Offer git commit --amend after previous git commit (#764)

README.md

@@ -187,6 +187,7 @@ using the matched rule and runs it. Rules enabled by default are as follows:
 * `git_branch_exists` – offers `git branch -d foo`, `git branch -D foo` or `git checkout foo` when creating a branch that already exists;
 * `git_branch_list` – catches `git branch list` in place of `git branch` and removes created branch;
 * `git_checkout` – fixes branch name or creates new branch;
+* `git_commit_amend` – offers `git commit --amend` after previous commit;
 * `git_diff_no_index` – adds `--no-index` to previous `git diff` on untracked files;
 * `git_diff_staged` – adds `--staged` to previous `git diff` with unexpected output;
 * `git_fix_stash` – fixes `git stash` commands (misspelled subcommand and missing `save`);

tests/rules/test_git_commit_amend.py

@@ -0,0 +1,25 @@
+import pytest
+from thefuck.rules.git_commit_amend import match, get_new_command
+from thefuck.types import Command
+
+
+@pytest.mark.parametrize('script, output', [
+    ('git commit -m "test"', 'test output'),
+    ('git commit', '')])
+def test_match(output, script):
+    assert match(Command(script, output))
+
+
+@pytest.mark.parametrize('script', [
+    'git branch foo',
+    'git checkout feature/test_commit',
+    'git push'])
+def test_not_match(script):
+    assert not match(Command(script, ''))
+
+
+@pytest.mark.parametrize('script', [
+    ('git commit -m "test commit"'),
+    ('git commit')])
+def test_get_new_command(script):
+    assert get_new_command(Command(script, '')) == 'git commit --amend'

thefuck/rules/git_commit_amend.py

@@ -0,0 +1,11 @@
+from thefuck.specific.git import git_support
+
+
+@git_support
+def match(command):
+    return ('commit' in command.script_parts)
+
+
+@git_support
+def get_new_command(command):
+    return 'git commit --amend'