Update configs and instructions for running tests manually. (python#1137

)

- Switch requirements-tests-py3.txt to use mypy GitHub master.
- Exclude .venv{2,3} (suggested in README.md) in .flake8 and .gitignore.
- Update instructions in README.md to be working.
- Remove runtests.sh script and mentions of it -- I can't get it to work
  and the three steps are easily run by hand.

.flake8

@@ -19,3 +19,4 @@ ignore = F401, F811, E127, E128, E301, E302, E305, E501, E701, E704, B303
 # A nice future improvement would be to provide separate .flake8
 # configurations for Python 2 and Python 3 files.
 builtins = StandardError,apply,basestring,buffer,cmp,coerce,execfile,file,intern,long,raw_input,reduce,reload,unichr,unicode,xrange
+exclude = .venv*,@*

.gitignore

@@ -61,3 +61,4 @@ analyze.py
 .*.sw?
 .vscode/
 .idea/
+.venv*/

README.md

@@ -79,30 +79,33 @@ The tests are automatically run by Travis CI on every PR and push to
 the repo.  There are two separate sets of tests: `tests/mypy_test.py`
 runs tests against [mypy](https://github.com/python/mypy/), while
 `tests/pytype_tests.py` runs tests against
-[pytype](https://github.com/google/pytype/).  The script runtests.sh
-runs both sets of tests and flake8 over all .pyi files.
+[pytype](https://github.com/google/pytype/).
 
 Both sets of tests are shallow -- they verify that all stubs can be
 imported but they don't check whether stubs match their implementation
 (in the Python standard library or a third-party package).  Also note
 that each set of tests has a blacklist of modules that are not tested
 at all.  The blacklists also live in the tests directory.
 
-To manually run the mypy tests, you need to have Python 3.5 or higher.
+To manually run the mypy tests, you need to have Python 3.5 or higher;
+Python 3.6.1 or higher is recommended.
 Run:
 ```
-$ python3.5 -m venv .venv3
+$ python3.6 -m venv .venv3
 $ source .venv3/bin/activate
-(.venv3)$ pip install -r requirements-tests-py3.txt
+(.venv3)$ pip3 install -r requirements-tests-py3.txt
 ```
-This will install mypy-lang, typed-ast, and flake8. You can then run
-mypy tests and flake8 tests by invoking:
+This will install mypy (you need the latest master branch from GitHub),
+typed-ast, and flake8. You can then run mypy tests and flake8 tests by
+invoking:
 ```
-(.venv3)$ python tests/mypy_test.py
+(.venv3)$ python3 tests/mypy_test.py
 ...
 (.venv3)$ flake8
 ...
 ```
+(Note that flake8 only works with Python 3.6 or higher.)
+
 To run the pytype tests, you need a separate virtual environment with
 Python 2.7. Run:
 ```
@@ -116,25 +119,6 @@ tests by running:
 (.venv2)$ python tests/pytype_test.py
 ```
 
-To be able to everything with ``runtests.sh``, copy the ``pytype`` script
-from the Python 2 virtualenv to the Python 3 one:
-```
-$ cp .venv2/bin/pytype .venv3/bin/pytype
-$ source .venv3/bin/activate
-(.venv3)$ ./runtests.sh
-running mypy --python-version 3.6 --strict-optional # with 479 files
-running mypy --python-version 3.5 --strict-optional # with 469 files
-running mypy --python-version 3.4 --strict-optional # with 469 files
-running mypy --python-version 3.3 --strict-optional # with 454 files
-running mypy --python-version 3.2 --strict-optional # with 453 files
-running mypy --python-version 2.7 --strict-optional # with 502 files
-Running pytype tests...
-Ran pytype with 244 pyis, got 0 errors.
-Running flake8...
-flake8 run clean.
-(.venv3)$
-```
-
 For mypy, if you are in the typeshed repo that is submodule of the
 mypy repo (so `..` refers to the mypy repo), there's a shortcut to run
 the mypy tests that avoids installing mypy:

requirements-tests-py3.txt

@@ -1,4 +1,4 @@
-mypy>=0.501
+git+https://github.com/python/mypy.git@master
 typed-ast>=1.0.2
 flake8==3.3.0
 flake8-bugbear>=17.3.0