feat(validate): added isValidatorApplied util

Author: tlouisse

packages/validate/src/isValidatorApplied.js

@@ -0,0 +1,18 @@
+/**
+ * TODO: refactor validators to classes, putting needed meta info on instance.
+ * Note that direct function comparison (Validator[0] === minDate) doesn't work when code
+ * is transpiled
+ * @param {String} name - a name like minDate, maxDate, minMaxDate
+ * @param {Function} fn - the validator function to execute provided in [fn, param, config]
+ * @param {Function} requiredSignature - arguments needed to execute fn without failing
+ * @returns {Boolean} - whether the validator (name) is applied
+ */
+export function isValidatorApplied(name, fn, requiredSignature) {
+  let result;
+  try {
+    result = Object.keys(fn(new Date(), requiredSignature))[0] === name;
+  } catch (e) {
+    result = false;
+  }
+  return result;
+}

packages/validate/test/isValidatorApplied.test.js

@@ -0,0 +1,15 @@
+import { expect } from '@open-wc/testing';
+import { isValidatorApplied } from '../src/isValidatorApplied.js';
+
+describe('isValidatorApplied', () => {
+  it(`checks if validator (provided name string) is applied`, async () => {
+    const myValFn = (val, param) => ({ myValFn: param === 'x' });
+    const myOtherValFn = (val, param) => ({ myOtherValFn: param === 'x' });
+
+    expect(isValidatorApplied('myValFn', myValFn, 'x')).to.equal(true);
+    expect(isValidatorApplied('myValFn', myValFn, 'y')).to.equal(true);
+
+    expect(isValidatorApplied('myValFn', myOtherValFn, 'x')).to.equal(false);
+    expect(isValidatorApplied('myValFn', myOtherValFn, 'y')).to.equal(false);
+  });
+});