Split crates.io fetch logic from SemVer action

Author: spinda

.github/scripts/check-out-base-from-crates-io.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+set -euo pipefail
+
+cedar_policy_version="$(
+  cd head &&
+  cargo metadata --format-version 1 |
+    jq --raw-output '.packages[] | select(.name == "cedar-policy") | .version'
+)"
+echo "HEAD has cedar-policy at ${cedar_policy_version}"
+
+tmp_dir="$(mktemp -d)"
+function cleanup {
+  rm -rf "${tmp_dir}"
+}
+trap cleanup EXIT
+
+(
+  cd "${tmp_dir}"
+
+  cat <<EOF >Cargo.toml
+[package]
+name = "cedar-semver-checks"
+version = "0.0.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+cedar-policy = "<=${cedar_policy_version}"
+EOF
+
+  mkdir src
+  touch src/lib.rs
+
+  cargo vendor
+)
+
+mkdir base
+mv "${tmp_dir}/vendor/cedar-policy" base/
+cat <<EOF >base/Cargo.toml
+[workspace]
+members = ["cedar-policy"]
+EOF

.github/workflows/ci.yml

@@ -64,43 +64,8 @@ jobs:
       # published to crates.io <= the version from head.
       - if: ${{ startsWith(github.base_ref, 'release/') }}
         name: Check out base (from crates.io)
+        run: head/.github/scripts/check-out-base-from-crates-io.sh
         shell: bash
-        run: |-
-          cedar_policy_version="$(
-            cd head &&
-            cargo metadata --format-version 1 |
-              jq --raw-output '.packages[] | select(.name == "cedar-policy") | .version'
-          )"
-          echo "HEAD has cedar-policy at ${cedar_policy_version}"
-
-          tmp_dir="$(mktemp -d)"
-          function cleanup {
-            rm -rf "${tmp_dir}"
-          }
-          trap cleanup EXIT
-
-          (
-            cd "${tmp_dir}"
-
-            echo "[package]
-            name = \"cedar-semver-checks\"
-            version = \"0.0.0\"
-            edition = \"2021\"
-            publish = false
-
-            [dependencies]
-            cedar-policy = \"<=${cedar_policy_version}\"" > Cargo.toml
-
-            mkdir src
-            touch src/lib.rs
-
-            cargo vendor
-          )
-
-          mkdir base
-          mv "${tmp_dir}/vendor/cedar-policy" base/
-          echo '[workspace]
-          members = ["cedar-policy"]' > base/Cargo.toml
       # `cargo semver-checks` doesn't understand `rlib` crates.
       - run: >-
           sed -i 's/^crate_type = \["rlib"\]$/crate_type = ["lib"]/' {head,base}/cedar-policy/Cargo.toml