Merge pull request #1769 from pjonsson/detect-failure

tests: ensure cd is successful

tests/Makefile.compile-test

@@ -39,7 +39,7 @@ get_target_vars = $(wordlist 2,15,$(subst :, ,$1))
 
 define dooneexample
 @echo -n Building example $(3): $(1) $(4) for target $(2)
-@((cd $(EXAMPLESDIR)/$(1); \
+@((cd $(EXAMPLESDIR)/$(1) && \
  $(MAKE) $(4) TARGET=$(2) clean && make -j $(4) TARGET=$(2) WERROR=1) > \
       /dev/null 2>make.err && \
  (echo " -> OK" && printf "%-75s %-40s %-20s TEST OK\n" "$(1)" "$(4)" "$(2)" > $(3)-$(subst /,-,$(1))$(2).testlog) || \
@@ -53,16 +53,23 @@ $(call dooneexample,$(dir $(call get_target,${1})),$(notdir $(call get_target,${
 endef
 #end of GNU make magic
 
-examples:
+examples: | $(EXAMPLESDIR)
 	$(foreach ex, $(EXAMPLES), $(call doexample, ${ex}))
 
+$(EXAMPLESDIR):
+	@echo "Could not find examples directory $(EXAMPLESDIR).\n"
+	@echo "If this failure is when running 19-out-of-tree-builds, clone"
+	@echo "https://github.com/contiki-ng/out-of-tree-tests into"
+	@echo "$(EXAMPLESDIR) and run the test again.\n"
+	@false
+
 summary: examples
 	@cat *.testlog > summary
 	@echo "========== Summary =========="
 	@cat summary
 
-clean:
+clean: | $(EXAMPLESDIR)
 	@rm -f *.testlog summary
 	@$(foreach example, $(EXAMPLES), \
            $(foreach target, $(EXAMPLESTARGETS), \
-             (cd $(EXAMPLESDIR)/$(example); $(MAKE) TARGET=$(target) clean);))
+             (cd $(EXAMPLESDIR)/$(example) && $(MAKE) TARGET=$(target) clean);))