Bazel: Pass current host java runtime to sh_test rule

Change-Id: I5f41dc1d8c46160b6870a53544293c44531adc81

prologtests/examples/BUILD

@@ -1,15 +1,12 @@
 package(default_visibility = ["//visibility:public"])
 
-DUMMY = ["dummy.sh"]
-
-# Enable prologtests on newer Java versions again, when this Bazel bug is fixed:
-# https://github.com/bazelbuild/bazel/issues/9391
 sh_test(
     name = "test_examples",
-    srcs = select({
-        "//:java11": DUMMY,
-        "//:java_next": DUMMY,
-        "//conditions:default": ["run.sh"],
-    }),
-    data = glob(["*.pl"]) + ["//:gerrit.war"],
+    srcs = ["run.sh"],
+    args = ["$(JAVA)"],
+    data = glob(["*.pl"]) + [
+        "//:gerrit.war",
+        "@bazel_tools//tools/jdk:current_host_java_runtime",
+    ],
+    toolchains = ["@bazel_tools//tools/jdk:current_host_java_runtime"],
 )

prologtests/examples/run.sh

@@ -1,5 +1,14 @@
 #!/bin/bash
 
+# TODO(davido): Figure out what to do if running alone and not invoked from bazel
+# $1 is equal to the $(JAVABASE)/bin/java make variable
+JAVA=$1
+
+# Checks whether or not the $1 is starting with a slash: '/' and thus considered to be
+# an absolute path. If it is, then it is left as is, if it isn't then "$PWD/ is prepended
+# (in sh_test case it is relative and thus the runfiles directory is prepended).
+[[ "$JAVA" =~ ^(/|[^/]+$) ]] || JAVA="$PWD/$JAVA"
+
 TESTS="t1 t2 t3"
 
 # Note that both t1.pl and t2.pl test code in rules.pl.
@@ -36,7 +45,7 @@ do
   # Unit tests do not need to define clauses in packages.
   # Use one prolog-shell per unit test, to avoid name collision.
   echo "### Running test ${T}.pl"
-  echo "[$T]." | java -jar ${GERRIT_WAR} prolog-shell -q -s load.pl
+  echo "[$T]." | "${JAVA}" -jar ${GERRIT_WAR} prolog-shell -q -s load.pl
 
   if [ "x$?" != "x0" ]; then
     echo "### Test ${T}.pl failed."