Fix Java tests in preparation for --incompatible_load_proto_rules_from_bzl

Closes #9140.

PiperOrigin-RevId: 264170421
diff --git a/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java b/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java
index 41358c6..38f9d36 100644
--- a/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java
+++ b/src/test/java/com/google/devtools/build/lib/testutil/TestConstants.java
@@ -25,6 +25,11 @@
  */
 public class TestConstants {
 
+  public static final String LOAD_PROTO_LIBRARY =
+      "load('@rules_proto//proto:defs.bzl', 'proto_library')";
+  public static final String LOAD_PROTO_LANG_TOOLCHAIN =
+      "load('@rules_proto//proto:defs.bzl', 'proto_lang_toolchain')";
+
   private TestConstants() {
   }