Initial test framework and first test.

Add a basic test framework, borrowed from the framework used
by git.git.  A shell script library (tests/test-lib.sh) helps
generate the fixtures, and simplifies the process of writing
test scripts.  Tests can be run as a suite (via 'make test')
or individually (sh tests/t0000-config.sh).  Results are aggregated
upon completion.  Includes a detailed README.

A basic test of config file processing is part of this commit.

Signed-off-by: Emil Sit <sit@emilsit.net>

Makefile

@@ -29,6 +29,23 @@ dist: $(DISTFILES) todo.sh
 clean:
 	rm -f $(DISTNAME).tar.gz $(DISTNAME).zip
 
-.PHONY: test
-test:
-	@echo "TBD!"
+#
+# Testing
+#
+TESTS = $(wildcard tests/t[0-9][0-9][0-9][0-9]-*.sh)
+#TEST_OPTIONS=--verbose
+
+test-pre-clean:
+	rm -rf tests/test-results "tests/trash directory"*
+
+aggregate-results: $(TESTS)
+
+$(TESTS): test-pre-clean
+	-cd tests && sh $(notdir $@) $(TEST_OPTIONS)
+
+test: aggregate-results
+	tests/aggregate-results.sh tests/test-results/t*-*
+	rm -rf tests/test-results
+    
+# Force tests to get run every time
+.PHONY: test test-pre-clean aggregate-results $(TESTS)