Add type-checking to Python Fire via pytype.

PiperOrigin-RevId: 236693773
Change-Id: I8eb393b69283445b952780c288704e4b8e262628

.gitignore

@@ -98,3 +98,6 @@ ENV/
 
 # PyCharm IDE
 .idea/
+
+# Type-checking
+.pytype/

.travis.yml

@@ -15,10 +15,19 @@ before_install:
   - pip install --upgrade setuptools pip
   - pip install --upgrade pylint pytest pytest-pylint pytest-runner
 install:
-  - pip install hypothesis
+  - pip install hypothesis python-Levenshtein
   - python setup.py develop
 script:
   - python -m pytest  # Run the tests without IPython.
   - pip install ipython
   - python -m pytest  # Now run the tests with IPython.
   - pylint fire --ignore=test_components_py3.py,parser_fuzz_test.py,console
+  - pip install pytype
+  # Run type-checking, excluding files that define or use py3 features in py2.
+  - if [[ $TRAVIS_PYTHON_VERSION == 2.7 ]]; then
+      pytype -x
+        fire/fire_test.py
+        fire/inspectutils_test.py
+        fire/test_components_py3.py;
+    else
+      pytype; fi

fire/core.py

@@ -487,7 +487,7 @@ def _Fire(component, args, context, name=None):
         # If the component is a namedtuple, we need to convert it to dict to
         # be able to use the .items() method.
         if inspectutils.IsNamedTuple(component):
-          component = component._asdict()
+          component = component._asdict()  # pytype: disable=attribute-error
         for key, value in component.items():
           if target == str(key):
             component = value

fire/docstrings.py

@@ -82,7 +82,7 @@ class Namespace(dict):
   def __getattr__(self, key):
     if key not in self:
       self[key] = Namespace()
-    return self.get(key)
+    return self[key]
 
   def __setattr__(self, key, value):
     self[key] = value
@@ -398,7 +398,7 @@ def _consume_line(line_info, state):
   if state.section.new and state.section.format == Formats.RST:
     # The current line starts with an RST directive, e.g. ":param arg:".
     directive = _get_directive(line_info)
-    directive_tokens = directive.split()
+    directive_tokens = directive.split()  # pytype: disable=attribute-error
     if state.section.title == Sections.ARGS:
       name = directive_tokens[-1]
       arg = _get_or_create_arg_by_name(state, name)

fire/trace.py

@@ -65,7 +65,9 @@ def __init__(self, initial_component, name=None, separator='-', verbose=False,
 
   def GetResult(self):
     """Returns the component from the last element of the trace."""
+    # pytype: disable=attribute-error
     return self.GetLastHealthyElement().component
+    # pytype: enable=attribute-error
 
   def GetLastHealthyElement(self):
     """Returns the last element of the trace that is not an error.

setup.cfg

@@ -9,3 +9,7 @@ test = pytest
 
 [tool:pytest]
 addopts = --ignore=fire/test_components_py3.py --ignore=fire/parser_fuzz_test.py
+
+[pytype]
+inputs = .
+output = .pytype