Introduce assert_success

bin/git-check-assertions

@@ -32,6 +32,23 @@ assert_fails() {
 }
 export -f assert_fails
 
+# helper functions inspired by bats/bats-assert
+run() {
+  set +e
+  ("$@")
+  status=$?
+  set -e
+  return 0
+}
+assert_success() {
+  if [ "$status" -ne 0 ]; then
+    echo "Expected command to succeed, but it failed."
+    exit 1
+  fi
+}
+export -f run assert_success
+
+# main flow
 orig_ref="$(git symbolic-ref --quiet --short HEAD || git rev-parse HEAD)"
 base="$(git merge-base main HEAD)"
 mapfile -t commits < <(git rev-list --reverse "${base}..HEAD")