Merge branch 'josephfrazier-yarn_help'

README.md

@@ -250,6 +250,7 @@ using the matched rule and runs it. Rules enabled by default are as follows:
 * `workon_doesnt_exists` – fixes `virtualenvwrapper` env name os suggests to create new.
 * `yarn_alias` – fixes aliased `yarn` commands like `yarn ls`;
 * `yarn_command_not_found` – fixes misspelled `yarn` commands;
+* `yarn_help` – makes it easier to open `yarn` documentation;
 
 Enabled by default only on specific platforms:
 

tests/rules/test_yarn_help.py

@@ -0,0 +1,57 @@
+import pytest
+from thefuck.rules.yarn_help import match, get_new_command
+from tests.utils import Command
+from thefuck.system import open_command
+
+
+stdout_clean = '''
+
+  Usage: yarn [command] [flags]
+
+  Options:
+
+    -h, --help                      output usage information
+    -V, --version                   output the version number
+    --verbose                       output verbose messages on internal operations
+    --offline                       trigger an error if any required dependencies are not available in local cache
+    --prefer-offline                use network only if dependencies are not available in local cache
+    --strict-semver                 
+    --json                          
+    --ignore-scripts                don't run lifecycle scripts
+    --har                           save HAR output of network traffic
+    --ignore-platform               ignore platform checks
+    --ignore-engines                ignore engines check
+    --ignore-optional               ignore optional dependencies
+    --force                         ignore all caches
+    --no-bin-links                  don't generate bin links when setting up packages
+    --flat                          only allow one version of a package
+    --prod, --production [prod]     
+    --no-lockfile                   don't read or generate a lockfile
+    --pure-lockfile                 don't generate a lockfile
+    --frozen-lockfile               don't generate a lockfile and fail if an update is needed
+    --link-duplicates               create hardlinks to the repeated modules in node_modules
+    --global-folder <path>          
+    --modules-folder <path>         rather than installing modules into the node_modules folder relative to the cwd, output them here
+    --cache-folder <path>           specify a custom folder to store the yarn cache
+    --mutex <type>[:specifier]      use a mutex to ensure only one yarn instance is executing
+    --no-emoji                      disable emoji in output
+    --proxy <host>                  
+    --https-proxy <host>            
+    --no-progress                   disable progress bar
+    --network-concurrency <number>  maximum number of concurrent network requests
+
+  Visit https://yarnpkg.com/en/docs/cli/clean for documentation about this command.
+'''  # noqa
+
+
+@pytest.mark.parametrize('command', [
+    Command(script='yarn help clean', stdout=stdout_clean)])
+def test_match(command):
+    assert match(command)
+
+
+@pytest.mark.parametrize('command, new_command', [
+    (Command('yarn help clean', stdout=stdout_clean),
+     open_command('https://yarnpkg.com/en/docs/cli/clean'))])
+def test_get_new_command(command, new_command):
+    assert get_new_command(command) == new_command

thefuck/rules/yarn_help.py

@@ -0,0 +1,17 @@
+import re
+from thefuck.utils import for_app
+from thefuck.system import open_command
+
+
+@for_app('yarn', at_least=2)
+def match(command):
+    return (command.script_parts[1] == 'help'
+            and 'for documentation about this command.' in command.stdout)
+
+
+def get_new_command(command):
+    url = re.findall(
+        r'Visit ([^ ]*) for documentation about this command.',
+        command.stdout)[0]
+
+    return open_command(url)

thefuck/system/unix.py

@@ -3,6 +3,7 @@ import sys
 import tty
 import termios
 import colorama
+from distutils.spawn import find_executable
 from .. import const
 
 init_output = colorama.init
@@ -35,6 +36,13 @@ def get_key():
 
     return ch
 
+
+def open_command(arg):
+    if find_executable('xdg-open'):
+        return 'xdg-open ' + arg
+    return 'open ' + arg
+
+
 try:
     from pathlib import Path
 except ImportError:

thefuck/system/win32.py

@@ -23,9 +23,15 @@ def get_key():
     if ch == b'P':
         return const.KEY_DOWN
 
-    encoding = sys.stdout.encoding or os.environ.get('PYTHONIOENCODING', 'utf-8')
+    encoding = (sys.stdout.encoding
+                or os.environ.get('PYTHONIOENCODING', 'utf-8'))
     return ch.decode(encoding)
 
+
+def open_command(arg):
+    return 'cmd /c start ' + arg
+
+
 try:
     from pathlib import Path
 except ImportError: