[Thinkit] Adding p4info_helper_test.cc to test/lib.

tests/lib/BUILD.bazel

@@ -35,6 +35,16 @@ cc_library(
     ],
 )
 
+cc_test(
+    name = "p4info_helper_test",
+    srcs = ["p4info_helper_test.cc"],
+    deps = [
+        ":p4info_helper",
+        "//p4_pdpi:ir_cc_proto",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
 cc_library(
     name = "p4rt_fixed_table_programming_helper",
     testonly = True,

tests/lib/p4info_helper_test.cc

@@ -0,0 +1,39 @@
+// Copyright 2024 Google LLC
+//
+// 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
+//
+//     https://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.
+#include "tests/lib/p4info_helper.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "p4_pdpi/ir.pb.h"
+
+namespace gpins {
+namespace {
+
+TEST(P4InfoHelperTest, TableHasMatchField) {
+  // Add a 'good' match field to a table definition.
+  pdpi::IrTableDefinition table_def;
+  table_def.mutable_match_fields_by_name()->insert(
+      {"good_match", pdpi::IrMatchFieldDefinition{}});
+
+  // Then add that table definition to an IrP4Info.
+  pdpi::IrP4Info ir_p4info;
+  ir_p4info.mutable_tables_by_name()->insert({"good_table", table_def});
+
+  EXPECT_TRUE(pins::TableHasMatchField(ir_p4info, "good_table", "good_match"));
+  EXPECT_FALSE(pins::TableHasMatchField(ir_p4info, "bad_table", "good_match"));
+  EXPECT_FALSE(pins::TableHasMatchField(ir_p4info, "good_table", "bad_match"));
+}
+
+}  // namespace
+}  // namespace gpins