Files
ThothII/frontend/src/components/ErrorBoundary.test.tsx
T
marcopanandClaude Fable 5 2f68b0d109 fix(frontend): contain viewer/widget crashes with error boundaries
A render error in one viewer or gate widget unmounted the whole React root
(white screen). Add a reusable ErrorBoundary (class component, no new dep) with
resetKeys + an on-brand fallback, and wire it at two surfaces:
- WidgetHost: isolates the gate widget (reset on descriptor id) so a malformed
  gate payload no longer blanks the conversation
- SessionDocumentsPanel: wraps each document (reset on doc key/content) so one
  crashing viewer degrades only its section; siblings and the panel survive

The observed crash: a schema-linking doc that parses but lacks `candidates`
makes SchemaLinkingViewer throw. Verified live via Playwright against the mock
backend. TDD throughout; tsc clean, 123/123 vitest (+8 new tests).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-05 13:18:51 +02:00

102 lines
3.3 KiB
TypeScript

import { render, screen } from "@testing-library/react";
import userEvent from "@testing-library/user-event";
import { useState } from "react";
import { ErrorBoundary } from "./ErrorBoundary";
/** A child that throws on demand. Toggle `boom` to control whether it crashes. */
function Boom({ boom, label = "kaboom" }: { boom: boolean; label?: string }) {
if (boom) throw new Error(label);
return <div>child ok</div>;
}
// React logs caught render errors to console.error; silence it so the suite output
// stays readable while still exercising the real error path.
let errorSpy: ReturnType<typeof vi.spyOn>;
beforeEach(() => {
errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
});
afterEach(() => {
errorSpy.mockRestore();
});
test("renders children when nothing throws", () => {
render(
<ErrorBoundary>
<Boom boom={false} />
</ErrorBoundary>,
);
expect(screen.getByText("child ok")).toBeInTheDocument();
});
test("renders the default fallback when a child throws", () => {
render(
<ErrorBoundary label="step">
<Boom boom />
</ErrorBoundary>,
);
expect(screen.queryByText("child ok")).not.toBeInTheDocument();
// Default fallback names the labelled surface.
expect(screen.getByText(/couldn't be displayed/i)).toBeInTheDocument();
expect(screen.getByText(/step/i)).toBeInTheDocument();
});
test("uses a custom fallback render prop with the error", () => {
render(
<ErrorBoundary fallback={(err) => <p>custom: {err.message}</p>}>
<Boom boom label="explode" />
</ErrorBoundary>,
);
expect(screen.getByText("custom: explode")).toBeInTheDocument();
});
test("calls onError when a child throws", () => {
const onError = vi.fn();
render(
<ErrorBoundary onError={onError}>
<Boom boom label="reported" />
</ErrorBoundary>,
);
expect(onError).toHaveBeenCalledTimes(1);
expect(onError.mock.calls[0][0]).toBeInstanceOf(Error);
expect((onError.mock.calls[0][0] as Error).message).toBe("reported");
});
test("recovers when resetKeys change to non-crashing content", async () => {
function Harness() {
const [boom, setBoom] = useState(true);
return (
<>
<button onClick={() => setBoom(false)}>fix</button>
<ErrorBoundary resetKeys={[boom]}>
<Boom boom={boom} />
</ErrorBoundary>
</>
);
}
render(<Harness />);
// Starts crashed → fallback visible.
expect(screen.getByText(/couldn't be displayed/i)).toBeInTheDocument();
// Flip the data (and thus resetKeys); the boundary clears and re-renders children.
await userEvent.click(screen.getByRole("button", { name: "fix" }));
expect(screen.getByText("child ok")).toBeInTheDocument();
expect(screen.queryByText(/couldn't be displayed/i)).not.toBeInTheDocument();
});
test("Try again resets the boundary", async () => {
let boom = true;
function Flaky() {
if (boom) throw new Error("transient");
return <div>recovered</div>;
}
render(
<ErrorBoundary>
<Flaky />
</ErrorBoundary>,
);
expect(screen.getByText(/couldn't be displayed/i)).toBeInTheDocument();
// Simulate the underlying condition clearing, then retry.
boom = false;
await userEvent.click(screen.getByRole("button", { name: /try again/i }));
expect(screen.getByText("recovered")).toBeInTheDocument();
});