eclass/tests: Fail the .%.sh.ok Makefile recipe if the test fails

With .ONESHELL active, only the return status of the final recipe line
will be checked.

Signed-off-by: Ulrich Müller <ulm@gentoo.org>

eclass/tests/Makefile

@@ -2,18 +2,20 @@ SH_FILES := $(wildcard *.sh)
 TEST_FILES := $(filter-out tests-common.sh version-funcs.sh, $(SH_FILES))
 TEST_OK_FILES := $(patsubst %.sh, .%.sh.ok,$ $(TEST_FILES))
 
+# !!! _All_ recipe lines for each target will be provided to a single
+# !!! invocation of the shell.
+.ONESHELL:
+
 # We cache a successful test result if the testfile itself did not
 # change (%.sh) and the contents of the eclass/ directory did not
 # change (.eclasssum).
 .%.sh.ok: %.sh .eclasssum
-	./$<
-	touch $@
+	./$< && touch $@
 
 .PHONY: test
 test: $(TEST_OK_FILES)
 
 .PHONY: force
-.ONESHELL:
 .eclasssum: SHELL = /bin/bash
 .eclasssum: force
 	set -euo pipefail