Merge pull request #39344 from spxtr/boilerplate_test

Automatic merge from submit-queue (batch tested with PRs 39022, 39331, 39070, 39344)

Add a build rule for the boilerplate unit test.

We recently added unit tests that just run whenever you run `hack/verify_boilerplate.sh`, which really isn't the right time to do that. This adds a build rule instead.

hack/boilerplate/BUILD

@@ -1,3 +1,12 @@
 package(default_visibility = ["//visibility:public"])
 
 exports_files(glob(["*.txt"]))
+
+py_test(
+    name = "boilerplate_test",
+    srcs = [
+        "boilerplate_test.py",
+        "boilerplate.py",
+    ],
+    data = glob(["*.txt", "test/*"]),
+)