denoland/deno · error

Test failed

Error message

Test failed

What it means

Generic terminal error returned by the Deno LSP test runner when the run summary has at least one failure (summary.failed > 0). failed is incremented by failed tests, failed steps, cancelled tests, and uncaught errors emitted from test workers. The specific failure details were already reported per-test through the event stream before this error is returned, so the message itself carries no location information.

Source

Thrown at cli/lsp/testing/execution.rs:509

            test::TestEvent::SnapshotSummary(_) => {}
            test::TestEvent::ForceEndReport => {}
            test::TestEvent::Sigint => {}
            test::TestEvent::Exit(_) => {}
            test::TestEvent::IsolateExit(_, _) => {}
          }
        }

        let elapsed = Instant::now().duration_since(earlier);
        reporter.report_summary(&summary, &elapsed);

        if used_only {
          return Err(anyhow!(
            "Test failed because the \"only\" option was used"
          ));
        }

        if summary.failed > 0 {
          return Err(anyhow!("Test failed"));
        }

        Ok(())
      })
    };

    let (join_results, result) = future::join(join_stream, handler).await;

    // propagate any errors
    for join_result in join_results {
      join_result??;
    }

    result??;

    Ok(())
  }

View on GitHub (pinned to 9ad36f7a2c)

Solutions

1. Read the failure details reported before the summary — Test Explorer failure nodes or the Deno Language Server output panel name the failing tests and their errors.
2. Reproduce outside the LSP with `deno test <file>` (or `deno test --filter <name>`) for full stack traces.
3. Fix the failing tests, or address the uncaught error / cancellation source, then re-run the suite.

// Failures arrive as this terminal error AFTER per-test results streamed in.
try {
  await session.testRun(modules);
} catch (err) {
  if (err?.message === 'Test failed') {
    // details are in the Deno.testEvent notifications already received:
    // surface them (Test Explorer failures / report), never swallow silently
    reportFailuresFromTestEvents();
  } else {
    throw err;
  }
}

When it happens

Trigger: Any LSP-driven test run (VS Code Test Explorer) in which at least one test or step fails, a test is cancelled, or TestEvent::UncaughtError fires from a worker. The handler returns this after reporter.report_summary once summary.failed is non-zero.

Common situations: Red suites run from the IDE; flaky tests cancelled on timeout; uncaught promise rejections inside a test module that fail the run even when all test bodies pass.

Related errors

• Test failed because the "only" option was used
• Snapshot does not match:\n\n ${green("[Diff]")} ${green("
• Expected the second argument to assertSnapshot() to be an op
• Snapshot serializer must return a string
• Missing snapshot file.

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/9732c3c420c9809f. Report an issue: GitHub.