test-runtime

The logic for this crate exists mainly in the build.rs file.

At compile time, this crate will:

• Spin up a local substrate binary (set the SUBSTRATE_NODE_PATH env var to point to a custom binary, otherwise it'll look for substrate on your PATH).
• Obtain metadata from this node.
• Export the metadata and a node_runtime module which has been annotated using the subxt proc macro and is based off the above metadata.

The reason for doing this is that our integration tests (which also spin up a Substrate node) can then use the generated subxt types from the exact node being tested against, so that we don't have to worry about metadata getting out of sync with the binary under test.