Refactor black into packages in src/ dir (#1376)

- Move black.py to src/black/__init__.py
- Have setuptools_scm make src/_black_version.py and exclude from git
- Move blackd.py to src/blackd/__init__.py
- Move blib2to3/ to src/
- Update `setup.py`
- Update unittests to pass
  - Mostly path fixing + resolving
- Update CI
  - pre-commit config
  - appveyor + travis

Tested on my mac with python 3.7.5 via:
```
python3 -m venv /tmp/tb3
/tmp/tb3/bin/pip install --upgrade setuptools pip coverage pre-commit
/tmp/tb2/bin/pip install ~/repos/black/
cd ~/repos/black/
/tmp/tb2/bin/coverage run tests/test_black.py
/tmp/tb3/bin/pre-commit run -a
/tmp/tb3/bin/black --help
/tmp/tb3/bin/black ~/repos/ptr/ptr.py
```

.appveyor.yml

@@ -7,12 +7,12 @@ build: off
 
 test_script:
   - C:\Python36\python.exe tests/test_black.py
-  - C:\Python36\python.exe -m mypy black.py blackd.py tests/test_black.py blib2to3
+  - C:\Python36\python.exe -m mypy src/black src/blackd tests/test_black.py src/blib2to3
 
 after_test:
   - C:\Python36\python.exe -m pip install pyinstaller
   - "%CMD_IN_ENV% C:\\Python36\\python.exe -m PyInstaller --clean -F --add-data
-    blib2to3/;blib2to3 black.py"
+    src/blib2to3/;blib2to3 src/black/__init__.py"
 
 artifacts:
   - path: dist/black.exe

.coveragerc

@@ -1,5 +1,5 @@
 [report]
 omit =
-  blib2to3/*
+  src/blib2to3/*
   tests/data/*
   */site-packages/*

.gitignore

@@ -9,7 +9,7 @@ black.egg-info
 build/
 dist/
 pip-wheel-metadata/
-_black_version.py
+src/_black_version.py
 .idea
 .eggs
 .dmypy.json

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 # Note: don't use this config for your own repositories. Instead, see
 # "Version control integration" in README.md.
-exclude: ^(blib2to3/|profiling/|tests/data/)
+exclude: ^(src/blib2to3/|profiling/|tests/data/)
 repos:
   - repo: local
     hooks:

.travis.yml

@@ -33,7 +33,7 @@ matrix:
     - python: 3.9-dev
 before_deploy:
   - pip install pyinstaller
-  - pyinstaller --clean -F --add-data blib2to3/:blib2to3 black.py
+  - pyinstaller --clean -F --add-data src/blib2to3/:blib2to3 src/black/__init__.py
 deploy:
   provider: releases
   api_key:

setup.py

@@ -1,4 +1,4 @@
-# Copyright (C) 2018 Łukasz Langa
+# Copyright (C) 2020 Łukasz Langa
 from setuptools import setup
 import sys
 import os
@@ -28,14 +28,14 @@ def get_long_description() -> str:
 
 if USE_MYPYC:
     mypyc_targets = [
-        "black.py",
-        "blib2to3/pytree.py",
-        "blib2to3/pygram.py",
-        "blib2to3/pgen2/parse.py",
-        "blib2to3/pgen2/grammar.py",
-        "blib2to3/pgen2/token.py",
-        "blib2to3/pgen2/driver.py",
-        "blib2to3/pgen2/pgen.py",
+        "src/black/__init__.py",
+        "src/blib2to3/pytree.py",
+        "src/blib2to3/pygram.py",
+        "src/blib2to3/pgen2/parse.py",
+        "src/blib2to3/pgen2/grammar.py",
+        "src/blib2to3/pgen2/token.py",
+        "src/blib2to3/pgen2/driver.py",
+        "src/blib2to3/pgen2/pgen.py",
     ]
 
