# Test design
The `warp-sync` test works on predefined database which is stored in the cloud and
fetched by the test. `alice` and `bob` nodes are spun up using this database snapshot in full node mode.

As `warp-sync` requires at least 3 peers, the test spawns the `charlie` full node which uses the same database snapshot.

The `dave` node executed with `--sync warp` syncs database with the rest of the network.

# How to prepare database
Database was prepared using the following zombienet file (`generate-warp-sync-database.toml`):
```
[relaychain]
default_image = "docker.io/paritypr/substrate:master"
default_command = "substrate"

chain = "local"

chain_spec_path = "chain-spec.json"

  [[relaychain.nodes]]
  name = "alice"
  validator = true

  [[relaychain.nodes]]
  name = "bob"
  validator = true
```

The zombienet shall be executed with the following command, and run for some period of time to allow for few grandpa eras.
```
./zombienet-linux spawn --dir ./db-test-gen --provider native generate-warp-sync-database.toml
```

Once the zombienet is stopped, the database snapshot
(`alice/data/chains/local_testnet/db/` dir) was created using the following
commands:
```bash
mkdir -p db-snapshot/alice/data/chains/local_testnet/db/
cp -r db-test-gen/alice/data/chains/local_testnet/db/full db-snapshot/alice/data/chains/local_testnet/db/
```

Sample command to prepare archive:
```
tar -C db-snapshot/alice/ -czf chains.tgz ./
```

The file format should be `tar.gz`. File shall contain `local_testnet` folder and its subfolders, e.g.:
```
$ tar tzf chains.tgz | head
data/chains/local_testnet/
data/chains/local_testnet/db/
data/chains/local_testnet/db/full/
...
data/chains/local_testnet/db/full/000469.log
```

Also refer to: [zombienet#578](https://github.com/paritytech/zombienet/issues/578)

The `raw` chain-spec shall also be saved: `db-test-gen/local.json`.

# Where to upload database
The access to this [bucket](https://console.cloud.google.com/storage/browser/zombienet-db-snaps/) is required.

Sample public path is: `https://storage.googleapis.com/zombienet-db-snaps/substrate/0001-basic-warp-sync/chains-0bb3f0be2ce41b5615b224215bcc8363aa0416a6.tgz`.

The database file path should be `substrate/XXXX-test-name/file-SHA1SUM.tgz`, where `SHA1SUM` is a `sha1sum` of the file.

# Chain spec
Chain spec was simply built with:
```
substrate build-spec --chain=local > chain-spec.json
```

Please note that `chain-spec.json` committed into repository is `raw` version produced by `zombienet` during database
snapshot generation. Zombienet applies some modifications to plain versions of chain-spec.

# Run the test
Test can be run with the following command:
```
zombienet-linux test --dir db-snapshot --provider native test-warp-sync.zndsl
```


# Save some time hack
Substrate can be patched to reduce the grandpa session period.
```
diff --git a/bin/node/runtime/src/constants.rs b/bin/node/runtime/src/constants.rs
index 23fb13cfb0..89f8646291 100644
--- a/bin/node/runtime/src/constants.rs
+++ b/bin/node/runtime/src/constants.rs
@@ -63,7 +63,7 @@ pub mod time {

    // NOTE: Currently it is not possible to change the epoch duration after the chain has started.
    //       Attempting to do so will brick block production.
-   pub const EPOCH_DURATION_IN_BLOCKS: BlockNumber = 10 * MINUTES;
+   pub const EPOCH_DURATION_IN_BLOCKS: BlockNumber = 1 * MINUTES / 2;
    pub const EPOCH_DURATION_IN_SLOTS: u64 = {
        const SLOT_FILL_RATE: f64 = MILLISECS_PER_BLOCK as f64 / SLOT_DURATION as f64
```