tools: add script to make reviewing backport PRs easier

PR-URL: #59161
Reviewed-By: Moshe Atlow <[email protected]>

Author: aduh95

tools/actions/review_backport.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+BACKPORT_PR=$1
+
+[ -n "$BACKPORT_PR" ] || {
+    echo "Usage:"
+    echo 'tools/actions/review_backport.sh https://github.com/nodejs/node/pull/<backport-PR-number> | less'
+    echo 'DIFF_CMD="codium --wait --diff" tools/actions/review_backport.sh https://github.com/nodejs/node/pull/<backport-PR-number>'
+    echo "Limitations: This tools only supports PRs that landed as single commit, e.g. with 'commit-queue-squash' label."
+
+    exit 1
+}
+
+SED_CMD='s/^index [a-f0-9]\+..[a-f0-9]\+ \([0-7]\{6\}\)$/index eeeeeeeeee..eeeeeeeeee \1/g;s/^@@ -[0-9]\+,[0-9]\+ +[0-9]\+,[0-9]\+ @@/@@ -111,1 +111,1 @@/'
+
+set -ex
+
+ORIGINAL=$(mktemp)
+BACKPORT=$(mktemp)
+gh pr view "$BACKPORT_PR" --json commits --jq '.[] | map([ .oid, (.messageBody | match("(?:^|\\n)PR-URL: (https?://.+/pull/\\d+)(?:\\n|$)", "g") | .captures | last | .string)] | @tsv) | .[]' \
+| while read -r LINE; do
+  COMMIT_SHA=$(echo "$LINE" | cut -f1)
+  PR_URL=$(echo "$LINE" | cut -f2)
+
+  curl -fsL "$PR_URL.diff" | sed "$SED_CMD" >> "$ORIGINAL"
+  curl -fsL "$BACKPORT_PR/commits/$COMMIT_SHA.diff" | sed "$SED_CMD" >> "$BACKPORT"
+done
+
+${DIFF_CMD:-diff} "$ORIGINAL" "$BACKPORT"
+rm "$ORIGINAL" "$BACKPORT"