The ibc-test-framework crate provides the infrastructure and framework for writing end-to-end (E2E) tests that include the spawning of the relayer together with Cosmos full nodes running as child processes inside the tests.
Other than Rust, the test suite assumes the gaiad binary is present in $PATH. You can install Gaia by either building from source, or load it using Cosmos.nix:
nix shell github:informalsystems/cosmos.nix#gaia11
Alternatively, you can use $CHAIN_COMMAND_PATH to override with a different executable that is compatible with gaiad.
Example tests written using ibc-test-framework can be found in the ibc-rs project repository
Some diagrams have been prepared to ease the understanding of the test framework: