Add a Makefile to allow testing of the existing code.

A small makefile allows the invocation of the test modules, so that
we can exercise the system and make sure that it does sensible things
when it's run - or at least that it doesn't regress.

Makefile

@@ -0,0 +1,77 @@
+# Common User Targets:
+#
+#	make tests
+#		- Sxecute the tests
+#
+#	make shell
+#		- Set up the environment and drop to a shell (re-uses existing shells if they
+#		  have already been set up).
+#		  Use ctrl-d or `exit` to leave the shell.
+#
+#	PYTHON_TOOL=python2 make <target>
+#		- Build the target requested, using python 2
+#
+#
+# Assumptions:
+#	* Python 3 is installed as `python3`. Use the PYTHON_TOOL variable to test using a
+#	  specific python binary.
+#	* The 'virtualenv' tool is installed.
+#
+
+
+PYTHON_TOOL ?= python3
+ACTIVATE = source venv/${PYTHON_TOOL}/bin/activate
+
+.PHONY: tests venv
+
+TEST_MODULES = ${patsubst tests/%.py,%,$(wildcard tests/test_*.py)}
+
+ifeq (${NOCOLOUR},)
+COL_NOTICE = "\\e[35m"
+COL_GOOD = "\\e[32m"
+COL_RESET = "\\e[0m"
+else
+COL_NOTICE = ""
+COL_GOOD = ""
+COL_RESET = ""
+endif
+
+NOTICE = @notice() { printf "\n${COL_NOTICE}+++ %s${COL_RESET}\n" "$$@"; } && notice
+GOOD = @notice() { printf "\n${COL_GOOD}+++ %s${COL_RESET}\n" "$$@"; } && notice
+
+
+tests: test_testable
+	${NOTICE} "Running tests"
+	@# Note: We cd into the tests directory, so that we are testing the installed version, not
+	@# 		the version in the repository.
+	${ACTIVATE} && cd tests && python -munittest -v ${TEST_MODULES}
+	${GOOD} "Tests passed"
+
+venv: venv/successful-${PYTHON_TOOL}
+
+venv/successful-${PYTHON_TOOL}:
+	${NOTICE} "Build the virtualenv we will test within (for ${PYTHON_TOOL})"
+	-rm -rf venv
+	mkdir -p venv
+	virtualenv -p ${PYTHON_TOOL} venv/${PYTHON_TOOL}
+	touch venv/successful-${PYTHON_TOOL}
+
+test_installable: venv
+	${NOTICE} "Check that we can install the product"
+	${ACTIVATE} && python setup.py install
+
+test_testable: test_installable
+	${NOTICE} "Install the test requirements"
+	${ACTIVATE} && pip install -r requirements-test.txt
+
+clean:
+	${NOTICE} "Cleaning temporary files"
+	-rm -rf venv dist build
+	-find . -name '*.pyc' -delete
+	-find . -name '__pycache__' -delete
+	${GOOD} "Cleaned"
+
+shell: venv
+	${NOTICE} "Running shell; use ctrl-d or `exit` to leave"
+	bash -i <<<"${ACTIVATE} && exec < /dev/tty"
+	${GOOD} "Returned to user shell"