Add visitor tests

Author: IvanGoncharov

src/language/__tests__/visitor-test.js

@@ -17,6 +17,35 @@ import { testSchema } from '../../validation/__tests__/harness';
 import { getNamedType, isCompositeType } from '../../type';
 
 describe('Visitor', () => {
+  it('check path argument', () => {
+    const visited = [];
+
+    const ast = parse('{ a }');
+    visit(ast, {
+      enter(node, key, parent, path) {
+        visited.push(['enter', path.slice()]);
+      },
+
+      leave(node, key, parent, path) {
+        visited.push(['leave', path.slice()]);
+      },
+    });
+
+    console.log(JSON.stringify(visited, null, 2));
+    expect(visited).to.deep.equal([
+      ['enter', []],
+      ['enter', ['definitions', 0]],
+      ['enter', ['definitions', 0, 'selectionSet']],
+      ['enter', ['definitions', 0, 'selectionSet', 'selections', 0]],
+      ['enter', ['definitions', 0, 'selectionSet', 'selections', 0, 'name']],
+      ['leave', ['definitions', 0, 'selectionSet', 'selections', 0]],
+      ['leave', ['definitions', 0, 'selectionSet', 'selections']],
+      ['leave', ['definitions', 0]],
+      ['leave', ['definitions']],
+      ['leave', []],
+    ]);
+  });
+
   it('allows editing a node both on enter and on leave', () => {
     const ast = parse('{ a, b, c { a, b, c } }', { noLocation: true });