diff --git a/library.sh b/library.sh
index 798abc27..9cd2adc7 100755
--- a/library.sh
+++ b/library.sh
@@ -138,16 +138,22 @@ function calcRetcode() {
   echo "$rc"
 }
 
+# Print error message.
+# Parameters: $* - error message to be displayed
+function error() {
+  gum_style \
+      --foreground '#D00' \
+      --padding '1 3' \
+      --border double \
+      --border-foreground '#D00' \
+      "ERROR: $*"
+}
+
 # Print error message and call exit(n) where n calculated from the error message.
 # Parameters: $1..$n - error message to be displayed
 # Globals: abort_retcode will change the default retcode to be returned
 function abort() {
-  gum_style \
-    --foreground '#D00' \
-    --padding '1 3' \
-    --border double \
-    --border-foreground '#D00' \
-    "ERROR: $*"
+  error "$*"
   readonly abort_retcode="${abort_retcode:-$(calcRetcode "$*")}"
   exit "$abort_retcode"
 }
@@ -169,7 +175,8 @@ function make_banner() {
 
 # Simple header for logging purposes.
 function header() {
-  local upper="$(echo "$*" | tr a-z A-Z)"
+  local upper
+  upper="$(echo "$*" | tr '[:lower:]' '[:upper:]')"
   gum_style \
     --padding '1 3' \
     --border double \
diff --git a/test/e2e/apis/hack/register.go b/test/codegen/testdata/apis/hack/register.go
similarity index 100%
rename from test/e2e/apis/hack/register.go
rename to test/codegen/testdata/apis/hack/register.go
diff --git a/test/e2e/apis/hack/v1alpha1/doc.go b/test/codegen/testdata/apis/hack/v1alpha1/doc.go
similarity index 100%
rename from test/e2e/apis/hack/v1alpha1/doc.go
rename to test/codegen/testdata/apis/hack/v1alpha1/doc.go
diff --git a/test/e2e/apis/hack/v1alpha1/example_types.go b/test/codegen/testdata/apis/hack/v1alpha1/example_types.go
similarity index 100%
rename from test/e2e/apis/hack/v1alpha1/example_types.go
rename to test/codegen/testdata/apis/hack/v1alpha1/example_types.go
diff --git a/test/e2e/apis/hack/v1alpha1/register.go b/test/codegen/testdata/apis/hack/v1alpha1/register.go
similarity index 97%
rename from test/e2e/apis/hack/v1alpha1/register.go
rename to test/codegen/testdata/apis/hack/v1alpha1/register.go
index c66a84cd..04ec86a7 100644
--- a/test/e2e/apis/hack/v1alpha1/register.go
+++ b/test/codegen/testdata/apis/hack/v1alpha1/register.go
@@ -20,8 +20,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
-
-	"knative.dev/hack/test/e2e/apis/hack"
+	"knative.dev/hack/test/codegen/testdata/apis/hack"
 )
 
 // SchemeGroupVersion is group version used to register these objects
diff --git a/test/e2e/apis/hack/v1alpha1/zz_generated.deepcopy.go b/test/codegen/testdata/apis/hack/v1alpha1/zz_generated.deepcopy.go
similarity index 100%
rename from test/e2e/apis/hack/v1alpha1/zz_generated.deepcopy.go
rename to test/codegen/testdata/apis/hack/v1alpha1/zz_generated.deepcopy.go
diff --git a/test/hack/update-codegen.sh b/test/hack/update-codegen.sh
index ffe61cf2..b25c7365 100755
--- a/test/hack/update-codegen.sh
+++ b/test/hack/update-codegen.sh
@@ -22,7 +22,7 @@ relative_rootdir="$(realpath -s --relative-to="$PWD" "$rootdir")"
 source "$(go run "${relative_rootdir}/cmd/script" codegen-library.sh)"
 
 generate-groups deepcopy \
-  knative.dev/hack/test/e2e/apis/hack/v1alpha1/generated \
-  knative.dev/hack/test/e2e/apis \
+  knative.dev/hack/test/codegen/testdata/apis/hack/v1alpha1 \
+  knative.dev/hack/test/codegen/testdata/apis \
   hack:v1alpha1 \
   "$@"
diff --git a/test/hack/verify-codegen.sh b/test/hack/verify-codegen.sh
new file mode 100755
index 00000000..72b6ee76
--- /dev/null
+++ b/test/hack/verify-codegen.sh
@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+
+# Copyright 2024 The Knative Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -Eeuo pipefail
+
+rootdir="$(realpath "$(dirname "${BASH_SOURCE[0]:-$0}")/../..")"
+cd "${rootdir}"
+
+# shellcheck disable=SC1090
+source "$(go run ./cmd/script library.sh)"
+
+./test/hack/update-codegen.sh
+
+if ! git diff --exit-code; then
+  abort "codegen is out of date, please run test/hack/update-codegen.sh, and commit the changes."
+fi
+
+header "Codegen is up to date"
diff --git a/test/presubmit-tests.sh b/test/presubmit-tests.sh
index cf0b34a3..e539a148 100755
--- a/test/presubmit-tests.sh
+++ b/test/presubmit-tests.sh
@@ -34,7 +34,7 @@ function post_build_tests() {
   local failed=0
   for script in *.sh; do
     subheader "Checking integrity of ${script}"
-    bash -c "source ${script}" || { failed=1; echo "--- FAIL: ${script}"; }
+    bash -c "source ${script}" || { failed=1; error "${script}"; }
   done
   return ${failed}
 }