travis: Enable pytest-test-groups to split tests across several runs

Adds two new environment variables TEST_GROUP_COUNT and TEST_GROUP to
split the integration tests into groups and run only a selected group.

This allows us to increase the TEST_GROUP_COUNT and add a new
TEST_GROUP to avoid bumping up against the time limit when running in
valgrind.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

.travis.yml

@@ -8,9 +8,11 @@ notifications:
 env:
   - NO_VALGRIND=1 ARCH=32 DEVELOPER=1 COMPILER=gcc
   - NO_VALGRIND=1 ARCH=64 DEVELOPER=1 COMPILER=gcc
-  - NO_VALGRIND=0 ARCH=64 DEVELOPER=1 COMPILER=gcc
   - NO_VALGRIND=0 ARCH=64 DEVELOPER=0 COMPILER=gcc
   - NO_VALGRIND=1 ARCH=64 DEVELOPER=1 COMPILER=clang
+  - NO_VALGRIND=0 ARCH=64 DEVELOPER=1 COMPILER=gcc TEST_GROUP=1 TEST_GROUP_COUNT=3
+  - NO_VALGRIND=0 ARCH=64 DEVELOPER=1 COMPILER=gcc TEST_GROUP=2 TEST_GROUP_COUNT=3
+  - NO_VALGRIND=0 ARCH=64 DEVELOPER=1 COMPILER=gcc TEST_GROUP=3 TEST_GROUP_COUNT=3
 
 # Trusty (aka 14.04) is way way too old, so run in docker...
 script:

Makefile

@@ -169,6 +169,11 @@ include devtools/Makefile
 # Git doesn't maintain timestamps, so we only regen if git says we should.
 CHANGED_FROM_GIT = [ x"`git log $@ | head -n1`" != x"`git log $< | head -n1`" -o x"`git diff $<`" != x"" ]
 
+ifeq ($(TEST_GROUP_COUNT),)
+TEST_GROUP=1
+TEST_GROUP_COUNT=1
+endif
+
 check:
 	$(MAKE) pytest
 
@@ -176,7 +181,7 @@ pytest: $(ALL_PROGRAMS)
 ifndef PYTEST
 	PYTHONPATH=contrib/pylightning DEVELOPER=$(DEVELOPER) python3 tests/test_lightningd.py -f
 else
-	PYTHONPATH=contrib/pylightning TEST_DEBUG=1 DEVELOPER=$(DEVELOPER) $(PYTEST) -vx tests/test_lightningd.py
+	PYTHONPATH=contrib/pylightning TEST_DEBUG=1 DEVELOPER=$(DEVELOPER) $(PYTEST) -vx tests/test_lightningd.py --test-group=$(TEST_GROUP) --test-group-count=$(TEST_GROUP_COUNT)
 endif
 
 # Keep includes in alpha order.