Update installation instructions and run the installation test unconditionally

The installation instructions were based on running `setup.py` directly.
However, my understanding is that Python best practices have moved away
from doing that and towards using `pip` to install packages in a virtual
environment, and using a file like `requirements.txt` to pin dependency
versions.

This patch documents that updated installation procedure and runs the
installation process as a test unconditionally.

Fixes #68

Author: ldionne

docs/developer_guide.rst

@@ -10,8 +10,8 @@ started.
 Installation
 ------------
 
-See :ref:`quickstart` for setting up an installation. Use the "develop" option
-when running ~/lnt/setup.py.
+See :ref:`quickstart` for setting up an installation. Pass ``-e`` to ``pip`` when
+installing the package to install it in "editable" mode.
 
 Running LNT's Regression Tests
 ------------------------------

docs/quickstart.rst

@@ -12,35 +12,20 @@ Installation
 The first thing to do is to checkout install the LNT software itself. The
 following steps should suffice on any modern Unix variant:
 
-#. Install ``virtualenv``, if necessary::
-
-           sudo easy_install virtualenv
-
-   ``virtualenv`` is a standard Python tool for allowing the installation of
-   Python applications into their own sandboxes, or virtual environments.
-
-#. Create a new virtual environment for the LNT application::
-
-            virtualenv ~/mysandbox
-
-   This will create a new virtual environment at ``~/mysandbox``.
-
 #. Checkout the LNT sources::
 
             git clone https://github.com/llvm/llvm-lnt.git ~/lnt
 
-#. Install LNT into the virtual environment::
+#. Create a new virtual environment for the LNT application and activate it::
 
-           ~/mysandbox/bin/python ~/lnt/setup.py develop
+            python3 -m venv .venv
+            source .venv/bin/activate
+
+#. Install LNT into the virtual environment::
 
-   We recommend using ``develop`` instead of install for local use, so that any
-   changes to the LNT sources are immediately propagated to your
-   installation. If you are running a production install or care a lot about
-   stability, you can use ``install`` which will copy in the sources and you
-   will need to explicitly re-install when you wish to update the LNT
-   application.
+            pip install -r requirements.txt
 
-That's it!
+That's it! ``lnt`` should now be accessible from the virtual environment.
 
 
 Running Tests

lnt/lnttool/main.py

@@ -475,8 +475,7 @@ def _version_check():
         installed = "{} {}".format(meta['Name'], meta['Version'])
         current = "{} {}".format(lnt.__name__, lnt.__version__)
         raise SystemExit(f"""\
-error: installed distribution {installed} is not current ({current}), you may need to reinstall
-LNT or rerun 'setup.py develop' if using development mode.""")
+error: installed distribution {installed} is not current ({current}), you may need to reinstall LNT""")
 
 
 def show_version(ctx, param, value):

setup.py

@@ -14,12 +14,6 @@
     os.environ["CXX"] = "xcrun --sdk macosx clang"
     cflags += ['-stdlib=libc++', '-mmacosx-version-min=10.7']
 
-# setuptools expects to be invoked from within the directory of setup.py, but
-# it is nice to allow:
-#   python path/to/setup.py install
-# to work (for scripts, etc.)
-os.chdir(os.path.dirname(os.path.abspath(__file__)))
-
 cPerf = Extension('lnt.testing.profile.cPerf',
                   sources=['lnt/testing/profile/cPerf.cpp'],
                   extra_compile_args=['-std=c++11'] + cflags)

tests/utils/Installation.py

@@ -2,11 +2,8 @@
 # we didn't install package data properly).
 #
 # RUN: rm -rf %t.venv
-# RUN: virtualenv %t.venv
-# RUN: %t.venv/bin/python %{src_root}/setup.py install
+# RUN: python -m venv %t.venv
+# RUN: cd %{src_root}
+# RUN: %t.venv/bin/python -m pip install -r requirements.txt
 # RUN: rm -rf %t.installation
 # RUN: %t.venv/bin/lnt create %t.installation
-#
-# Disable this test by default, it is very slow because it does a full install.
-#
-# REQUIRES: long