refactor: walk and pathToString functions

package.json

@@ -7,7 +7,7 @@
   ],
   "scripts": {
     "lint": "eslint --ext ts src",
-    "test": "jest",
+    "test": "npm run build && jest",
     "build": "tsc",
     "coverage": "jest --coverage"
   },
@@ -38,14 +38,29 @@
     "@commitlint/config-conventional": "^11.0.0",
     "@typescript-eslint/eslint-plugin": "^4.4.0",
     "@typescript-eslint/parser": "^4.4.0",
+    "@types/jest": "^26.0.15",
     "eslint": "^6.8.0",
     "husky": "^4.2.3",
     "jest": "^26.0.1",
+    "ts-jest": "^26.4.1",
     "typescript": "^4.0.3"
   },
   "engines": {
     "node": ">= 12.0.0"
   },
+  "jest": {
+    "roots": [
+      "<rootDir>/tests",
+      "<rootDir>/regression-tests"
+    ],
+    "testMatch": [
+      "**/?(*.)+(spec|test).+(ts|tsx|js)"
+    ],
+    "transform": {
+      "^.+\\.(ts|tsx)$": "ts-jest"
+    },
+    "preset": "ts-jest"
+  },
   "husky": {
     "hooks": {
       "pre-commit": "npm run lint && npm test",

src/walk.ts

@@ -1,4 +1,9 @@
-export function walk(node, path, visitor, parent?) {
+export function walk(
+  node: any,
+  path: (string | number)[],
+  visitor: Function,
+  parent?: any
+) {
   if (typeof node === 'string' || typeof node === 'number') {
     visitor(node, path, parent);
   } else if (Array.isArray(node)) {
@@ -13,7 +18,10 @@ export function walk(node, path, visitor, parent?) {
   }
 }
 
-export function pathToString(path) {
+export function pathToString(path: (string | number)[]) {
+  if (!path) {
+    throw Error('Path should contain at least one subpath in it');
+  }
   let str = '';
   for (const segment of path) {
     if (typeof segment == 'number') {

tests/walk.test.ts

@@ -0,0 +1,39 @@
+import { pathToString, walk } from '../src/walk';
+
+describe.each([
+    [[], ''],
+    [['somepath'], '.somepath'],
+    [[1, 'path'], '.[1].path'],
+    [['some', 'path'], '.some.path'],
+    [['some', 'other', '2'], '.some.other.2'],
+    [['some', 'other', 2], '.some.other[2]'],
+    [['some', 'other', 2, 'suffix'], '.some.other[2].suffix'],
+    [['some', 'other', 2, 'suffix', 3, 'secondsuffix'], '.some.other[2].suffix[3].secondsuffix'],
+])('path stringifier: ', (originalPath, expectedStringified) => {
+    test(`${originalPath} should be ${expectedStringified}`, () => {
+        expect(pathToString(originalPath)).toBe(expectedStringified);
+    });
+});
+
+it('stringifying empty path should throw an error', () => {
+    expect(() => pathToString(null)).toThrowError()
+})
+
+describe.each([
+    [null, [], 0],
+    [2, [], 1],
+    ['two', [], 1],
+    [{ node: 'node' }, ['node'], 1],
+    [[], ['some', 'existsing', 'path'], 0],
+    [['existingElement'], [], 1],
+    [{ node: [] }, [], 0],
+    [['existingElement', 'anotherExistingElement'], [], 2],
+    [['existingElement', ['anotherExistingElement']], ['existing', 'path'], 2],
+    [['existingElement', ['anotherExistingElement']], [], 2],
+])('should work', (node, path, expectedVisitCalls) => {
+    test(`Node ${JSON.stringify(node)} with path: ${path} should be visited ${expectedVisitCalls} times`, () => {
+        const mockVisitorFn: jest.Mock<any, any> = jest.fn();
+        walk(node, path, mockVisitorFn);
+        expect(mockVisitorFn).toHaveBeenCalledTimes(expectedVisitCalls);
+    });
+});