fix(validator): throw error if getMessage not of type Function

packages/validate/src/Validator.js

@@ -58,8 +58,14 @@ export class Validator {
       config: this.config,
       ...data,
     };
-    if (typeof this.config.getMessage === 'function') {
-      return this.config.getMessage(composedData);
+    if (this.config.getMessage) {
+      if (typeof this.config.getMessage === 'function') {
+        return this.config.getMessage(composedData);
+      }
+      throw new Error(
+        `You must provide a value for getMessage of type 'function', you provided a value of type: ${typeof this
+          .config.getMessage}`,
+      );
     }
     return this.constructor.getMessage(composedData);
   }

packages/validate/test/Validator.test.js

@@ -1,9 +1,22 @@
 import { expect, fixture, html, unsafeStatic, defineCE } from '@open-wc/testing';
-import { LitElement } from '@lion/core';
 import sinon from 'sinon';
+import { LitElement } from '@lion/core';
 import { ValidateMixin } from '../src/ValidateMixin.js';
 import { Validator } from '../src/Validator.js';
 
+async function expectThrowsAsync(method, errorMessage) {
+  let error = null;
+  try {
+    await method();
+  } catch (err) {
+    error = err;
+  }
+  expect(error).to.be.an('Error', 'No error was thrown');
+  if (errorMessage) {
+    expect(error.message).to.equal(errorMessage);
+  }
+}
+
 describe('Validator', () => {
   it('has an "execute" function returning "shown" state', async () => {
     class MyValidator extends Validator {
@@ -22,6 +35,20 @@ describe('Validator', () => {
     }).to.throw('You must provide a name like "this.name = \'IsCat\'" for your Validator');
   });
 
+  it('throws when executing a Validator that has a getMessage config property with a value not of type function', async () => {
+    class MyValidator extends Validator {
+      constructor(...args) {
+        super(...args);
+        this.name = 'MyValidator';
+      }
+    }
+
+    await expectThrowsAsync(
+      () => new MyValidator({}, { getMessage: 'This is the custom error message' })._getMessage(),
+      "You must provide a value for getMessage of type 'function', you provided a value of type: string",
+    );
+  });
+
   it('receives a "param" as a first argument on instantiation', async () => {
     const vali = new Validator('myParam');
     expect(vali.param).to.equal('myParam');