Comparison: Specmatic vs Spring Cloud Contract

This is the third post in our series where we compare Specmatic with tools that have some overlap in terms of capabilities. In our previous posts we compared Specmatic with Pact and WireMock. In this post we will be looking at Spring Cloud Contract.

With Spring Cloud Contract we can start by authoring the API contract in one of the supported DSLs, based on which the provider / producer is verified and in the process stubs are generated for consumers. This makes it possible to leverage it as both a “consumer driven” or “provider driven” contract testing tool. There are also some interesting points about how we share contracts and stubs (through artifact managers, source control, etc.) with Spring Cloud Contract. Let us look at the detailed comparison between Specmatic and Spring Cloud Contract. Please do leave a comment if there are other areas of comparison on which you would like to see additional details.

Platform	Specmatic.in	Spring Cloud Contract
Approach	Contract Driven Development (CDD)	Consumer Driven Contract (CDC), Provider Driven Contract
OpenAPI Support	YES Specmatic leverages OpenAPI Specifications as Executable Contracts	NO API Contracts are defined with Groovy DSL, YAML, Pact JSON and Spring Rest Docs (There are external tools / libraries which may help with leveraging OpenAPI Specifications)
Suitable for Consumer First Development Style (Frontend Before Backend)	YES Consumer Team can author the API Specification, leverage it as mock / stub and then share it with Provider team as a guideline	YES CAVEAT – However you have to wait for the contract to be translated into stub on the Provider Side
Suitable for Provider First Development Style (Backend Before Frontend, public facing APIs, ec.)	YES Provider Team can author the API Specification, leverage as tests and then share it with Consumer team to stub the Provider	YES Provider can author the contract, run it as test, generated stubs and publish it for Consumers
Suitable for API First Development Style	YES Consumer and Provider Teams collaboratively author API Specification and only then being development	YES CAVEAT – In Spring Cloud Contract, we begin by authoring the API Contract in Contract DSL. However this is not the API Specification which you have to additionally maintain.
Parallel Development of Consumer and Provider	YES This is one of the primary capabilities of Specmatic, to allow teams to independently develop and confidently deploy microservices	PARTIAL Consumer has to wait for Provider to run the Contract Verification and publish the stubs be it in Consumer Driven Contract or Provider Driven Contract approach
Backward Compatibility Verification #NOCODE	YES This is one of the flagship capabilities in Specmatic. Contract vs Contract comparison, no need to implement the changes in Provider or Consumer Code	NO It is not possible to identify backward compatiliblity issues withouth implementing / writing code for Provider and Consumer. Backward breaking changes can be identified only by running verifier on provider and stub runner for consumers.
API Specifications as Test #NOCODE	YES Specmatic can generate and run tests all with just your OpenAPI specifications	NO Spring Cloud Contract runs its Contract DSL as Test with verifier, OpenAPI cannot be run as tests
Negative / Boundary Testing	YES Specmatic not only runs your API Spec as a Contract Tests for happy path scenarios, it can also verify your application’s behaviour for negative inputs	NO
API Specifications as Stub #NOCODE	YES OpenAPI is all you need to run a stub server, no need to define a stub, just the expectation data	NO Spring Cloud Contract DSL necessary to define the Contract which are then leveraged during verification to generate Stubs
Smart Mocks (Stale Stub Detection / Expectation Validation against API Specification)	YES Immediate Feedback, expectations that are not as per API Spec are immediately rejected with proper error message	NO / Not Applicable. Expectations / response mappings are defined as part of contract itself based on which the stub jars are generated with wiremock mappings jsons.
Unfragmented Devex / Minimal learning curve	YES You just need API Specification of your choice such as OpenAPI and Specmatic – no additional DSLs	NO In Java and Spring Ecosystem, we only need to know the Contract DSL, verifier and stub runner dependencies, build tools like mvn or gradle and an artifact manager. In polyglot mode the verifier and stub runner are dockerised and contracts / stubs can be stored in source control such as git. Spring Cloud Contract also has Pact integration to extend some of its functionality, however too many tools can add to the complexity. If you are also adopting OpenAPI then that will be completely additional.
Can all stakeholders participate / author Contracts / API Specifications	YES Devs, architects, test engineers, practically anyone who can author an OpenAPI Spec.	NO Contracts can only be authored by someone who understands one of the supported DSLs
Suitable for adoption in Greenfield Projects	YES Specmatic helps team become productive quickly with Contract Driven Development	YES
Suitable for adoption in Brownfield Projects	YES Specmatic can immediately provide value on existing projects and helps the team slowly adopt Contract Driven Development	YES
Minimal / No Leakage for Compatibility Issues	YES Specmatic keeps a tight check on both the Consumer and Provider and immediately provides feedback where they deviate from API Specification thereby preventing compatibility Issues	YES The feedback cycle can be slower since consumers have to wait for stubs to be generated and shared by producer
Low Cost of Maintenance	YES Since Specmatic is leveraging your API Specifications there is no maintenance overhead. You just need to maintain your Stub / Expectation data.	NO In comparison to Specmatic which only needs API Specifications, you need to maintain the Contracts which are written in one of the supported DSLs
Open Source	YES License – MIT	YES
Language and Platform Agnostic	YES Is able to work completely as a standalone executable	YES Spring Cloud Contract supports YAML DSL and also has Dockerised verifier and stub runner
Unlimited Team Size	YES	YES
Broker Less	YES Requires no server setup	YES CAVEAT – Spring Cloud Contract itself is brokerless, however when integrated with Pact, it can work with Pact Broker

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