Add unit test that verifies fix for binary_check_expr::is_equal

Create two expressions with the same lhs/rhs but different ops, and
ensure that is_equal() returns false.

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

userspace/libsinsp/test/CMakeLists.txt

@@ -82,6 +82,7 @@ endif()
 file(GLOB_RECURSE TEST_HELPERS ${CMAKE_CURRENT_SOURCE_DIR}/helpers/*.cpp)
 
 set(LIBSINSP_UNIT_TESTS_SOURCES
+	ast_exprs.ut.cpp
 	test_utils.cpp
 	sinsp_with_test_input.cpp
 	cgroup_list_counter.ut.cpp

userspace/libsinsp/test/ast_exprs.ut.cpp

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: Apache-2.0
+/*
+Copyright (C) 2024 The Falco 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.
+
+*/
+
+#include <libsinsp/filter/parser.h>
+#include <gtest/gtest.h>
+
+using namespace libsinsp::filter::ast;
+
+static std::unique_ptr<expr> make_expr(const std::string& cond)
+{
+	libsinsp::filter::parser p(cond);
+
+	std::unique_ptr<expr> e = p.parse();
+
+	return e;
+}
+
+TEST(ast, compare_binary_check_exprs)
+{
+	std::unique_ptr<expr> e1 = make_expr("evt.num >= 0");
+	std::unique_ptr<expr> e2 = make_expr("evt.num = 0");
+	ASSERT_FALSE(e1->is_equal(e2.get()));
+}