add tests for json formatter

tests/formatters/json_formatter.test.ts

@@ -0,0 +1,28 @@
+import { FormatterFactory } from "../../lib/formatters/formatter_factory";
+import { TestObject } from "./test_object";
+
+const formatter = FormatterFactory.getFormatter("json");
+
+test('test header', () => {
+  const object = [TestObject.testObject(), TestObject.testObject()];
+  expect(formatter.header(object)).toBe("[");
+});
+
+test('test footer', () => {
+  expect(formatter.footer()).toBe("]\n");
+});
+
+test('test convert', () => {
+  const object = [TestObject.testObject()];
+  const json = TestObject.asJson();
+
+  expect(formatter.convert(object, true)).toBe(json);
+  expect(formatter.convert(object, false)).toBe(`,${json}`);
+});
+
+test('test format with fasta', () => {
+  //const fasta = [['>test', '5']];
+  //const object = [TestObject.testObject()];
+  //const json = '{"fasta_header":">test","integer":5,"string":"string","list":["a",2,false]}';
+  //expect(formatter.format(object, fasta, true)).toBe(json);
+});