Testing Bindings

Test Containers the way Devflare expects it to run

Containers let a Worker hand requests to stateful code running from a container image.

Test Containers by choosing the local harness that matches the product boundary instead of reaching for Cloudflare by default.

The first test should prove application control flow. Escalate to Wrangler remote binding or deployed tests only when the Cloudflare-hosted behavior is the thing under test.

Best for: routing requests to a stateful container instance that runs code outside the Workers runtime
Default harness: containers helpers guarded by
Escalate when: The assertion depends on Cloudflare-hosted product behavior rather than the app calling the binding correctly

Start with the default test loop

Keep the first test small. Name the binding, call the one method your route uses, and assert the behavior your app owns.

When Cloudflare owns the interesting behavior, mark that as a remote/deployed lane instead of building a local fake that claims too much.

Detect Docker or Podman before running container tests

import { expect, test } from 'bun:test'

import { detectContainerEngine } from 'devflare/test'

test('container engine detection is explicit', async () => {

const status = await detectContainerEngine()

if (!status.available) {

expect(status.reason.length).toBeGreaterThan(0)

return

}

expect(['docker', 'podman']).toContain(status.engine)

})

The helper surface to remember

Use containers helpers guarded by for config-backed local worker tests.
Use / / for pure unit tests.
Use or an explicit integration lane when the test needs Cloudflare credentials or a local Docker/Podman engine.

When to move beyond the default harness

Cloudflare owns deployed container rollout, managed registry availability, SSH, scaling, and hosted platform behavior; Devflare owns the Docker/Podman local loop.
Do not let a low-fidelity mock become product documentation. Keep mocks framed as application-flow tools.
If a test would mutate paid or remote Cloudflare state, gate it separately from ordinary unit tests.

Local tests should be honest

For Containers, passing locally means the Devflare contract and app flow are correct. It does not automatically prove every hosted Cloudflare behavior.

Containers internals

Containers compiles from to Wrangler , with local/test behavior called out explicitly.

Containers example

A compact Containers recipe with config and worker usage in one application path.