tests: add basic type checking with mypy

.gitignore

@@ -7,6 +7,7 @@ build/
 mock*/
 nose*/
 .pybuild/
+.mypy_cache/
 debian/files
 debian/python-influxdb.debhelper.log
 debian/python-influxdb.postinst.debhelper

.travis.yml

@@ -31,6 +31,8 @@ matrix:
       env: TOX_ENV=flake8
     - python: 3.7
       env: TOX_ENV=coverage
+    - python: 3.7
+      env: TOX_ENV=mypy
 
 install:
     - pip install tox-travis

influxdb/dataframe_client.py

@@ -25,4 +25,4 @@ def __init__(self, *a, **kw):
             raise ImportError("DataFrameClient requires Pandas "
                               "which couldn't be imported: %s" % self.err)
 else:
-    from ._dataframe_client import DataFrameClient
+    from ._dataframe_client import DataFrameClient  # type: ignore

influxdb/tests/server_tests/base.py

@@ -51,8 +51,15 @@ class SingleTestCaseWithServerMixin(object):
     # 'influxdb_template_conf' attribute must be set
     # on the TestCase class or instance.
 
-    setUp = _setup_influxdb_server
-    tearDown = _teardown_influxdb_server
+    @classmethod
+    def setUp(cls):
+        """Set up an instance of the SingleTestCaseWithServerMixin."""
+        _setup_influxdb_server(cls)
+
+    @classmethod
+    def tearDown(cls):
+        """Tear down an instance of the SingleTestCaseWithServerMixin."""
+        _teardown_influxdb_server(cls)
 
 
 class ManyTestCasesWithServerMixin(object):

mypy.ini

@@ -0,0 +1,8 @@
+[mypy]
+ignore_missing_imports = True
+warn_unused_ignores = True
+warn_unused_configs = True
+warn_redundant_casts = True
+warn_no_return = True
+no_implicit_optional = True
+strict_equality = True

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27, py35, py36, py37, pypy, pypy3, flake8, pep257, coverage, docs
+envlist = py27, py35, py36, py37, pypy, pypy3, flake8, pep257, coverage, docs, mypy
 
 [testenv]
 passenv = INFLUXDB_PYTHON_INFLUXD_PATH
@@ -44,6 +44,11 @@ deps = -r{toxinidir}/requirements.txt
        sphinx_rtd_theme
 commands = sphinx-build -b html docs/source docs/build
 
+[testenv:mypy]
+deps = -r{toxinidir}/test-requirements.txt
+       mypy==0.720
+commands = mypy --config-file mypy.ini -p influxdb
+
 [flake8]
 ignore = W503,W504,W605,N802,F821,E402
 # W503: Line break occurred before a binary operator