Greatly simplify fix_open

Use run ordering to prevent having to subclass.

Author: brettcannon

libmodernize/fixes/fix_open.py

@@ -1,19 +1,15 @@
-from libmodernize.fixes import fix_file
 from lib2to3 import fixer_base
 from lib2to3.fixer_util import touch_import
 
 
-class FixOpen(fix_file.FixFile):
+class FixOpen(fixer_base.BaseFix):
 
+    run_order = 10  # Must run after fix_file.
     BM_compatible = True
-    order = "pre"
-
+    # Fixers don't directly stack, so make sure the 'file' case is covered.
     PATTERN = """
-    power< name=('open'|'file') trailer< '(' any+ ')' > any* >
+    power< ('open' | 'file') trailer< '(' any+ ')' > >
     """
 
     def transform(self, node, results):
         touch_import(u'io', u'open', node)
-        if len(results['name']) == 1 and results['name'][0].value == 'file':
-            results['name'] = results['name'][0]
-            super(FixOpen, self).transform(node, results)

tests/test_fix_open.py

@@ -2,25 +2,21 @@
 
 
 OPEN = ("""\
-open('some/path')
-""", """\
-from io import open
-open('some/path')
-""")
-
-FILE = ("""\
-file('some/path')
+{0}('some/path')
 """, """\
 from io import open
 open('some/path')
 """)
 
 
 def test_open():
-    check_on_input(*OPEN, extra_flags=['-f', 'libmodernize.fixes.fix_open'])
+    check_on_input(OPEN[0].format('open'), OPEN[1],
+                   extra_flags=['-f', 'libmodernize.fixes.fix_open'])
 
 def test_open_optional():
-    check_on_input(OPEN[0], OPEN[0])
+    check_on_input(OPEN[0].format('open'), OPEN[0].format('open'))
 
 def test_file():
-    check_on_input(*FILE, extra_flags=['-f', 'libmodernize.fixes.fix_open'])
+    flags = ['-f', 'libmodernize.fixes.fix_open',
+             '-f', 'libmodernize.fixes.fix_file']
+    check_on_input(OPEN[0].format('file'), OPEN[1], extra_flags=flags)