Make mypy succeed with imports on master.py

We get little benefit from our mypy QA checks at the moment, because we skip
imports. This patch is what's needed to make mypy succeed with imports on a
single file: master.py

It also updates mypy to the current version, and enables a QA check.

Mypy bugs I encountered:

dict.update with kwargs not supported:

https://github.com/python/mypy/issues/1031

property setters and getters must be adjacent:

https://github.com/python/mypy/issues/1465

2 files changed, 9 insertions, 9 deletions

diff --git a/mitmproxy/utils/strutils.py b/mitmproxy/utils/strutils.py
index 29465615..1b90c2e5 100644
--- a/mitmproxy/utils/strutils.py
+++ b/mitmproxy/utils/strutils.py
@@ -1,11 +1,11 @@
 import re
 import codecs
-from typing import AnyStr, Optional
+from typing import AnyStr, Optional, cast
 
 
 def always_bytes(str_or_bytes: Optional[AnyStr], *encode_args) -> Optional[bytes]:
     if isinstance(str_or_bytes, bytes) or str_or_bytes is None:
-        return str_or_bytes
+        return cast(Optional[bytes], str_or_bytes)
     elif isinstance(str_or_bytes, str):
         return str_or_bytes.encode(*encode_args)
     else:
@@ -18,7 +18,7 @@ def always_str(str_or_bytes: Optional[AnyStr], *decode_args) -> Optional[str]:
         str_or_bytes unmodified, if
     """
     if isinstance(str_or_bytes, str) or str_or_bytes is None:
-        return str_or_bytes
+        return cast(Optional[str], str_or_bytes)
     elif isinstance(str_or_bytes, bytes):
         return str_or_bytes.decode(*decode_args)
     else:
diff --git a/mitmproxy/utils/typecheck.py b/mitmproxy/utils/typecheck.py
index bdd83ee6..e8e2121e 100644
--- a/mitmproxy/utils/typecheck.py
+++ b/mitmproxy/utils/typecheck.py
@@ -25,10 +25,10 @@ def check_type(name: str, value: typing.Any, typeinfo: type) -> None:
 
     if typename.startswith("typing.Union"):
         try:
-            types = typeinfo.__args__
+            types = typeinfo.__args__  # type: ignore
         except AttributeError:
             # Python 3.5.x
-            types = typeinfo.__union_params__
+            types = typeinfo.__union_params__  # type: ignore
 
         for T in types:
             try:
@@ -40,10 +40,10 @@ def check_type(name: str, value: typing.Any, typeinfo: type) -> None:
         raise e
     elif typename.startswith("typing.Tuple"):
         try:
-            types = typeinfo.__args__
+            types = typeinfo.__args__  # type: ignore
         except AttributeError:
             # Python 3.5.x
-            types = typeinfo.__tuple_params__
+            types = typeinfo.__tuple_params__  # type: ignore
 
         if not isinstance(value, (tuple, list)):
             raise e
@@ -54,10 +54,10 @@ def check_type(name: str, value: typing.Any, typeinfo: type) -> None:
         return
     elif typename.startswith("typing.Sequence"):
         try:
-            T = typeinfo.__args__[0]
+            T = typeinfo.__args__[0]  # type: ignore
         except AttributeError:
             # Python 3.5.0
-            T = typeinfo.__parameters__[0]
+            T = typeinfo.__parameters__[0]  # type: ignore
 
         if not isinstance(value, (tuple, list)):
             raise e