Function withExpectedRejection

packages/db/tests/utils.ts:428–481

(
  expectedMessage: string,
  testFn: () => T | Promise<T>,
)

 * ```
 */
export function withExpectedRejection<T>(
  expectedMessage: string,
  testFn: () => T | Promise<T>,
): Promise<T> {
  return new Promise((resolve, reject) => {
    // Find and temporarily remove the vitest unhandled rejection handler
    const originalUnhandledRejection = process
      .listeners(`unhandledRejection`)
      .find((listener) => listener.name === `vitestUnhandledRejectionHandler`)

    let expectedRejectionCaught = false
    const handleRejection = (reason: any) => {
      if (reason?.message === expectedMessage) {
        expectedRejectionCaught = true
        return // Don't re-throw, this is expected
      }
      // Re-throw other rejections
      reject(reason)
    }

    if (originalUnhandledRejection) {
      process.removeListener(`unhandledRejection`, originalUnhandledRejection)
    }
    process.on(`unhandledRejection`, handleRejection)

    // Execute the test function and handle the result
    Promise.resolve(testFn())
      .then(async (value) => {
        // Wait for microtasks and then check if the rejection was caught
        await flushPromises()

        if (!expectedRejectionCaught) {
          reject(
            new Error(
              `Expected rejection with message "${expectedMessage}" was not caught`,
            ),
          )
          return
        }

        resolve(value)
      })
      .catch((error) => {
        reject(error)
      })
      .finally(() => {
        // Clean up the error handler
        process.removeListener(`unhandledRejection`, handleRejection)
        if (originalUnhandledRejection) {
          process.addListener(`unhandledRejection`, originalUnhandledRejection)
        }
      })
  })
}