verification of single-value header fails due to splitting at commas

[torbendorc]

Hi there!

I tried to update to version 4.1.14 of au.com.dius.pact.provider:junit5spring and came over an issue that might be a regression on #1159.

We have a pact contract with an interaction that has an "Expires" header in it's response.

...
  "response": {
    "status": 200,
    "headers": {
      "Expires": "Sat, 27 Nov 1999 12:00:00 GMT",
      "Content-Type": "application/json"
    },
...

Till au.com.dius.pact.provider:junit5spring:4.1.6 the header was compared like this:

Comparing header 'Expires': 'Sat' to 'Sat'
Comparing header 'Expires': '27 Nov 1999 12:00:00 GMT' to '27 Nov 1999 12:00:00 GMT'

Since au.com.dius.pact.provider:junit5spring:4.1.7 the header is compared like this:

Comparing header 'Expires': 'Sat, 27 Nov 1999 12:00:00 GMT' to 'Sat'
Comparing header 'Expires': '' to '27 Nov 1999 12:00:00 GMT'

The latter fails verification.

Might be that this came along with fix fa0f3f9 that introduced a fixed list of SINGLE_VALUE_HEADERS, if I understood it corretly. So in the pact response model that is parsed from the http response there is just one key-value pair for single-value headers.
But in contrast to this the other side that parses the pact contract, that comes from the broker, doesn't know single-value headers and still splits the value at commas (see the model).

One might issue that the contract should have the single value in an array like this:

...
  "response": {
    "status": 200,
    "headers": {
      "Expires": ["Sat, 27 Nov 1999 12:00:00 GMT"],
      "Content-Type": "application/json"
    },
...

But this is no option when generating the contract with pact-js (web), i think.

I'm not sure whether I got the process right or not, but I hope my pre-analysis helps analysing this issue.

THX in advance for paying attention to this issue! 😉