Create 'pre-commit', add Python tests

* Create our 'pre-commit' hook script that runs flake8 on Python files in
  the staging area.
* Update test setup to create a git repository for testing.
* Add a test for the Python linter to confirm that it produces the
  correct output when trying to commit and that it only checks files in
  the staging index.

1 files changed, 29 insertions, 0 deletions

diff --git a/t/100-python.t b/t/100-python.t
new file mode 100644
index 0000000..8e9b403
--- /dev/null
+++ b/t/100-python.t
@@ -0,0 +1,29 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+use Test::More;
+
+chdir 't/git-repo/' or die $!;
+
+system('cp ../*.py .');
+ok !$?;
+
+my $output = `ls -1`;
+
+ok $output eq 'test.py
+uncommitted.py
+', 'Both test Python files are present';
+
+system('git add test.py');
+ok !$?;
+
+$output = `git commit 2>&1`;
+
+ok $output eq "test.py:1:1: F401 'datetime' imported but unused
+test.py:3:80: E501 line too long (97 > 79 characters)
+test.py:5:31: E225 missing whitespace around operator
+", 'flake8 ran on committed Python file';
+
+done_testing;