Add bootstrap.py for dev env bootstrapping

Author: yanne

CONTRIBUTING.md

@@ -18,11 +18,13 @@ Install Python, nodejs and yarn.
 - https://nodejs.org/
 - https://classic.yarnpkg.com/en/docs/install
 
-Create a Python virtualenv e.g. with https://docs.python.org/3/library/venv.html.
-The minimum Python version is 3.8.
+N.B The minimum Python version is 3.8.
+
+Run `python bootsrap.py` to create a virtual environment with correct dependencies.
+After that, make sure to activate the virtual env before running other development commands.
 
 ```
-python -m venv .venv
+python bootstrap.py
 source .venv/bin/activate  # On linux and OSX
 .venv\Scripts\activate.bat  # On Windows
 ```

bootstrap.py

@@ -0,0 +1,39 @@
+"""Creates a virtual environment for developing the library.
+
+Also installs the needed dependencies.
+"""
+
+from pathlib import Path
+import platform
+import subprocess
+import sys
+from venv import EnvBuilder
+
+venv_dir = Path(".") / ".venv"
+src_dir = Path(".") / "Browser"
+
+if not venv_dir.exists():
+    print(f"Creating virtualenv in {venv_dir}")
+    EnvBuilder(with_pip=True).create(venv_dir)
+
+subprocess.run(
+    [
+        sys.executable,
+        "-m",
+        "pip",
+        "install",
+        "-r",
+        str(src_dir / "dev-requirements.txt"),
+    ]
+)
+subprocess.run(
+    [sys.executable, "-m", "pip", "install", "-r", str(src_dir / "requirements.txt")]
+)
+
+activate_script = (
+    "source .venv/bin/activate"
+    if sys.platform != "Windows"
+    else ".venv\Scripts\activate.bat"
+)
+print(f"Virtualenv `{venv_dir}` is ready and up-to-date.")
+print(f"Run `{activate_script}` to activate the virtualenv.")