bun-src/test/regression/issue/21680.test.ts

import { expect, test } from "bun:test";
import { tempDir } from "harness";

test("HTMLRewriter should not crash when element handler throws an exception - issue #21680", async () => {
  // The most important test: ensure the original crashing case from the GitHub issue doesn't crash
  // This was the exact case from the issue that caused "ASSERTION FAILED: Unexpected exception observed"

  // Create a minimal HTML file for testing
  using dir = tempDir("htmlrewriter-crash-test", {
    "min.html": "<script></script>",
  });

  // Original failing case: this should not crash the process
  const rewriter = new HTMLRewriter().on("script", {
    element(a) {
      throw new Error("abc");
    },
  });
  const res = rewriter.transform(new Response(Bun.file(`${dir}/min.html`)));
  // The important thing is it doesn't crash; the handler's error surfaces on
  // the output body. Await it so the file read completes before `dir` is
  // disposed.
  await expect(res.text()).rejects.toThrow("abc");

  // Test with Response containing string content. A `Response` input surfaces
  // the handler's error on the output body rather than throwing from
  // `transform()`; the point of this test is that neither crashes.
  const rewriter2 = new HTMLRewriter().on("script", {
    element(a) {
      throw new Error("response test");
    },
  });
  await expect(rewriter2.transform(new Response("<script></script>")).text()).rejects.toThrow("response test");
});

test("HTMLRewriter exception handling should not break normal operation", () => {
  // Ensure that after an exception occurs, the rewriter still works normally
  let normalCallCount = 0;

  // First, trigger an exception
  try {
    const rewriter = new HTMLRewriter().on("div", {
      element(element) {
        throw new Error("test error");
      },
    });
    rewriter.transform(new Response("<div>test</div>"));
  } catch (e) {
    // Expected to throw
  }

  // Then ensure normal operation still works
  const rewriter2 = new HTMLRewriter().on("div", {
    element(element) {
      normalCallCount++;
      element.setInnerContent("replaced");
    },
  });

  const result = rewriter2.transform(new Response("<div>original</div>"));
  expect(normalCallCount).toBe(1);
  // The transform should complete successfully without throwing
});