unit tests: add rule for running with test-tool

In the previous commit, we added support in test-tool for running
collections of unit tests. Now, add rules in t/Makefile for running in
this way.

This new rule can be executed from the top-level Makefile via
`make DEFAULT_UNIT_TEST_TARGET=unit-tests-test-tool unit-tests`, or by
setting DEFAULT_UNIT_TEST_TARGET in config.mak.

Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: steadmon

Makefile

@@ -3875,5 +3875,5 @@ $(UNIT_TEST_PROGS): $(UNIT_TEST_BIN)/%$X: $(UNIT_TEST_DIR)/%.o $(UNIT_TEST_DIR)/
 
 .PHONY: build-unit-tests unit-tests
 build-unit-tests: $(UNIT_TEST_PROGS)
-unit-tests: $(UNIT_TEST_PROGS)
+unit-tests: $(UNIT_TEST_PROGS) t/helper/test-tool$X
 	$(MAKE) -C t/ unit-tests

t/Makefile

@@ -49,6 +49,7 @@ CHAINLINT = '$(PERL_PATH_SQ)' chainlint.pl
 UNIT_TEST_SOURCES = $(wildcard unit-tests/t-*.c)
 UNIT_TEST_PROGRAMS = $(patsubst unit-tests/%.c,unit-tests/bin/%$(X),$(UNIT_TEST_SOURCES))
 UNIT_TESTS = $(sort $(UNIT_TEST_PROGRAMS))
+UNIT_TESTS_NO_DIR = $(notdir $(UNIT_TESTS))
 
 # `test-chainlint` (which is a dependency of `test-lint`, `test` and `prove`)
 # checks all tests in all scripts via a single invocation, so tell individual
@@ -76,14 +77,21 @@ $(T):
 $(UNIT_TESTS):
 	@echo "*** $@ ***"; $@
 
-.PHONY: unit-tests unit-tests-raw unit-tests-prove
+.PHONY: unit-tests unit-tests-raw unit-tests-prove unit-tests-test-tool
 unit-tests: $(DEFAULT_UNIT_TEST_TARGET)
 
 unit-tests-raw: $(UNIT_TESTS)
 
 unit-tests-prove:
 	@echo "*** prove - unit tests ***"; $(PROVE) $(GIT_PROVE_OPTS) $(UNIT_TESTS)
 
+unit-tests-test-tool:
+	@echo "*** test-tool - unit tests **"
+	( \
+		cd unit-tests/bin && \
+		../../helper/test-tool$X run-command testsuite $(UNIT_TESTS_NO_DIR)\
+	)
+
 pre-clean:
 	$(RM) -r '$(TEST_RESULTS_DIRECTORY_SQ)'