test: add tests for toDateString

src/helpers/to-date-string.ts

@@ -1,8 +1,3 @@
 export function toDateString(date: Date): string {
-  try {
-    const dateString = date.toJSON();
-    return dateString == null ? '' : dateString.replace(/^(.+)T.+/i, '$1');
-  } catch {
-    return '';
-  }
-}
+  return date.toISOString().replace(/^(.+)T.+/i, '$1');
+}

src/tests/helpers/to-date-string.test.ts

@@ -0,0 +1,13 @@
+import { expect } from '@open-wc/testing';
+
+import { toDateString } from '../../helpers/to-date-string';
+
+describe(toDateString.name, () => {
+  it('returns date string', () => {
+    const testDateStr = '2020-02-02';
+
+    const result = toDateString(new Date(testDateStr));
+
+    expect(result).equal(testDateStr);
+  });
+});