New component: Python Script (#7950)

* Add initial version

* Fix requirements

* Prefer logging over printing

* Set executor thread name on >Py36 only

* Add tests

* Lint

* Add restrictedpython to test dependencies

* Create python_script.py

From doc:
```
However, an empty dict ({}) is treated as is. If you want to specify a list that can contain anything, specify it as dict:
>>> schema = Schema({}, extra=ALLOW_EXTRA)  # don't do this
>>> try:
...   schema({'extra': 1})
...   raise AssertionError('MultipleInvalid not raised')
... except MultipleInvalid as e:
...   exc = e
>>> str(exc) == "not a valid value"
True
>>> schema({})
{}
>>> schema = Schema(dict)  # do this instead
>>> schema({})
{}
>>> schema({'extra': 1})
{'extra': 1}

```

tests/components/test_python_script.py

@@ -0,0 +1,123 @@
+"""Test the python_script component."""
+import asyncio
+import logging
+from unittest.mock import patch, mock_open
+
+from homeassistant.setup import async_setup_component
+from homeassistant.components.python_script import execute
+
+
+@asyncio.coroutine
+def test_setup(hass):
+    """Test we can discover scripts."""
+    scripts = [
+        '/some/config/dir/python_scripts/hello.py',
+        '/some/config/dir/python_scripts/world_beer.py'
+    ]
+    with patch('homeassistant.components.python_script.os.path.isdir',
+               return_value=True), \
+            patch('homeassistant.components.python_script.glob.iglob',
+                  return_value=scripts):
+        res = yield from async_setup_component(hass, 'python_script', {})
+
+    assert res
+    assert hass.services.has_service('python_script', 'hello')
+    assert hass.services.has_service('python_script', 'world_beer')
+
+    with patch('homeassistant.components.python_script.open',
+               mock_open(read_data='fake source'), create=True), \
+            patch('homeassistant.components.python_script.execute') as mock_ex:
+        yield from hass.services.async_call(
+            'python_script', 'hello', {'some': 'data'}, blocking=True)
+
+    assert len(mock_ex.mock_calls) == 1
+    hass, script, source, data = mock_ex.mock_calls[0][1]
+
+    assert hass is hass
+    assert script == 'hello.py'
+    assert source == 'fake source'
+    assert data == {'some': 'data'}
+
+
+@asyncio.coroutine
+def test_setup_fails_on_no_dir(hass, caplog):
+    """Test we fail setup when no dir found."""
+    with patch('homeassistant.components.python_script.os.path.isdir',
+               return_value=False):
+        res = yield from async_setup_component(hass, 'python_script', {})
+
+    assert not res
+    assert 'Folder python_scripts not found in config folder' in caplog.text
+
+
+@asyncio.coroutine
+def test_execute_with_data(hass, caplog):
+    """Test executing a script."""
+    caplog.set_level(logging.WARNING)
+    source = """
+hass.states.set('test.entity', data.get('name', 'not set'))
+    """
+
+    hass.async_add_job(execute, hass, 'test.py', source, {'name': 'paulus'})
+    yield from hass.async_block_till_done()
+
+    assert hass.states.is_state('test.entity', 'paulus')
+
+    # No errors logged = good
+    assert caplog.text == ''
+
+
+@asyncio.coroutine
+def test_execute_warns_print(hass, caplog):
+    """Test print triggers warning."""
+    caplog.set_level(logging.WARNING)
+    source = """
+print("This triggers warning.")
+    """
+
+    hass.async_add_job(execute, hass, 'test.py', source, {})
+    yield from hass.async_block_till_done()
+
+    assert "Don't use print() inside scripts." in caplog.text
+
+
+@asyncio.coroutine
+def test_execute_logging(hass, caplog):
+    """Test logging works."""
+    caplog.set_level(logging.INFO)
+    source = """
+logger.info('Logging from inside script')
+    """
+
+    hass.async_add_job(execute, hass, 'test.py', source, {})
+    yield from hass.async_block_till_done()
+
+    assert "Logging from inside script" in caplog.text
+
+
+@asyncio.coroutine
+def test_execute_compile_error(hass, caplog):
+    """Test compile error logs error."""
+    caplog.set_level(logging.ERROR)
+    source = """
+this is not valid Python
+    """
+
+    hass.async_add_job(execute, hass, 'test.py', source, {})
+    yield from hass.async_block_till_done()
+
+    assert "Error loading script test.py" in caplog.text
+
+
+@asyncio.coroutine
+def test_execute_runtime_error(hass, caplog):
+    """Test compile error logs error."""
+    caplog.set_level(logging.ERROR)
+    source = """
+raise Exception('boom')
+    """
+
+    hass.async_add_job(execute, hass, 'test.py', source, {})
+    yield from hass.async_block_till_done()
+
+    assert "Error executing script test.py" in caplog.text