test: add welcome page test

__tests__/welcome.test.tsx

@@ -0,0 +1,9 @@
+import React from "react"
+import { render } from "@testing-library/react-native"
+import WelcomeScreen from "../app/index"
+
+test("renders welcome page text", () => {
+  const { getByText } = render(<WelcomeScreen />)
+  const welcomeText = getByText("Seja bem-vindo(a) ao Osiris!")
+  expect(welcomeText).toBeTruthy()
+})