BNF tests along with few BNF fixes

src/main/grammar/Rego.bnf

@@ -69,7 +69,7 @@ package         ::= "package" ref
 import          ::= "import" ref ( "as" var )?
 policy          ::=  rule*
 rule            ::=  "default"?  rule-head  rule-body*
-rule-head       ::= var ( "(" rule-args ")" )? ("[" term "]" )? ( ( ":=" | "=" ) term )?
+rule-head       ::= var ( "(" rule-args? ")" )? ("[" term "]" )? ( ( ":=" | "=" ) term )?
 rule-args       ::= term ( "," term )*
 rule-body       ::= ( else ( "=" term )? )? "{" query "}"
 query           ::=( literal |';' )+
@@ -86,7 +86,7 @@ set-compr       ::= "{" term "|" query "}"
 object-compr    ::= "{" object-item "|" query "}"
 infix-operator  ::= bool-operator | arith-operator | bin-operator
 bool-operator   ::= "==" | "!=" | "<" | ">" | ">=" | "<="
-arith-operator  ::= "+" | "-" | "*" | "/"
+arith-operator  ::= "+" | "-" | "*" | "/" | "%"
 bin-operator    ::= "&" | "|"
 ref             ::= ( expr-call  | array | object | set | array-compr | object-compr | set-compr |var  )  ref-arg*
 ref-arg         ::= ref-arg-dot | ref-arg-brack

src/test/kotlin/org/openpolicyagent/ideaplugin/lang/RegoParsingTestCase.kt

@@ -13,6 +13,8 @@ class RegoParsingTestCase: RegoParsingTestCaseBase() {
 
     fun `test array comprehension`() = doTestNoError()
     fun `test set comprehension`() = doTestNoError()
+    fun `test set comprehensions 2`() = doTestNoError()
+    fun `test set comprehensions 3`() = doTestNoError()
     fun `test object comprehension`() = doTestNoError()
 
     fun `test implicit or`() = doTestNoError()
@@ -25,4 +27,26 @@ class RegoParsingTestCase: RegoParsingTestCaseBase() {
     fun `test complex rule 2`() = doTestNoError()
     fun `test complex rule 3`() = doTestNoError()
 
-}
+
+    fun `test array comprehensions 2`() = doTestNoError()
+    fun `test built in functions`() = doTestNoError()
+    fun `test functions`() = doTestNoError()
+    fun `test multiple expressions`() = doTestNoError()
+    fun `test rules`() = doTestNoError()
+    fun `test self joins`() = doTestNoError()
+    fun `test with keyword 2`() = doTestNoError()
+
+
+    fun `test composite keys`() = doTestNoError()
+    fun `test composite values`() = doTestNoError()
+    fun `test else keyword 2`() = doTestNoError()
+    fun `test imports`() = doTestNoError()
+    fun `test negations`() = doTestNoError()
+    fun `test package with simple rule`() = doTestNoError()
+    fun `test references`() = doTestNoError()
+    fun `test rules with single predicates`() = doTestNoError()
+    fun `test scalars assignment`() = doTestNoError()
+    fun `test sets`() = doTestNoError()
+    fun `test strings`() = doTestNoError()
+    fun `test variables`() = doTestNoError()
+}

src/test/resources/org/openpolicyagent/ideaplugin/lang/parser/fixtures/array_comprehensions_2.rego

@@ -0,0 +1,17 @@
+package test
+
+apps:={}
+sites:={}
+
+app_to_hostnames[app_name] = hostnames {
+    app := apps[_]
+    app_name := app.name
+    hostnames := [hostname | name := app.servers[_]
+                            s := sites[_].servers[_]
+                            s.name == name
+                            hostname := s.hostname]
+}
+
+aRule {
+    app_to_hostnames[app]
+}