functional_tests: Allow provisioning VM for functional tests

It's now possible to run the tests in the VM more easily
without copy-pasting too much from HACKING.md.
`vagrant provision --provisiion-with tests` will take care of the dependencies.

freedombox/plinth#1521 - Provision VM to run function functional tests

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

HACKING.md

@@ -169,6 +169,9 @@ executed (red).
 
 ### Install Dependencies
 
+**For running tests in the VM** run `vagrant provision --provision-with tests`.
+Otherwise follow the instructions below.
+
 ```
 $ pip3 install splinter
 $ pip3 install pytest-splinter
@@ -209,7 +212,13 @@ tests will create the required user using FreedomBox's first boot process.
 
 ### Run Functional Tests
 
-Run
+**When inside a VM you will need to target the guest VM**
+
+```bash
+export FREEDOMBOX_URL=https://localhost
+```
+
+You will be running `py.test-3`. 
 
 ```
 $ py.test-3 --include-functional

Vagrantfile

@@ -44,6 +44,7 @@ Vagrant.configure(2) do |config|
     # Install ncurses-term
     DEBIAN_FRONTEND=noninteractive apt-get install -y ncurses-term
   SHELL
+  config.vm.provision "tests", run: "never", type: "shell", path: "functional_tests/install.sh"
   config.vm.post_up_message = "FreedomBox virtual machine is ready
 for development. You can run the development version of Plinth using
 the following command.

functional_tests/install.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+set -euo pipefail
+IFS=$'\n\t'
+
+echo "Installing requirements"
+sudo apt-get install -yq --no-install-recommends \
+    python3-pytest \
+    python3-pip firefox \
+    xvfb
+pip3 install splinter pytest-splinter pytest-bdd pytest-xvfb
+
+echo "Installing geckodriver"
+(
+    DL_DIR=/tmp/gecko
+    GECKO_VERSION="v0.24.0"
+    FILENAME="geckodriver-${GECKO_VERSION}-linux64.tar.gz"
+    GECKO_URL="https://github.com/mozilla/geckodriver/releases/download/$GECKO_VERSION/$FILENAME"
+
+    test -e /usr/local/bin/geckodriver &&  echo "geckodriver already installed" && exit 0
+
+    mkdir -p $DL_DIR
+    cd $DL_DIR
+    if ! [[ -e $FILENAME ]] ; then
+        wget --no-clobber \
+            --continue \
+            --no-verbose \
+            "$GECKO_URL"
+    fi
+    tar xf $FILENAME
+    sudo mv geckodriver /usr/local/bin/geckodriver
+    echo "Done"
+)