add component tracking test (svelte testing library)

packages/svelte/test/performance.test.ts

@@ -0,0 +1,56 @@
+import { Scope } from '@sentry/hub';
+import { render } from '@testing-library/svelte';
+
+import DummyComponent from './components/Dummy.svelte';
+
+let testTransaction = {
+  startChild: jest.fn(),
+  finish: jest.fn(),
+};
+let testUpdateSpan = { finish: jest.fn() };
+let testInitSpan = { finish: jest.fn(), startChild: jest.fn(), transaction: testTransaction };
+
+jest.mock('@sentry/hub', () => {
+  const original = jest.requireActual('@sentry/hub');
+  return {
+    ...original,
+    getCurrentHub(): {
+      getScope(): Scope;
+    } {
+      return {
+        getScope(): any {
+          return {
+            getTransaction: () => {
+              return testTransaction;
+            },
+          };
+        },
+      };
+    },
+  };
+});
+
+describe('Sentry.trackComponent()', () => {
+  beforeEach(() => {
+    jest.resetAllMocks();
+
+    testTransaction.startChild.mockReturnValue(testInitSpan);
+    testInitSpan.startChild.mockReturnValue(testUpdateSpan);
+  });
+  it('creates nested init and update spans on component initialization', () => {
+    render(DummyComponent, { props: { options: {} } });
+
+    expect(testTransaction.startChild).toHaveBeenCalledWith({
+      description: '<Dummy>',
+      op: 'ui.svelte.init',
+    });
+
+    expect(testInitSpan.startChild as jest.Mock).toHaveBeenCalledWith({
+      description: '<Dummy>',
+      op: 'ui.svelte.update',
+    });
+
+    expect(testInitSpan.finish).toHaveBeenCalledTimes(1);
+    expect(testUpdateSpan.finish).toHaveBeenCalledTimes(1);
+  });
+});