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The Cosmos SDK contains different types of tests. These tests have different goals and are used at different stages of the development cycle. We advice, as a general rule, to use tests at all stages of the development cycle. It is adviced, as a chain developer, to test your application and modules in a similar way than the SDK.

The rationale behind testing can be found in ADR-59.

Unit Tests

Unit tests are the lowest test category of the test pyramid. All packages and modules should have unit test coverage. Modules should have their dependencies mocked: this means mocking keepers.

The SDK uses mockgen to generate mocks for keepers:


You can read more about mockgen here.


As an example, we will walkthrough the keeper tests of the x/gov module.

The x/gov module has a Keeper type requires a few external dependencies (ie. imports outside x/gov to work properly).


In order to only test x/gov, we mock the expected keepers and instantiate the Keeper with the mocked dependencies. Note that we may need to configure the mocked dependencies to return the expected values:


This allows us to test the x/gov module without having to import other modules.


We can test then create unit tests using the newly created Keeper instance.


Integration Tests

Integration tests are at the second level of the test pyramid. In the SDK, we locate our integration tests under /tests/integrations.

The goal of these integration tests is to test a component with a minimal application (i.e. not simapp). The minimal application is defined with the help of depinject – the SDK dependency injection framework, and includes all necessary modules to test the component. With the helps of the SDK testing package, we can easily create a minimal application and start the application with a set of genesis transactions:


Here, we will walkthrough the integration tests of the x/distribution module. The x/distribution module has, in addition to keeper unit tests, integration tests that test the x/distribution module with a minimal application. This is expected as you may want to test the x/distribution module with actual application logic, instead of only mocked dependencies.

For creating a minimal application, we use simtestutil.Setup and an AppConfig of the x/distribution minimal dependencies.

For instance, the AppConfig of x/distribution is defined as:

This is a stripped down version of the simapp AppConfig:

Note, you can as well use the AppConfig configurator for creating an AppConfig inline. There no difference between those two ways, use whichever you prefer.


Now the types are injected and we can use them for our tests:


Deterministic and Regression tests

Tests are written for queries in the Cosmos SDK which have module_query_safe Protobuf annotation.

Each query is tested using 2 methods:

  • Use property-based testing with the rapid library. The property that is tested is that the query response and gas consumption are the same upon 1000 query calls.
  • Regression tests are written with hardcoded responses and gas, and verify they don't change upon 1000 calls and between SDK patch versions.

Here's an example of regression tests:



Simulations uses as well a minimal application, built with depinject:

Following is an example for x/gov/ simulations:


End-to-end Tests

End-to-end tests are at the top of the test pyramid. They must test the whole application flow, from the user perspective (for instance, CLI tests). They are located under /tests/e2e.

For that, the SDK is using simapp but you should use your own application (appd). Here are some examples:

Note, the SDK is in the process of creating its E2E tests, as defined in ADR-59. This page will eventually be updated with better examples.


ScopeApp FixtureMocks?