Prevent dynamic boundaries on multipart/form-data pacts

[marcozet]

We have a scenario where we need to upload a bunch of files using post with Content-Type multipart/form-data.

So the request body looks like...

--m5owueqDDBp_nPEBOX-JvuMixxacXChqVMnc6
Content-Disposition: form-data; name="files"; filename="foo.txt"
Content-Type: text/plain

foo
--m5owueqDDBp_nPEBOX-JvuMixxacXChqVMnc6
Content-Disposition: form-data; name="files"; filename="bar.txt"
Content-Type: text/plain

bar
--m5owueqDDBp_nPEBOX-JvuMixxacXChqVMnc6--

and the Pact is generated as...

@Pact(consumer = "consumer-service", provider = "file-upload-service")
public RequestResponsePact upload(PactDslWithProvider builder) throws IOException {
    DslPart responseBody = newJsonBody((body) -> {
                body.uuid("uploadId")
    })
    .build();

    return builder.given("001: no data available")
            .uponReceiving("request to upload a file")
            .path(BASE_URI + "/uploads")
            .method("POST")
            .headers(Map.of("Content-Type", MediaType.MULTIPART_FORM_DATA_VALUE))
            .withFileUpload(
                    "files",
                    "bar.txt",
                    "application/octet-stream",
                    new ClassPathResource("foo.txt").getContentAsByteArray())
            .withFileUpload(
                    "file",
                    "foo.txt",
                    "application/octet-stream",
                    new ClassPathResource("bar.txt").getContentAsByteArray())
            .willRespondWith()
            .status(HttpStatus.OK.value())
            .body(responseBody)
            .toPact();
}

No issues so far.

We use the Pact Broker / Pact webhook workflow, so we publish the Pact file to the broker and the provider verification is triggered via the webhook when the content of the Pact file has changed (on contract_content_changed event).

But unfortunately, the generated and published Pact file differs from test run to test run, as the boundary in the request body that marks the various parts is generated dynamically.

As a result, the Pact broker triggers the provider verification for each consumer build, even though the Pact itself has not been changed (except for the boundary attribute).

Can I set the boundary attribute statically so that the Pact doesn't change?

I found a similar problem here: pact-foundation/pact-net#410 (comment)

[rholshausen]

If you use the MultipartEntityBuilder from the Apache HTTP client, you can set the boundary to a fixed value (using setBoundary).

Example test using MultipartEntityBuilder

pact-jvm/consumer/junit/src/test/groovy/au/com/dius/pact/consumer/junit/ExampleMultipartSpec.groovy

Line 18 in 4752365

class ExampleMultipartSpec {

[marcozet]

OK, got it! Now it works... Thanks.