TST: remove some test warnings in parser tests

TST: move highmemory test to proper location in c_parser_only

xref pandas-dev#16798

Author: jreback

Diff for: pandas/conftest.py

@@ -10,7 +10,7 @@ def pytest_addoption(parser):
                      help="skip slow tests")
     parser.addoption("--skip-network", action="store_true",
                      help="skip network tests")
-    parser.addoption("--run-highmemory", action="store_true",
+    parser.addoption("--run-high-memory", action="store_true",
                      help="run high memory tests")
     parser.addoption("--only-slow", action="store_true",
                      help="run only slow tests")
@@ -27,7 +27,7 @@ def pytest_runtest_setup(item):
         pytest.skip("skipping due to --skip-network")
 
     if 'high_memory' in item.keywords and not item.config.getoption(
-            "--run-highmemory"):
+            "--run-high-memory"):
         pytest.skip(
             "skipping high memory test since --run-highmemory was not set")
 

Diff for: pandas/tests/io/parser/c_parser_only.py

@@ -476,9 +476,23 @@ def test_read_tarfile(self, tar_suffix):
         # iterating through a file-like).
         tar_path = os.path.join(self.dirpath, "tar_csv" + tar_suffix)
 
-        tar = tarfile.open(tar_path, "r")
-        data_file = tar.extractfile("tar_data.csv")
-
-        out = self.read_csv(data_file)
-        expected = pd.DataFrame({"a": [1]})
-        tm.assert_frame_equal(out, expected)
+        with tarfile.open(tar_path, "r") as tar:
+            data_file = tar.extractfile("tar_data.csv")
+
+            out = self.read_csv(data_file)
+            expected = pd.DataFrame({"a": [1]})
+            tm.assert_frame_equal(out, expected)
+
+    @pytest.mark.high_memory
+    def test_bytes_exceed_2gb(self):
+        """Read from a "CSV" that has a column larger than 2GB.
+
+        GH 16798
+        """
+        if self.low_memory:
+            pytest.skip("not a high_memory test")
+
+        csv = StringIO('strings\n' + '\n'.join(
+            ['x' * (1 << 20) for _ in range(2100)]))
+        df = self.read_csv(csv, low_memory=False)
+        assert not df.empty

Diff for: pandas/tests/io/parser/test_parsers.py

@@ -1,10 +1,6 @@
 # -*- coding: utf-8 -*-
 
 import os
-from io import StringIO
-
-import pytest
-
 import pandas.util.testing as tm
 
 from pandas import read_csv, read_table
@@ -28,18 +24,6 @@
 from .dtypes import DtypeTests
 
 
-@pytest.mark.high_memory
-def test_bytes_exceed_2gb():
-    """Read from a "CSV" that has a column larger than 2GB.
-
-    GH 16798
-    """
-    csv = StringIO('strings\n' + '\n'.join(
-        ['x' * (1 << 20) for _ in range(2100)]))
-    df = read_csv(csv, low_memory=False)
-    assert not df.empty
-
-
 class BaseParser(CommentTests, CompressionTests,
                  ConverterTests, DialectTests,
                  HeaderTests, IndexColTests,