tools: add automation for updating postject dependency

.github/workflows/tools.yml

@@ -77,6 +77,16 @@ jobs:
                 echo "NEW_VERSION=$NEW_VERSION" >> $GITHUB_ENV
                 ./tools/update-undici.sh
               fi
+          - id: postject
+            subsystem: deps
+            label: dependencies
+            run: |
+              NEW_VERSION=$(npm view postject dist-tags.latest)
+              CURRENT_VERSION=$(node -p "require('./test/fixtures/postject-copy/node_modules/postject/package.json').version")
+              if [ "$NEW_VERSION" != "$CURRENT_VERSION" ]; then
+                echo "NEW_VERSION=$NEW_VERSION" >> $GITHUB_ENV
+                ./tools/update-postject.sh
+              fi
           - id: base64
             subsystem: deps
             label: dependencies

doc/contributing/maintaining-postject.md

@@ -0,0 +1,23 @@
+# Maintaining postject
+
+The [postject](https://github.com/nodejs/postject) dependency is used for the
+[Single Executable strategic initiative](https://github.com/nodejs/single-executable).
+
+## Updating postject
+
+The `tools/update-postject.sh` script automates the update of the postject
+source files.
+
+Check that Node.js still builds and tests.
+
+## Committing postject
+
+Add postject: `git add --all test/fixtures/postject-copy`
+
+Commit the changes with a message like
+
+```text
+deps: update postject to 1.0.0-alpha.4
+
+Updated as described in doc/contributing/maintaining-postject.md.
+```

tools/update-postject.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+# Shell script to update postject in the source tree to the latest release.
+
+# This script must be in the tools directory when it runs because it uses the
+# script source file path to determine directories to work in.
+
+set -ex
+
+cd "$( dirname "$0" )/.." || exit
+rm -rf test/fixtures/postject-copy
+
+mkdir test/fixtures/postject-copy
+cd test/fixtures/postject-copy || exit
+
+ROOT="$PWD/../../.."
+[ -z "$NODE" ] && NODE="$ROOT/out/Release/node"
+[ -x "$NODE" ] || NODE=$(command -v node)
+NPM="$ROOT/deps/npm/bin/npm-cli.js"
+
+"$NODE" "$NPM" init --yes
+
+"$NODE" "$NPM" install --no-bin-links --ignore-scripts postject