-    """
-    # compression --> compression_method
-    compression_mappings = {
-        "zip": zipfile.ZipFile,
-        "gzip": gzip.GzipFile,
-        "bz2": bz2.BZ2File,
-        "xz": lzma_file(),
-    }
-
-    compress_method = compression_mappings[compress_type]
-
-    if compress_type == "zip":
-        mode = "w"
-        args = (dest, data)
-        method = "writestr"
-    else:
-        mode = "wb"
-        args = (data,)
-        method = "write"
-
-    with compress_method(path, mode=mode) as f:
-        getattr(f, method)(*args)
-
-
 @pytest.fixture(params=[True, False])
 def buffer(request):
     return request.param
@@ -154,7 +96,7 @@ def test_compression(parser_and_data, compression_only, buffer, filename):
                     "buffer of compressed data.")
 
     with tm.ensure_clean(filename=filename) as path:
-        write_to_compressed(compress_type, path, data)
+        tm.write_to_compressed(compress_type, path, data)
         compression = "infer" if filename else compress_type
 
         if buffer: