Merge pull request #2203 from coasys/library-use-case

Don’t include unbound variables in results returned from run_query()

src/machine/lib_machine.rs

@@ -196,7 +196,12 @@ impl Machine {
                 let output: String = outputter.result();
                 // println!("Result: {} = {}", var_key.to_string(), output);
 
-                bindings.insert(var_key.to_string(), Value::try_from(output).expect("asdfs"));
+                if var_key.to_string() != output {
+                    bindings.insert(
+                        var_key.to_string(),
+                        Value::try_from(output).expect("Couldn't convert Houtput to Value"),
+                    );
+                }
             }
 
             matches.push(QueryResolutionLine::Match(bindings));
@@ -338,6 +343,21 @@ mod tests {
         );
     }
 
+    #[test]
+    fn empty_predicate() {
+        let mut machine = Machine::new_lib();
+        machine.load_module_string(
+            "facts",
+            r#"
+                :- discontiguous(subject_class/2).
+            "#
+            .to_string(),
+        );
+
+        let result = machine.run_query(String::from("subject_class(X, _)."));
+        assert_eq!(result, Ok(QueryResolution::False));
+    }
+
     #[test]
     fn list_results() {
         let mut machine = Machine::new_lib();
@@ -425,7 +445,7 @@ mod tests {
     }
 
     #[test]
-    fn stress_integration_test() {
+    fn integration_test() {
         let mut machine = Machine::new_lib();
 
         // File with test commands, i.e. program code to consult and queries to run
@@ -486,14 +506,12 @@ mod tests {
             output,
             Ok(QueryResolution::Matches(vec![QueryMatch::from(
                 btreemap! {
-                    "Predicate" => Value::from("Predicate"),
                     "Result" => Value::List(
                         Vec::from([
                             Value::List([Value::from("p1"), Value::from("b")].into()),
                             Value::List([Value::from("p2"), Value::from("b")].into()),
                         ])
                     ),
-                    "Target" => Value::from("Target"),
                 }
             ),]))
         );

src/machine/parsed_results.rs

@@ -65,11 +65,11 @@ impl From<Vec<QueryResolutionLine>> for QueryResolution {
             }
         }
 
-        // If there is only one line, and it is an empty match, return true.
+        // If there is only one line, and it is an empty match, return false.
         if query_result_lines.len() == 1 {
             if let QueryResolutionLine::Match(m) = query_result_lines[0].clone() {
                 if m.is_empty() {
-                    return QueryResolution::True;
+                    return QueryResolution::False;
                 }
             }
         }