Add test case for new option -json-compilation-database

Makefile

@@ -1256,6 +1256,10 @@ $(LONELY_TESTS_DYN_FILES): OFLAGS+=$(TEST_DIRS_AS_PLUGIN:%=-I tests/%)
 # Tests directories without .ml but that must be tested anyway
 PLUGIN_TESTS_LIST += cil
 
+ifeq ("$(HAS_YOJSON)","yes")
+PLUGIN_TESTS_LIST += jcdb
+endif
+
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 # Emacs tags #
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tests/jcdb/compile_commands.json

+[
+  { "directory": "tests/jcdb",
+    "command": "/usr/bin/clang++ -DTEST=42",
+    "file": "jcdb.c"
+  }
+]

tests/jcdb/jcdb.c

+/* run.config
+OPT: -json-compilation-database @PTEST_DIR@ -print
+*/
+
+int main () { return TEST; }

tests/jcdb/oracle/jcdb.res.oracle

+[kernel] Parsing tests/jcdb/jcdb.c (with preprocessing)
+/* Generated by Frama-C */
+int main(void)
+{
+  int __retres;
+  __retres = 42;
+  return __retres;
+}
+
+