Split setup-virtualenv.sh into a few pieces

Some of the pieces may be usable in Docker image creation

.circleci/config.yml

@@ -86,14 +86,15 @@ jobs:
           command: |
             ~/project/.circleci/bootstrap-test-environment.sh ~/project
 
-
       - run: &SETUP_VIRTUALENV
           name: "Setup virtualenv"
           # pip cannot install packages if the working directory is not
           # readable.
           working_directory: "/tmp"
           command: |
-            /tmp/project/.circleci/setup-virtualenv.sh \
+            sudo --set-home -u nobody /tmp/project/.circleci/create-virtualenv.sh "${WHEELHOUSE_PATH}" "/tmp/tests"
+            sudo --set-home -u nobody /tmp/project/.circleci/populate-wheelhouse.sh "${WHEELHOUSE_PATH}" "/tmp/tests" "/tmp/project"
+            sudo --set-home -u nobody /tmp/project/.circleci/setup-virtualenv.sh \
                 "${TAHOE_LAFS_TOX_ENVIRONMENT}" \
                 "${TAHOE_LAFS_TOX_ARGS}"
 

.circleci/create-virtualenv.sh

@@ -0,0 +1,34 @@
+#!/bin/bash -eo pipefail
+
+# The filesystem location of the wheelhouse which we'll populate with wheels
+# for all of our dependencies.
+WHEELHOUSE_PATH="$1"
+shift
+
+# The filesystem location of the root of a virtualenv we can use to get/build
+# wheels.
+BOOTSTRAP_VENV="$1"
+shift
+
+# Set up the virtualenv as a non-root user so we can run the test suite as a
+# non-root user.  See below.
+virtualenv --python python2.7 "${BOOTSTRAP_VENV}"
+
+# For convenience.
+PIP="${BOOTSTRAP_VENV}/bin/pip"
+
+# Tell pip where it can find any existing wheels.
+export PIP_FIND_LINKS="file://${WHEELHOUSE_PATH}"
+
+# Get "certifi" to avoid bug #2913. Basically if a `setup_requires=...` causes
+# a package to be installed (with setuptools) then it'll fail on certain
+# platforms (travis's OX-X 10.12, Slackware 14.2) because PyPI's TLS
+# requirements (TLS >= 1.2) are incompatible with the old TLS clients
+# available to those systems.  Installing it ahead of time (with pip) avoids
+# this problem.  Make sure this step comes before any other attempts to
+# install things using pip!
+"${PIP}" install certifi
+
+# Get a new, awesome version of pip and setuptools.  For example, the
+# distro-packaged virtualenv's pip may not know about wheels.
+"${PIP}" install --upgrade pip setuptools wheel

.circleci/populate-wheelhouse.sh

@@ -0,0 +1,44 @@
+#!/bin/bash -eo pipefail
+
+# Python packages we need to support the test infrastructure.  *Not* packages
+# Tahoe-LAFS itself (implementation or test suite) need.
+TEST_DEPS="tox codecov"
+
+# Python packages we need to generate test reports for CI infrastructure.
+# *Not* packages Tahoe-LAFS itself (implement or test suite) need.
+REPORTING_DEPS="python-subunit junitxml subunitreporter"
+
+# The filesystem location of the wheelhouse which we'll populate with wheels
+# for all of our dependencies.
+WHEELHOUSE_PATH="$1"
+shift
+
+# The filesystem location of the root of a virtualenv we can use to get/build
+# wheels.
+BOOTSTRAP_VENV="$1"
+shift
+
+# The filesystem location of the root of the project source.  We need this to
+# know what wheels to get/build, of course.
+PROJECT_ROOT="$1"
+shift
+
+# For convenience.
+PIP="${BOOTSTRAP_VENV}/bin/pip"
+
+# Tell pip where it can find any existing wheels.
+export PIP_FIND_LINKS="file://${WHEELHOUSE_PATH}"
+
+# Populate the wheelhouse, if necessary.
+"${PIP}" \
+    wheel \
+    --wheel-dir "${WHEELHOUSE_PATH}" \
+    "${PROJECT_ROOT}" \
+    ${TEST_DEPS} \
+    ${REPORTING_DEPS}
+
+# Not strictly wheelhouse population but ...
+"${PIP}" \
+    install \
+    ${TEST_DEPS} \
+    ${REPORTING_DEPS}

.circleci/setup-virtualenv.sh

@@ -6,56 +6,8 @@ shift
 TAHOE_LAFS_TOX_ARGS=$1
 shift || :
 
-# Python packages we need to support the test infrastructure.  *Not* packages
-# Tahoe-LAFS itself (implementation or test suite) need.
-TEST_DEPS="tox codecov"
-
-# Python packages we need to generate test reports for CI infrastructure.
-# *Not* packages Tahoe-LAFS itself (implement or test suite) need.
-REPORTING_DEPS="python-subunit junitxml subunitreporter"
-
-# Make sure the ownership of the pip cache directory is correct.  The CircleCI
-# cache management operations seem to mess it up.  The cache directory might
-# not exist if there was no matching cache to restore.
-[ -e /tmp/nobody/.cache ] && chown --recursive nobody /tmp/nobody/.cache
-
-# Set up the virtualenv as a non-root user so we can run the test suite as a
-# non-root user.  See below.
-sudo --set-home -u nobody virtualenv --python python2.7 /tmp/tests
-
-# Get "certifi" to avoid bug #2913. Basically if a `setup_requires=...` causes
-# a package to be installed (with setuptools) then it'll fail on certain
-# platforms (travis's OX-X 10.12, Slackware 14.2) because PyPI's TLS
-# requirements (TLS >= 1.2) are incompatible with the old TLS clients
-# available to those systems.  Installing it ahead of time (with pip) avoids
-# this problem.  Make sure this step comes before any other attempts to
-# install things using pip!
-sudo --set-home -u nobody \
-     PIP_FIND_LINKS="${PIP_FIND_LINKS}" \
-     /tmp/tests/bin/pip install certifi
-
-# Get a new, awesome version of pip and setuptools.  For example, the
-# distro-packaged virtualenv's pip may not know about wheels.
-sudo --set-home -u nobody \
-     PIP_FIND_LINKS="${PIP_FIND_LINKS}" \
-     /tmp/tests/bin/pip install --upgrade pip setuptools wheel
-
-# Populate the wheelhouse, if necessary.
-sudo --set-home -u nobody \
-     PIP_FIND_LINKS="${PIP_FIND_LINKS}" \
-     /tmp/tests/bin/pip \
-     wheel \
-     --wheel-dir "${WHEELHOUSE_PATH}" \
-     /tmp/project ${TEST_DEPS} ${REPORTING_DEPS}
-
-sudo --set-home -u nobody \
-     PIP_FIND_LINKS="${PIP_FIND_LINKS}" \
-     /tmp/tests/bin/pip install ${TEST_DEPS} ${REPORTING_DEPS}
-
 # Get everything else installed in it, too.
-sudo --set-home -u nobody \
-     PIP_FIND_LINKS="${PIP_FIND_LINKS}" \
-     /tmp/tests/bin/tox \
+/tmp/tests/bin/tox \
      -c /tmp/project/tox.ini \
      --workdir /tmp/tahoe-lafs.tox \
      --notest \