CI Regression Test for determinism of our wasm runtimes (#1372)

* deterministic build check runtime

* fix yaml

* Apply suggestions from code review

Co-authored-by: s3krit <pugh@s3kr.it>

* Update cargo.lock

Co-authored-by: s3krit <pugh@s3kr.it>

polkadot/.gitlab-ci.yml

@@ -105,6 +105,23 @@ publish-draft-release:
   interruptible:                   true
   allow_failure:                   true
 
+test-deterministic-wasm:
+  stage:                           test
+  <<:                              *docker-env
+  except:
+  script:
+    # build runtime
+    - WASM_BUILD_NO_COLOR=1 cargo build --verbose --release -p kusama-runtime -p polkadot-runtime -p westend-runtime
+    # make checksum
+    - sha256sum target/release/wbuild/target/wasm32-unknown-unknown/release/*.wasm > checksum.sha256
+    # clean up – FIXME: can we reuse some of the artifacts?
+    - cargo clean
+    # build again
+    - WASM_BUILD_NO_COLOR=1 cargo build --verbose --release -p kusama-runtime -p polkadot-runtime -p westend-runtime
+    # confirm checksum
+    - sha256sum -c checksum.sha256
+
+
 test-linux-stable:                 &test
   stage:                           test
   <<:                              *test-refs