PACT is a tool introduced to enable to testing of API contract between the consumer (the system that uses the API) and the provider (the system that produces the API). It is available in a couple of different languages. The version that I have been using is the JVM version in Groovy. This tool is very useful to detect API structure changes. It is good in the sense that we can test the structure of the API irrespective of the data (we can just test the data type). It could be easily integrated into CI box as well.
Consumer test defines the contract or structure of the API that the system uses. It can be used to enable TDD and in a situation when the system that consumes the API is built before the API exist. Upon successful consumer test run, a JSON file that mimic the actual API output will be generated under the “target” folder.
Provider test basically is a call to the actual API which then compares the actual API result with the structure which we expect (as defined in the Consumer test). It is built in the build script depending on which framework that we use, in my case it is called in the build.grade file.
I will include more specific examples with descriptions on the Consumer and Provider tests in my upcoming posts.