dapp: Gas snapshotting

src/dapp-tests/integration/tests.sh

@@ -225,6 +225,34 @@ test_custom_solc_json() {
     assert "[[ -f out/dapp.sol.json ]]"
 }
 
+test_gas_snapshots() {
+    tmp=$(mktemp -d)
+
+    # copy source file
+    mkdir -p "$tmp/src"
+    cp "$CONTRACTS/factor.sol" "$tmp/src"
+
+    # init dapp project
+    cd "$tmp" || exit
+    export GIT_CONFIG_NOSYSTEM=1
+    export GIT_AUTHOR_NAME=dapp
+    export GIT_AUTHOR_EMAIL=dapp@hub.lol
+    export GIT_COMMITTER_NAME=$GIT_AUTHOR_NAME
+    export GIT_COMMITTER_EMAIL=$GIT_AUTHOR_EMAIL
+    dapp init
+
+    # test with snapshots
+    dapp snapshot
+    assert "[[ -f .gas-snapshot ]]"
+
+    # test check snapshots
+    dapp check-snapshot || fail
+
+    # check that check snapshots fails if we change the snapshot
+    echo this_will_change_the_snapshot > .gas-snapshot
+    dapp check-snapshot && fail || echo "dapp success: snapshot diff detected"
+}
+
 test_nonce_1() {
     local account
     account=$(fresh_account)

src/dapp/CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - The output from `dapp build` now uses color to differentiate warnings and errors
 - Support for solc 0.8.9/0.8.8
 
+- `dapp snapshot` and `dapp check-snapshot` commands to snapshot test gas usage.
+
 ### Changed
 
 - Dapp remappings ignores non-directories in `DAPP_LIB`

src/dapp/README.md

@@ -545,6 +545,20 @@ it. For an example, see [this repo](https://github.com/dapp-org/radicle-contract
 
 Updates a project submodule in the `lib` subdirectory.
 
+### `dapp snapshot`
+
+    dapp-snapshot -- creates a snapshot of each test's gas usage
+    Usage: dapp snapshot
+
+Saves a snapshot of each concrete test's gas usage in a `.gas-snapshot` file.
+
+### `dapp check-snapshot`
+
+    dapp-check-snapshot -- check snapshot is up to date
+    Usage: dapp check-snapshot
+
+Runs `dapp snapshot` and exits with an error code if its output does not match the current `.gas-snapshot` file.
+
 ### `dapp upgrade`
 
     dapp-upgrade -- pull & commit all upstream lib changes
@@ -558,7 +572,7 @@ Spins up a geth testnet.
 
     dapp-verify-contract -- verify contract source on etherscan
     Usage: dapp verify-contract <path>:<contractname> <address> [constructorArgs]
-    
+
 Example: `dapp verify-contract src/auth/authorities/RolesAuthority.sol:RolesAuthority 0x9ed0e..`
 
 Requires `ETHERSCAN_API_KEY` to be set.

src/dapp/libexec/dapp/dapp-check-snapshot

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+### dapp-check-snapshot -- check snapshot is up to date
+### Usage: dapp check-snapshot
+set -e
+
+# Uses the output of dapp test to compare with dapp snapshot
+DIFF="$(diff .gas-snapshot <(dapp test --fuzz-runs 0 | grep 'gas:' | cut -d " " -f 2-4))"
+
+if [ -n "$DIFF" ]
+then
+   echo "$DIFF"
+   exit 1
+fi

src/dapp/libexec/dapp/dapp-snapshot

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+### dapp-snapshot -- creates a snapshot of each test's gas usage
+### Usage: dapp snapshot
+set -e
+
+# Saves the output of dapp test to .gas-snapshot
+dapp test --fuzz-runs 0 | grep 'gas:' | cut -d " " -f 2-4 > .gas-snapshot