support rbenv install

tests/rules/test_rbenv_install.py

@@ -0,0 +1,25 @@
+import pytest
+from thefuck.rules.rbenv_install import match, get_new_command
+from thefuck.types import Command
+
+expected_new_command = """cd /home/alex/.rbenv/plugins/ruby-build && git pull && cd -"""
+expected_output = """ruby-build: definition not found: 2.6.1
+
+See all available versions with `rbenv install --list'.
+
+If the version you need is missing, try upgrading ruby-build:
+
+  %s""" % expected_new_command
+
+
+@pytest.mark.parametrize('script, output', [
+    ('rbenv install 2.6.1', expected_output)
+    ])
+def test_match(script, output):
+    assert match(Command(script, output))
+
+
+@pytest.mark.parametrize('command, new_command', [
+    (Command('rbenv install 2.6.1', expected_output), expected_new_command)])
+def test_get_new_command(command, new_command):
+    assert get_new_command(command) == new_command

thefuck/rules/rbenv_install.py

@@ -0,0 +1,14 @@
+from thefuck.shells import shell
+from thefuck.utils import for_app
+
+
+@for_app('rbenv')
+def match(command):
+    return ('ruby-build: definition not found' in command.output.lower() and
+            'if the version you need is missing, try upgrading ruby-build' in command.output.lower()
+            )
+
+
+def get_new_command(command):
+    output = command.output.split('\n')[-1].lstrip()
+    return shell.to_shell(output)