Respond to review feedback

.pre-commit-hooks.yaml

diff --git a/.pre-commit-hooks.yaml b/.pre-commit-hooks.yaml
index d501d50..eea7bed 100644
--- a/.pre-commit-hooks.yaml
+++ b/.pre-commit-hooks.yaml
@@ -110,7 +110,7 @@
     description: Sort the lines in specified files (defaults to alphabetical). You must provide list of target files as input in your .pre-commit-config.yaml file.
     entry: file-contents-sorter
     language: python
-    files: ''
+    files: '^$'
 -   id: fix-encoding-pragma
     name: Fix python encoding pragma
     language: python

pre_commit_hooks/file_contents_sorter.py

diff --git a/pre_commit_hooks/file_contents_sorter.py b/pre_commit_hooks/file_contents_sorter.py
index 06c6d3a..e01eb8c 100644
--- a/pre_commit_hooks/file_contents_sorter.py
+++ b/pre_commit_hooks/file_contents_sorter.py
@@ -18,7 +18,7 @@
 
 
 def sort_file_contents(f):
-    before = [line for line in f]
+    before = list(f)
     after = sorted(before)
 
     before_string = b''.join(before)

requirements-dev.txt

diff --git a/requirements-dev.txt b/requirements-dev.txt
index 4070e66..2922ef5 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -2,7 +2,6 @@
 
 coverage
 flake8
-ipdb
 mock
 pre-commit
 pytest

tests/file_contents_sorter_test.py

diff --git a/tests/file_contents_sorter_test.py b/tests/file_contents_sorter_test.py
index 4e65629..e8f1ea8 100644
--- a/tests/file_contents_sorter_test.py
+++ b/tests/file_contents_sorter_test.py
@@ -6,21 +6,17 @@
 from pre_commit_hooks.file_contents_sorter import PASS
 
 
-def _n(*strs):
-    return b'\n'.join(strs) + b'\n'
-
-
 # Input, expected return value, expected output
 TESTS = (
     (b'', PASS, b''),
-    (_n(b'lonesome'), PASS, _n(b'lonesome')),
+    (b'lonesome\n', PASS, b'lonesome\n'),
     (b'missing_newline', PASS, b'missing_newline'),
-    (_n(b'alpha', b'beta'), PASS, _n(b'alpha', b'beta')),
-    (_n(b'beta', b'alpha'), FAIL, _n(b'alpha', b'beta')),
-    (_n(b'C', b'c'), PASS, _n(b'C', b'c')),
-    (_n(b'c', b'C'), FAIL, _n(b'C', b'c')),
-    (_n(b'mag ical ', b' tre vor'), FAIL, _n(b' tre vor', b'mag ical ')),
-    (_n(b'@', b'-', b'_', b'#'), FAIL, _n(b'#', b'-', b'@', b'_')),
+    (b'alpha\nbeta\n', PASS, b'alpha\nbeta\n'),
+    (b'beta\nalpha\n', FAIL, b'alpha\nbeta\n'),
+    (b'C\nc\n', PASS, b'C\nc\n'),
+    (b'c\nC\n', FAIL, b'C\nc\n'),
+    (b'mag ical \n tre vor\n', FAIL, b' tre vor\nmag ical \n'),
+    (b'@\n-\n_\n#\n', FAIL, b'#\n-\n@\n_\n'),
 )