Add "fix-lint" tox environment to fix linting errors

testing/code/test_source_multiline_block.py

@@ -0,0 +1,26 @@
+# flake8: noqa
+import sys
+
+import _pytest._code
+
+
+def test_getstartingblock_multiline():
+    """
+    This test was originally found in test_source.py, but it depends on the weird
+    formatting of the ``x = A`` construct seen here and our autopep8 tool can only exclude entire
+    files (it does not support excluding lines/blocks using the traditional #noqa comment yet,
+    see hhatto/autopep8#307). It was considered better to just move this single test to its own
+    file and exclude it from autopep8 than try to complicate things.
+    """
+    class A(object):
+        def __init__(self, *args):
+            frame = sys._getframe(1)
+            self.source = _pytest._code.Frame(frame).statement
+
+    x = A('x',
+          'y'
+          ,
+          'z')
+
+    l = [i for i in x.source.lines if i.strip()]
+    assert len(l) == 4