basic support for the hdfs dfs <command> when the command misses the dash

README.md

@@ -192,6 +192,7 @@ using the matched rule and runs it. Rules enabled by default are as follows:
 * `tsuru_not_command` – fixes wrong tsuru commands like `tsuru shell`;
 * `tmux` – fixes `tmux` commands;
 * `whois` – fixes `whois` command.
+* `hdfs dfs` – Add the missing dash to the command.
 
 Enabled by default only on specific platforms:
 

tests/rules/test_hadoop_dfs_missing_dash.py

@@ -0,0 +1,30 @@
+import pytest
+from thefuck.rules.hadoop_dfs_missing_dash import match, get_new_command
+from tests.utils import Command
+
+
+@pytest.mark.parametrize('command', [
+    Command(script='./bin/hdfs dfs ls', stderr='ls: Unknown command\nDid you mean -ls?  This command begins with a dash.'),
+    Command(script='hdfs dfs ls',
+            stderr='ls: Unknown command\nDid you mean -ls?  This command begins with a dash.'),
+    Command(script='hdfs dfs ls /foo/bar', stderr='ls: Unknown command\nDid you mean -ls?  This command begins with a dash.')])
+def test_match(command):
+    assert match(command, None)
+
+
+@pytest.mark.parametrize('command', [
+    Command(script='./bin/hdfs dfs -ls', stderr=''),
+    Command(script='./bin/hdfs dfs -ls /foo/bar', stderr=''),  
+    Command(script='hdfs dfs -ls -R /foo/bar', stderr=''),  
+    Command()])
+def test_not_match(command):
+    assert not match(command, None)
+
+
+@pytest.mark.parametrize('command, new_command', [
+    (Command('hdfs dfs ls'), 'hdfs dfs -ls'),
+    (Command('hdfs dfs ls /foo/bar'), 'hdfs dfs -ls /foo/bar'),
+    (Command('./bin/hdfs dfs ls -R /foo/bar'), './bin/hdfs dfs -ls -R /foo/bar')])
+def test_get_new_command(command, new_command):
+    assert get_new_command(command, None) == new_command
+

thefuck/rules/hadoop_dfs_missing_dash.py

@@ -0,0 +1,10 @@
+def match(command, settings):
+    return ('hdfs dfs' in command.script
+            and "this command begins with a dash." in command.stderr.lower())
+
+
+def get_new_command(command, settings):
+    data = command.script.split()
+    data[2] = '-' + data[2]
+    return ' '.join(data)
+