     from mypyc.build import mypycify
@@ -48,7 +48,7 @@ def get_long_description() -> str:
 setup(
     name="black",
     use_scm_version={
-        "write_to": "_black_version.py",
+        "write_to": "src/_black_version.py",
         "write_to_template": 'version = "{version}"\n',
     },
     description="The uncompromising code formatter.",
@@ -60,9 +60,10 @@ def get_long_description() -> str:
     url="https://github.com/psf/black",
     project_urls={"Changelog": "https://github.com/psf/black/blob/master/CHANGES.md"},
     license="MIT",
-    py_modules=["black", "blackd", "_black_version"],
+    py_modules=["_black_version"],
     ext_modules=ext_modules,
-    packages=["blib2to3", "blib2to3.pgen2"],
+    packages=["blackd", "black", "blib2to3", "blib2to3.pgen2"],
+    package_dir={"": "src"},
     package_data={"blib2to3": ["*.txt"]},
     python_requires=">=3.6",
     zip_safe=False,

tests/test_black.py

@@ -35,6 +35,7 @@
 fs = partial(black.format_str, mode=black.FileMode())
 THIS_FILE = Path(__file__)
 THIS_DIR = THIS_FILE.parent
+PROJECT_ROOT = THIS_DIR.parent
 DETERMINISTIC_HEADER = "[Deterministic header]"
 EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
 PY36_ARGS = [
@@ -54,7 +55,7 @@ def read_data(name: str, data: bool = True) -> Tuple[str, str]:
         name += ".py"
     _input: List[str] = []
     _output: List[str] = []
-    base_dir = THIS_DIR / "data" if data else THIS_DIR
+    base_dir = THIS_DIR / "data" if data else PROJECT_ROOT
     with open(base_dir / name, "r", encoding="utf8") as test:
         lines = test.readlines()
     result = _input
@@ -202,43 +203,43 @@ def test_self(self) -> None:
         self.checkSourceFile("tests/test_black.py")
 
     def test_black(self) -> None:
-        self.checkSourceFile("black.py")
+        self.checkSourceFile("src/black/__init__.py")
 
     def test_pygram(self) -> None:
-        self.checkSourceFile("blib2to3/pygram.py")
+        self.checkSourceFile("src/blib2to3/pygram.py")
 
     def test_pytree(self) -> None:
-        self.checkSourceFile("blib2to3/pytree.py")
+        self.checkSourceFile("src/blib2to3/pytree.py")
 
     def test_conv(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/conv.py")
+        self.checkSourceFile("src/blib2to3/pgen2/conv.py")
 
     def test_driver(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/driver.py")
+        self.checkSourceFile("src/blib2to3/pgen2/driver.py")
 
     def test_grammar(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/grammar.py")
+        self.checkSourceFile("src/blib2to3/pgen2/grammar.py")
 
     def test_literals(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/literals.py")
+        self.checkSourceFile("src/blib2to3/pgen2/literals.py")
 
     def test_parse(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/parse.py")
+        self.checkSourceFile("src/blib2to3/pgen2/parse.py")
 
     def test_pgen(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/pgen.py")
+        self.checkSourceFile("src/blib2to3/pgen2/pgen.py")
 
     def test_tokenize(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/tokenize.py")
+        self.checkSourceFile("src/blib2to3/pgen2/tokenize.py")
 
     def test_token(self) -> None:
-        self.checkSourceFile("blib2to3/pgen2/token.py")
+        self.checkSourceFile("src/blib2to3/pgen2/token.py")
 
     def test_setup(self) -> None:
         self.checkSourceFile("setup.py")
 
     def test_piping(self) -> None:
-        source, expected = read_data("../black", data=False)
+        source, expected = read_data("src/black/__init__", data=False)
         result = BlackRunner().invoke(
             black.main,
             ["-", "--fast", f"--line-length={black.DEFAULT_LINE_LENGTH}"],
@@ -1663,7 +1664,7 @@ def test_assert_equivalent_different_asts(self) -> None:
 
     def test_symlink_out_of_root_directory(self) -> None:
         path = MagicMock()
-        root = THIS_DIR
+        root = THIS_DIR.resolve()
         child = MagicMock()
         include = re.compile(black.DEFAULT_INCLUDES)
         exclude = re.compile(black.DEFAULT_EXCLUDES)