Check that the node has a parent before matching a 'child' selector (#…

…138)

Co-authored-by: Michael Ficarra <github@michael.ficarra.me>

esquery.js

@@ -189,7 +189,7 @@ function generateMatcher(selector) {
             const left = getMatcher(selector.left);
             const right = getMatcher(selector.right);
             return (node, ancestry, options) => {
-                if (right(node, ancestry, options)) {
+                if (ancestry.length > 0 && right(node, ancestry, options)) {
                     return left(ancestry[0], ancestry.slice(1), options);
                 }
                 return false;

tests/queryComplex.js

@@ -38,4 +38,10 @@ describe('Complex selector query', function () {
             simpleProgram.body[2]
         ]);
     });
+
+    it('can not match a top level node', function () {
+        // Test fix for issue #135: half of a child selector matches a top-level node.
+        const matches = esquery(simpleProgram, 'NonExistingNodeType > *');
+        assert.isEmpty(matches);
+    });
 });