ProviderStateGenerator only supports path matching via IntegrationJson (FFI)

[mefellows]

Via: pact-foundation/pact-js#1223

Relates to : #447

Upon investigating pact-foundation/pact-js#1223, the following use cases stopped working - possibly they were only working because of the presence of the type matcher which masked the problem:

query strings:

2024-06-21T03:55:39.588275Z DEBUG tokio-runtime-worker pact_matching: --> Mismatches: [QueryMismatch { parameter: "accountNumber", expected: "{\"expression\":\"${accountNumber}\",\"value\":\"100\"}", actual: "100", mismatch: "Expected query parameter 'accountNumber' with value '{\"expression\":\"${accountNumber}\",\"value\":\"100\"}' but was '100'" }]
2024-06-21T03:55:39.588472Z DEBUG tokio-runtime-worker pact_mock_server::hyper_server: Request did not match: Request did not match - HTTP Request ( method: GET, path: /accounts/search/findOneByAccountNumberId, query: Some({"accountNumber": ["{\"expression\":\"${accountNumber}\",\"value\":\"100\"}"]}), headers: Some({"Accept": ["application/hal+json"]}), body: Missing )    0) Expected query parameter 'accountNumber' with value '{"expression":"${accountNumber}","value":"100"}' but was '100'

Bodies:

2024-06-21T03:57:04.428658Z DEBUG tokio-runtime-worker pact_matching: --> Mismatches: [BodyMismatch { path: "$.accountNumber", expected: Some(b"{\"expression\":\"${accountNumber}\",\"value\":100}"), actual: Some(b"100"), mismatch: "Type mismatch: Expected 100 (Integer) to be the same type as {\"expression\":\"${accountNumber}\",\"value\":100} (Object)" }]
2024-06-21T03:57:04.428951Z DEBUG tokio-runtime-worker pact_mock_server::hyper_server: Request did not match: Request did not match - HTTP Request ( method: POST, path: /accounts/search/findOneByAccountNumberIdInBody, query: None, headers: Some({"Content-Type": ["application/json"], "Accept": ["application/hal+json"]}), body: Present(63 bytes, application/json) )    0) $.accountNumber -> Type mismatch: Expected 100 (Integer) to be the same type as {"expression":"${accountNumber}","value":100} (Object)

And presumably headers (I don’t have a test for this).

The only one that works is when it's used in a path expression.

It looks like the expression is not being set properly, as you can see the JSON format instead of the expected value.

[mefellows]

Further investigation needed to identify the source of the problem, we may also need to update https://github.com/pact-foundation/pact-reference/blob/master/rust/pact_ffi/IntegrationJson.md to clarify the use of the FFI interop format.