add some renderer tests

src/test/renderer-test.ts

@@ -0,0 +1,46 @@
+import {test} from 'node:test';
+import {Renderer, TextComponent} from '../renderer';
+import * as assert from 'node:assert/strict';
+import {interceptStdout} from './utils';
+import * as constants from '../constants';
+
+test('TextComponent', async (t) => {
+  const component = new TextComponent('lorem ipsum dolor');
+
+  await t.test('Instantiates with correct value', () => {
+    assert.equal(component.output(), 'lorem ipsum dolor');
+  });
+
+  await t.test('.setText behaves correctly', () => {
+    let onChangeCalled = false;
+    component.onChange = () => (onChangeCalled = true);
+    component.setText('sit amet');
+    assert.equal(component.output(), 'sit amet');
+    assert.ok(onChangeCalled);
+  });
+
+  await t.test('finish behaves correctly', () => {
+    let finishCallbackRuns = 0;
+    component.onFinish = () => finishCallbackRuns++;
+
+    component.finish();
+    component.finish();
+
+    assert.ok(component.finished);
+    assert.equal(finishCallbackRuns, 1);
+  });
+});
+
+function createRendererOutput(text: string) {
+  return constants.CLEAR_LINE + constants.HIDE_CURSOR + text + '\n';
+}
+
+test('Renderer', async (t) => {
+  await t.test('displays TextComponent', async () => {
+    const stdout = await interceptStdout(async () => {
+      const renderer = new Renderer();
+      renderer.addComponent(new TextComponent('lorem ipsum dolor'));
+    });
+    assert.equal(stdout, createRendererOutput('lorem ipsum dolor'));
+  });
+});