chore(userspace/libsinsp): add small test around sinsp_observer.

Signed-off-by: Federico Di Pierro <nierro92@gmail.com>

Author: FedeDP

userspace/libsinsp/test/classes/sinsp_observer.cpp

@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: Apache-2.0
+/*
+Copyright (C) 2025 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 <sinsp_with_test_input.h>
+#include "sinsp_observer.h"
+
+class test_observer : public sinsp_observer {
+public:
+	test_observer(): clone_counter(0), execve_counter(0) {}
+
+	void on_read(sinsp_evt* evt,
+	             int64_t tid,
+	             int64_t fd,
+	             sinsp_fdinfo* fdinfo,
+	             const char* data,
+	             uint32_t original_len,
+	             uint32_t len) override {}
+
+	void on_write(sinsp_evt* evt,
+	              int64_t tid,
+	              int64_t fd,
+	              sinsp_fdinfo* fdinfo,
+	              const char* data,
+	              uint32_t original_len,
+	              uint32_t len) override {}
+
+	void on_sendfile(sinsp_evt* evt, int64_t fdin, uint32_t len) override {}
+	void on_connect(sinsp_evt* evt, uint8_t* packed_data) override {}
+
+	void on_accept(sinsp_evt* evt,
+	               int64_t newfd,
+	               uint8_t* packed_data,
+	               sinsp_fdinfo* new_fdinfo) override {}
+
+	void on_file_open(sinsp_evt* evt, const std::string& fullpath, uint32_t flags) override {}
+	void on_error(sinsp_evt* evt) override {}
+	void on_erase_fd(erase_fd_params* params) override {}
+	void on_socket_shutdown(sinsp_evt* evt) override {}
+	void on_execve(sinsp_evt* evt) override { execve_counter++; }
+
+	void on_clone(sinsp_evt* evt, sinsp_threadinfo* newtinfo, int64_t tid_collision) override {
+		clone_counter++;
+	}
+
+	void on_bind(sinsp_evt* evt) override {}
+
+	bool on_resolve_container(sinsp_container_manager* manager,
+	                          sinsp_threadinfo* tinfo,
+	                          bool query_os_for_missing_info) override {
+		return true;
+	}
+
+	void on_socket_status_changed(sinsp_evt* evt) override {}
+
+	int get_clone_counter() const { return clone_counter; }
+
+	int get_execve_counter() const { return execve_counter; };
+
+private:
+	int clone_counter;
+	int execve_counter;
+};
+
+TEST_F(sinsp_with_test_input, sinsp_observer) {
+	add_default_init_thread();
+	open_inspector();
+
+	test_observer observer;
+
+	m_inspector.set_observer(&observer);
+
+	/* clone exit event */
+	generate_clone_x_event(22, INIT_TID, INIT_PID, INIT_PTID);
+	ASSERT_EQ(observer.get_clone_counter(), 1);
+	ASSERT_EQ(observer.get_execve_counter(), 0);
+
+	/* execve exit event */
+	generate_execve_enter_and_exit_event(0, 11, 11, 11, 11);
+	ASSERT_EQ(observer.get_clone_counter(), 1);
+	ASSERT_EQ(observer.get_execve_counter(), 1);
+}